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Cross-account and cross-region deployment using GitHub actions and AWS CDK

Post Syndicated from DAMODAR SHENVI WAGLE original https://aws.amazon.com/blogs/devops/cross-account-and-cross-region-deployment-using-github-actions-and-aws-cdk/

GitHub Actions is a feature on GitHub’s popular development platform that helps you automate your software development workflows in the same place you store code and collaborate on pull requests and issues. You can write individual tasks called actions, and combine them to create a custom workflow. Workflows are custom automated processes that you can set up in your repository to build, test, package, release, or deploy any code project on GitHub.

A cross-account deployment strategy is a CI/CD pattern or model in AWS. In this pattern, you have a designated AWS account called tools, where all CI/CD pipelines reside. Deployment is carried out by these pipelines across other AWS accounts, which may correspond to dev, staging, or prod. For more information about a cross-account strategy in reference to CI/CD pipelines on AWS, see Building a Secure Cross-Account Continuous Delivery Pipeline.

In this post, we show you how to use GitHub Actions to deploy an AWS Lambda-based API to an AWS account and Region using the cross-account deployment strategy.

Using GitHub Actions may have associated costs in addition to the cost associated with the AWS resources you create. For more information, see About billing for GitHub Actions.

Prerequisites

Before proceeding any further, you need to identify and designate two AWS accounts required for the solution to work:

  • Tools – Where you create an AWS Identity and Access Management (IAM) user for GitHub Actions to use to carry out deployment.
  • Target – Where deployment occurs. You can call this as your dev/stage/prod environment.

You also need to create two AWS account profiles in ~/.aws/credentials for the tools and target accounts, if you don’t already have them. These profiles need to have sufficient permissions to run an AWS Cloud Development Kit (AWS CDK) stack. They should be your private profiles and only be used during the course of this use case. So, it should be fine if you want to use admin privileges. Don’t share the profile details, especially if it has admin privileges. I recommend removing the profile when you’re finished with this walkthrough. For more information about creating an AWS account profile, see Configuring the AWS CLI.

Solution overview

You start by building the necessary resources in the tools account (an IAM user with permissions to assume a specific IAM role from the target account to carry out deployment). For simplicity, we refer to this IAM role as the cross-account role, as specified in the architecture diagram.

You also create the cross-account role in the target account that trusts the IAM user in the tools account and provides the required permissions for AWS CDK to bootstrap and initiate creating an AWS CloudFormation deployment stack in the target account. GitHub Actions uses the tools account IAM user credentials to the assume the cross-account role to carry out deployment.

In addition, you create an AWS CloudFormation execution role in the target account, which AWS CloudFormation service assumes in the target account. This role has permissions to create your API resources, such as a Lambda function and Amazon API Gateway, in the target account. This role is passed to AWS CloudFormation service via AWS CDK.

You then configure your tools account IAM user credentials in your Git secrets and define the GitHub Actions workflow, which triggers upon pushing code to a specific branch of the repo. The workflow then assumes the cross-account role and initiates deployment.

The following diagram illustrates the solution architecture and shows AWS resources across the tools and target accounts.

Architecture diagram

Creating an IAM user

You start by creating an IAM user called git-action-deployment-user in the tools account. The user needs to have only programmatic access.

  1. Clone the GitHub repo aws-cross-account-cicd-git-actions-prereq and navigate to folder tools-account. Here you find the JSON parameter file src/cdk-stack-param.json, which contains the parameter CROSS_ACCOUNT_ROLE_ARN, which represents the ARN for the cross-account role we create in the next step in the target account. In the ARN, replace <target-account-id> with the actual account ID for your designated AWS target account.                                             Replace <target-account-id> with designated AWS account id
  2. Run deploy.sh by passing the name of the tools AWS account profile you created earlier. The script compiles the code, builds a package, and uses the AWS CDK CLI to bootstrap and deploy the stack. See the following code:
cd aws-cross-account-cicd-git-actions-prereq/tools-account/
./deploy.sh "<AWS-TOOLS-ACCOUNT-PROFILE-NAME>"

You should now see two stacks in the tools account: CDKToolkit and cf-GitActionDeploymentUserStack. AWS CDK creates the CDKToolkit stack when we bootstrap the AWS CDK app. This creates an Amazon Simple Storage Service (Amazon S3) bucket needed to hold deployment assets such as a CloudFormation template and Lambda code package. cf-GitActionDeploymentUserStack creates the IAM user with permission to assume git-action-cross-account-role (which you create in the next step). On the Outputs tab of the stack, you can find the user access key and the AWS Secrets Manager ARN that holds the user secret. To retrieve the secret, you need to go to Secrets Manager. Record the secret to use later.

Stack that creates IAM user with its secret stored in secrets manager

Creating a cross-account IAM role

In this step, you create two IAM roles in the target account: git-action-cross-account-role and git-action-cf-execution-role.

git-action-cross-account-role provides required deployment-specific permissions to the IAM user you created in the last step. The IAM user in the tools account can assume this role and perform the following tasks:

  • Upload deployment assets such as the CloudFormation template and Lambda code package to a designated S3 bucket via AWS CDK
  • Create a CloudFormation stack that deploys API Gateway and Lambda using AWS CDK

AWS CDK passes git-action-cf-execution-role to AWS CloudFormation to create, update, and delete the CloudFormation stack. It has permissions to create API Gateway and Lambda resources in the target account.

To deploy these two roles using AWS CDK, complete the following steps:

  1. In the already cloned repo from the previous step, navigate to the folder target-account. This folder contains the JSON parameter file cdk-stack-param.json, which contains the parameter TOOLS_ACCOUNT_USER_ARN, which represents the ARN for the IAM user you previously created in the tools account. In the ARN, replace <tools-account-id> with the actual account ID for your designated AWS tools account.                                             Replace <tools-account-id> with designated AWS account id
  2. Run deploy.sh by passing the name of the target AWS account profile you created earlier. The script compiles the code, builds the package, and uses the AWS CDK CLI to bootstrap and deploy the stack. See the following code:
cd ../target-account/
./deploy.sh "<AWS-TARGET-ACCOUNT-PROFILE-NAME>"

You should now see two stacks in your target account: CDKToolkit and cf-CrossAccountRolesStack. AWS CDK creates the CDKToolkit stack when we bootstrap the AWS CDK app. This creates an S3 bucket to hold deployment assets such as the CloudFormation template and Lambda code package. The cf-CrossAccountRolesStack creates the two IAM roles we discussed at the beginning of this step. The IAM role git-action-cross-account-role now has the IAM user added to its trust policy. On the Outputs tab of the stack, you can find these roles’ ARNs. Record these ARNs as you conclude this step.

Stack that creates IAM roles to carry out cross account deployment

Configuring secrets

One of the GitHub actions we use is aws-actions/[email protected]. This action configures AWS credentials and Region environment variables for use in the GitHub Actions workflow. The AWS CDK CLI detects the environment variables to determine the credentials and Region to use for deployment.

For our cross-account deployment use case, aws-actions/[email protected] takes three pieces of sensitive information besides the Region: AWS_ACCESS_KEY_ID, AWS_ACCESS_KEY_SECRET, and CROSS_ACCOUNT_ROLE_TO_ASSUME. Secrets are recommended for storing sensitive pieces of information in the GitHub repo. It keeps the information in an encrypted format. For more information about referencing secrets in the workflow, see Creating and storing encrypted secrets.

Before we continue, you need your own empty GitHub repo to complete this step. Use an existing repo if you have one, or create a new repo. You configure secrets in this repo. In the next section, you check in the code provided by the post to deploy a Lambda-based API CDK stack into this repo.

  1. On the GitHub console, navigate to your repo settings and choose the Secrets tab.
  2. Add a new secret with name as TOOLS_ACCOUNT_ACCESS_KEY_ID.
  3. Copy the access key ID from the output OutGitActionDeploymentUserAccessKey of the stack GitActionDeploymentUserStack in tools account.
  4. Enter the ID in the Value field.                                                                                                                                                                Create secret
  5. Repeat this step to add two more secrets:
    • TOOLS_ACCOUNT_SECRET_ACCESS_KEY (value retrieved from the AWS Secrets Manager in tools account)
    • CROSS_ACCOUNT_ROLE (value copied from the output OutCrossAccountRoleArn of the stack cf-CrossAccountRolesStack in target account)

You should now have three secrets as shown below.

All required git secrets

Deploying with GitHub Actions

As the final step, first clone your empty repo where you set up your secrets. Download and copy the code from the GitHub repo into your empty repo. The folder structure of your repo should mimic the folder structure of source repo. See the following screenshot.

Folder structure of the Lambda API code

We can take a detailed look at the code base. First and foremost, we use Typescript to deploy our Lambda API, so we need an AWS CDK app and AWS CDK stack. The app is defined in app.ts under the repo root folder location. The stack definition is located under the stack-specific folder src/git-action-demo-api-stack. The Lambda code is located under the Lambda-specific folder src/git-action-demo-api-stack/lambda/ git-action-demo-lambda.

We also have a deployment script deploy.sh, which compiles the app and Lambda code, packages the Lambda code into a .zip file, bootstraps the app by copying the assets to an S3 bucket, and deploys the stack. To deploy the stack, AWS CDK has to pass CFN_EXECUTION_ROLE to AWS CloudFormation; this role is configured in src/params/cdk-stack-param.json. Replace <target-account-id> with your own designated AWS target account ID.

Update cdk-stack-param.json in git-actions-cross-account-cicd repo with TARGET account id

Finally, we define the Git Actions workflow under the .github/workflows/ folder per the specifications defined by GitHub Actions. GitHub Actions automatically identifies the workflow in this location and triggers it if conditions match. Our workflow .yml file is named in the format cicd-workflow-<region>.yml, where <region> in the file name identifies the deployment Region in the target account. In our use case, we use us-east-1 and us-west-2, which is also defined as an environment variable in the workflow.

The GitHub Actions workflow has a standard hierarchy. The workflow is a collection of jobs, which are collections of one or more steps. Each job runs on a virtual machine called a runner, which can either be GitHub-hosted or self-hosted. We use the GitHub-hosted runner ubuntu-latest because it works well for our use case. For more information about GitHub-hosted runners, see Virtual environments for GitHub-hosted runners. For more information about the software preinstalled on GitHub-hosted runners, see Software installed on GitHub-hosted runners.

The workflow also has a trigger condition specified at the top. You can schedule the trigger based on the cron settings or trigger it upon code pushed to a specific branch in the repo. See the following code:

name: Lambda API CICD Workflow
# This workflow is triggered on pushes to the repository branch master.
on:
  push:
    branches:
      - master

# Initializes environment variables for the workflow
env:
  REGION: us-east-1 # Deployment Region

jobs:
  deploy:
    name: Build And Deploy
    # This job runs on Linux
    runs-on: ubuntu-latest
    steps:
      # Checkout code from git repo branch configured above, under folder $GITHUB_WORKSPACE.
      - name: Checkout
        uses: actions/[email protected]
      # Sets up AWS profile.
      - name: Configure AWS credentials
        uses: aws-actions/[email protected]
        with:
          aws-access-key-id: ${{ secrets.TOOLS_ACCOUNT_ACCESS_KEY_ID }}
          aws-secret-access-key: ${{ secrets.TOOLS_ACCOUNT_SECRET_ACCESS_KEY }}
          aws-region: ${{ env.REGION }}
          role-to-assume: ${{ secrets.CROSS_ACCOUNT_ROLE }}
          role-duration-seconds: 1200
          role-session-name: GitActionDeploymentSession
      # Installs CDK and other prerequisites
      - name: Prerequisite Installation
        run: |
          sudo npm install -g [email protected]
          cdk --version
          aws s3 ls
      # Build and Deploy CDK application
      - name: Build & Deploy
        run: |
          cd $GITHUB_WORKSPACE
          ls -a
          chmod 700 deploy.sh
          ./deploy.sh

For more information about triggering workflows, see Triggering a workflow with events.

We have configured a single job workflow for our use case that runs on ubuntu-latest and is triggered upon a code push to the master branch. When you create an empty repo, master branch becomes the default branch. The workflow has four steps:

  1. Check out the code from the repo, for which we use a standard Git action actions/[email protected]. The code is checked out into a folder defined by the variable $GITHUB_WORKSPACE, so it becomes the root location of our code.
  2. Configure AWS credentials using aws-actions/[email protected]. This action is configured as explained in the previous section.
  3. Install your prerequisites. In our use case, the only prerequisite we need is AWS CDK. Upon installing AWS CDK, we can do a quick test using the AWS Command Line Interface (AWS CLI) command aws s3 ls. If cross-account access was successfully established in the previous step of the workflow, this command should return a list of buckets in the target account.
  4. Navigate to root location of the code $GITHUB_WORKSPACE and run the deploy.sh script.

You can check in the code into the master branch of your repo. This should trigger the workflow, which you can monitor on the Actions tab of your repo. The commit message you provide is displayed for the respective run of the workflow.

Workflow for region us-east-1 Workflow for region us-west-2

You can choose the workflow link and monitor the log for each individual step of the workflow.

Git action workflow steps

In the target account, you should now see the CloudFormation stack cf-GitActionDemoApiStack in us-east-1 and us-west-2.

Lambda API stack in us-east-1 Lambda API stack in us-west-2

The API resource URL DocUploadRestApiResourceUrl is located on the Outputs tab of the stack. You can invoke your API by choosing this URL on the browser.

API Invocation Output

Clean up

To remove all the resources from the target and tools accounts, complete the following steps in their given order:

  1. Delete the CloudFormation stack cf-GitActionDemoApiStack from the target account. This step removes the Lambda and API Gateway resources and their associated IAM roles.
  2. Delete the CloudFormation stack cf-CrossAccountRolesStack from the target account. This removes the cross-account role and CloudFormation execution role you created.
  3. Go to the CDKToolkit stack in the target account and note the BucketName on the Output tab. Empty that bucket and then delete the stack.
  4. Delete the CloudFormation stack cf-GitActionDeploymentUserStack from tools account. This removes cross-account-deploy-user IAM user.
  5. Go to the CDKToolkit stack in the tools account and note the BucketName on the Output tab. Empty that bucket and then delete the stack.

Security considerations

Cross-account IAM roles are very powerful and need to be handled carefully. For this post, we strictly limited the cross-account IAM role to specific Amazon S3 and CloudFormation permissions. This makes sure that the cross-account role can only do those things. The actual creation of Lambda, API Gateway, and Amazon DynamoDB resources happens via the AWS CloudFormation IAM role, which AWS  CloudFormation assumes in the target AWS account.

Make sure that you use secrets to store your sensitive workflow configurations, as specified in the section Configuring secrets.

Conclusion

In this post we showed how you can leverage GitHub’s popular software development platform to securely deploy to AWS accounts and Regions using GitHub actions and AWS CDK.

Build your own GitHub Actions CI/CD workflow as shown in this post.

About the author

 

Damodar Shenvi Wagle is a Cloud Application Architect at AWS Professional Services. His areas of expertise include architecting serverless solutions, ci/cd and automation.

Recreate Q*bert’s cube-hopping action | Wireframe #42

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/recreate-qberts-cube-hopping-action-wireframe-42/

Code the mechanics of an eighties arcade hit in Python and Pygame Zero. Mark Vanstone shows you how

Players must change the colour of every cube to complete the level.

Late in 1982, a funny little orange character with a big nose landed in arcades. The titular Q*bert’s task was to jump around a network of cubes arranged in a pyramid formation, changing the colours of each as they went. Once the cubes were all the same colour, it was on to the next level; to make things more interesting, there were enemies like Coily the snake, and objects which helped Q*bert: some froze enemies in their tracks, while floating discs provided a lift back to the top of the stage.

Q*bert was designed by Warren Davis and Jeff Lee at the American company Gottlieb, and soon became such a smash hit that, the following year, it was already being ported to most of the home computer platforms available at the time. New versions and remakes continued to appear for years afterwards, with a mobile phone version appearing in 2003. Q*bert was by far Gottlieb’s most popular game, and after several changes in company ownership, the firm is now part of Sony’s catalogue – Q*bert’s main character even made its way into the 2015 film, Pixels.

Q*bert uses isometric-style graphics to draw a pseudo-3D display – something we can easily replicate in Pygame Zero by using a single cube graphic with which we make a pyramid of Actor objects. Starting with seven cubes on the bottom row, we can create a simple double loop to create the pile of cubes. Our Q*bert character will be another Actor object which we’ll position at the top of the pile to start. The game screen can then be displayed in the draw() function by looping through our 28 cube Actors and then drawing Q*bert.

Our homage to Q*bert. Try not to fall into the terrifying void.

We need to detect player input, and for this we use the built-in keyboard object and check the cursor keys in our update() function. We need to make Q*bert move from cube to cube so we can move the Actor 32 pixels on the x-axis and 48 pixels on the y-axis. If we do this in steps of 2 for x and 3 for y, we will have Q*bert on the next cube in 16 steps. We can also change his image to point in the right direction depending on the key pressed in our jump() function. If we use this linear movement in our move() function, we’ll see the Actor go in a straight line to the next block. To add a bit of bounce to Q*bert’s movement, we add or subtract (depending on the direction) the values in the bounce[] list. This will make a bit more of a curved movement to the animation.

Now that we have our long-nosed friend jumping around, we need to check where he’s landing. We can loop through the cube positions and check whether Q*bert is over each one. If he is, then we change the image of the cube to one with a yellow top. If we don’t detect a cube under Q*bert, then the critter’s jumped off the pyramid, and the game’s over. We can then do a quick loop through all the cube Actors, and if they’ve all been changed, then the player has completed the level. So those are the basic mechanics of jumping around on a pyramid of cubes. We just need some snakes and other baddies to annoy Q*bert – but we’ll leave those for you to add. Good luck!

Here’s Mark’s code for a Q*bert-style, cube-hopping platform game. To get it running on your system, you’ll need to install Pygame Zero. And to download the full code and assets, head here.

Get your copy of Wireframe issue 42

You can read more features like this one in Wireframe issue 42, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 42 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Recreate Q*bert’s cube-hopping action | Wireframe #42 appeared first on Raspberry Pi.

Recreate Time Pilot’s free-scrolling action | Wireframe #41

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/recreate-time-pilots-free-scrolling-action-wireframe-41/

Fly through the clouds in our re-creation of Konami’s classic 1980s shooter. Mark Vanstone has the code

Arguably one of Konami’s most successful titles, Time Pilot burst into arcades in 1982. Yoshiki Okamoto worked on it secretly, and it proved so successful that a sequel soon followed. In the original, the player flew through five eras, from 1910, 1940, 1970, 1982, and then to the far future: 2001. Aircraft start as biplanes and progress to become UFOs, naturally, by the last level.

Players also rescue other pilots by picking them up as they parachute from their aircraft. The player’s plane stays in the centre of the screen while other game objects move around it. The clouds that give the impression of movement have a parallax style to them, some moving faster than others, offering an illusion of depth.

To make our own version with Pygame Zero, we need eight frames of player aircraft images – one for each direction it can fly. After we create a player Actor object, we can get input from the cursor keys and change the direction the aircraft is pointing with a variable which will be set from zero to 7, zero being the up direction. Before we draw the player to the screen, we set the image of the Actor to the stem image name, plus whatever that direction variable is at the time. That will give us a rotating aircraft.

To provide a sense of movement, we add clouds. We can make a set of random clouds on the screen and move them in the opposite direction to the player aircraft. As we only have eight directions, we can use a lookup table to change the x and y coordinates rather than calculating movement values. When they go off the screen, we can make them reappear on the other side so that we end up with an ‘infinite’ playing area. Add a level variable to the clouds, and we can move them at different speeds on each update() call, producing the parallax effect. Then we need enemies. They will need the same eight frames to move in all directions. For this sample, we will just make one biplane, but more could be made and added.

Our Python homage to Konami’s arcade classic.

To get the enemy plane to fly towards the player, we need a little maths. We use the math.atan2() function to work out the angle between the enemy and the player. We convert that to a direction which we set in the enemy Actor object, and set its image and movement according to that direction variable. We should now have the enemy swooping around the player, but we will also need some bullets. When we create bullets, we need to put them in a list so that we can update each one individually in our update(). When the player hits the fire button, we just need to make a new bullet Actor and append it to the bullets list. We give it a direction (the same as the player Actor) and send it on its way, updating its position in the same way as we have done with the other game objects.

The last thing is to detect bullet hits. We do a quick point collision check and if there’s a match, we create an explosion Actor and respawn the enemy somewhere else. For this sample, we haven’t got any housekeeping code to remove old bullet Actors, which ought to be done if you don’t want the list to get really long, but that’s about all you need: you have yourself a Time Pilot clone!

Here’s Mark’s code for a Time Pilot-style free-scrolling shooter. To get it running on your system, you’ll need to install Pygame Zero. And to download the full code and assets, head here.

Get your copy of Wireframe issue 41

You can read more features like this one in Wireframe issue 41, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 41 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Recreate Time Pilot’s free-scrolling action | Wireframe #41 appeared first on Raspberry Pi.

How to enable X11 forwarding from Red Hat Enterprise Linux (RHEL), Amazon Linux, SUSE Linux, Ubuntu server to support GUI-based installations from Amazon EC2

Post Syndicated from Emma White original https://aws.amazon.com/blogs/compute/how-to-enable-x11-forwarding-from-red-hat-enterprise-linux-rhel-amazon-linux-suse-linux-ubuntu-server-to-support-gui-based-installations-from-amazon-ec2/

This post was written by Sivasamy Subramaniam, AWS Database Consultant.

In this post, I discuss enabling X11 forwarding from Red Hat Enterprise Linux (RHEL), Amazon Linux, SUSE Linux, Ubuntu servers running on Amazon EC2. This is helpful for system and database administrators, and application teams that want to perform software installations on Amazon EC2 using GUI method. This blog provides detailed steps around SSH and x11 tools, various network and operating system (OS) level settings, and best practices to achieve the X11 forwarding on Amazon EC2 when installing databases like Oracle using GUI.

There are several techniques to connect Amazon EC2 instances to manage OS level configurations. You typically use SSH clients (such as putty or SSH client) to establish the connection from the Windows or Mac-based laptop or bastion hosts or jump servers to connect with Amazon EC2 instances running OS. During the application installation or configuration, the application might require you to install software such as an Oracle database or a third-party database using GUI methods. This article talks about steps that must be done in order to forward the X11 screen to your highly secure Windows OS-based based bastion host.

 

Prerequisites

To complete this walkthrough the following is required:

 

  • Ensure that you have a bastion host running on Amazon EC2 with Windows OS. This OS must have access to the EC2 machines running Linux such as RHEL, Amazon Linux, SUSE Linux, and Ubuntu servers. If not, please configure a bastion host using Windows operating system with needed SSH access via port 22 to EC2 instance running Linux-based operating systems.
  • I recommend having Windows-based hosts in the same Availability Zone or Region as the EC2 Linux hosts that you plan to connect and forward X11 to. This is to avoid any high latency in X11 forwarding during your application installations.
  • Install tools such as putty and Xming in the Windows based bastion host that you want to SSH to Linux EC2 host and X11 forwarding.
  • Install Quartz if you want to redirect X11 to macOS. Quartz is package used in Mac for display management. To start using X11 forwarding to your Mac, use the -X switch. In other words, the SSH command looks like this “SSH -X -i “<ssh private key file name>” <user_name>@<ip-address>”. You must log out and log in back after installation of Quartz work properly.
  • In order to securely configure or install putty, refer to the section Configuring ssh-agent on Windows in the blog post Securely Connect to Linux Instances Running in a Private Amazon VPC.
  • I don’t recommend doing the X11 forwarding to the laptop because it’s not secure, and you must resolve latency issues if user is located in different Region than the EC2 instance hosted Region.
  • You may need sudo permission to run X11 forwarding commands as a root user in order to complete the setup.

 

Solution

Connect to your EC2 instance using SSH client, and perform following setup as needed.

Step 1: Verify or install required X11 packages.

To find out OS information and release, install required X11 packages and xclock or xterm. Installing xclock or xterm packages are optional as this is installed in this post to test the X11 forwarding.

  • List OS information and release with following command:

sudo cat /etc/os-release

  • List and install X11 packages with following command based on your operating system release and version:

Amazon Linux:

sudo yum list installed '*X11*'

sudo yum install xclock xterm

sudo yum install xorg-x11-xauth.x86_64 -y

sudo yum list installed '*X11*'

Red Hat Enterprise Linux:

sudo yum list installed '*X11*'

sudo yum install xterm

sudo yum install xorg-x11-xauth

sudo yum list installed '*X11*'

Note: The xorg-x11-apps package has been provided in the CodeReady Linux Builder Repository for RHEL8. So, I skipped installing this package, which has xclock and I used only xterm to test the X11 forwarding.

SUSE:

sudo zypper install xclock

sudo zypper install xauth

Ubuntu:

sudo apt list installed '*X11*'

sudo apt install x11-apps

sudo apt list installed '*X11*'

 

Step 2: Verify and configure X11 forwarding

  • On the Linux server, edit sshd_config file, set X11Forwarding parameter to yes, and restart the sshd service:

sudo  cat /etc/ssh/sshd_config |grep -i X11Forwarding

  • Enable “X11Forwarding yes” if this is set to “no”  and restart sshd service.

sudo  vi /etc/ssh/sshd_config

sudo  cat /etc/ssh/sshd_config |grep -i X11Forwarding

  • X11Forwarding yes

x110 forwarding yes and no

  • To Restart sshd:

sudo service sshd status

 

Step 3: Configure putty and Xming to perform X11 forwarding connect and verify X11 forwarding

Log in to your Windows bastion host. Then, open a fresh PuTTY session, and use a private key or password-based authentication per your organization setup. Then, test the xclock or xterm command to see x11 forwarding in action.

  • Click the xming utility you installed on Windows bastion host and have it running.

click on xming icon

  • Select Session from the Category pane on left. Set Host Name as your private IP, port 22 and Connection Type as SSH. Please note that you use the Private IP of EC2 instance later when you connect inside from the VPC/network.

putty config host ip

  • Go to Connection, and click Then, set Auto-login username as ec2-user, ubuntu, or whichever user you are allowed to logging in as.
  • Go to Connection, select SSH, and then click Then, click on Browse to select the private key generated earlier If you are using key based authentication.
  • Go to Connection, select SSH, and then click on Then, select enable X11 forwarding.
  • Set X display location as localhost:0.0

putty config with x11 forwarding

  • Go back to Session and click on Save after creating a session name in Saved session.

 Now that you set up PuTTY, xming and configuring the x11 settings, you can click on load button and then Open button. This opens up a new SSH terminal with x11 forwarding enabled. Now, I move on to the testing X11 forwarding.

  • Test the X11 from the use you logged in:

Example:

xauth list

export DISPLAY=localhost:10.0

xclock or xterm

X11 forwarding on Mac

  • It is simple to start using X11 forwarding to your Mac, use the -X switch.

Example:

“SSH -X -i "<ssh private key file name>" <user_name>@<ip-address>

xclock or xterm

 

You see that xclock or xterm window opened similar to the one following. This means your x11 forwarding setup working as expected, and you can start using GUI-based application installation or configuration by running the installer or configuration tools.

xclock to demonstrate this is correct

Step 4: Configure the EC2 Linux session to forward X11 if you are switching to different user after login to run GUI-based installation / commands

In this example: ec2-user is the user logged in with SSH and then switched to oracle user.

  • From the Logged User to identify the xauth details:

xauth list

env|grep DISPLAY

xauth list | grep unix`echo $DISPLAY | cut -c10-12` > /tmp/xauth

ll /tmp/xauth ; cat /tmp/xauth

  • Switch to the user where you want to run GUI-based installation or tools:

sudo su - oracle

xauth add `cat /tmp/xauth`

xauth list

env|grep DISPLAY

export DISPLAY=localhost:10.0

xclock

You see xclock or xterm window opened similar to the one following. This means your x11 forwarding setup working as expected even after switched to different user. You can start using GUI-based  application installation or configuration by running the installer or configuration tools.

another xclock to show the forwarding worked  

Conclusion

In this blog, I demonstrated how to configure Amazon EC2 instances running on various Linux-based operating systems to forward X11 to the Windows bastion host. This is helpful to any application installation that requires GUI-based installation methods. This is also helpful to any bastion hosts that provide highly secure and low latency environments to perform SSH related operations including GUI-based installations as this do not require any additional network configuration other than opening the port 22 for standard SSH authentication. Please try this walkthrough for yourself, and leave any comments following!

 

 

Code Jetpac’s rocket building action | Wireframe #40

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-jetpacs-rocket-building-action-wireframe-40/

Pick up parts of a spaceship, fuel it up, and take off in Mark Vanstone’s Python and Pygame Zero rendition of a ZX Spectrum classic

The original Jetpac, in all its 8-bit ZX Spectrum glory

For ZX Spectrum owners, there was something special about waiting for a game to load, with the sound of zeros and ones screeching from the cassette tape player next to the computer. When the loading screen – an image of an astronaut and Ultimate Play the Game’s logo – appeared, you knew the wait was going to be worthwhile. Created by brothers Chris and Tim Stamper in 1983, Jetpac was one of the first hits for their studio, Ultimate Play the Game. The game features the hapless astronaut Jetman, who must build and fuel a rocket from the parts dotted around the screen, all the while avoiding or shooting swarms of deadly aliens.

This month’s code snippet will provide the mechanics of collecting the ship parts and fuel to get Jetman’s spaceship to take off.  We can use the in-built Pygame Zero Actor objects for all the screen elements and the Actor collision routines to deal with gravity and picking up items. To start, we need to initialise our Actors. We’ll need our Jetman, the ground, some platforms, the three parts of the rocket, some fire for the rocket engines, and a fuel container. The way each Actor behaves will be determined by a set of lists. We have a list for objects with gravity, objects that are drawn each frame, a list of platforms, a list of collision objects, and the list of items that can be picked up.

Jetman jumps inside the rocket and is away. Hurrah!

Our draw() function is straightforward as it loops through the list of items in the draw list and then has a couple of conditional elements being drawn after. The update() function is where all the action happens: we check for keyboard input to move Jetman around, apply gravity to all the items on the gravity list, check for collisions with the platform list, pick up the next item if Jetman is touching it, apply any thrust to Jetman, and move any items that Jetman is holding to move with him. When that’s all done, we can check if refuelling levels have reached the point where Jetman can enter the rocket and blast off.

If you look at the helper functions checkCollisions() and checkTouching(), you’ll see that they use different methods of collision detection, the first being checking for a collision with a specified point so we can detect collisions with the top or bottom of an actor, and the touching collision is a rectangle or bounding box collision, so that if the bounding box of two Actors intersect, a collision is registered. The other helper function applyGravity() makes everything on the gravity list fall downward until the base of the Actor hits something on the collide list.

So that’s about it: assemble a rocket, fill it with fuel, and lift off. The only thing that needs adding is a load of pesky aliens and a way to zap them with a laser gun.

Here’s Mark’s Jetpac code. To get it running on your system, you’ll need to install Pygame Zero. And to download the full code and assets, head here.

Get your copy of Wireframe issue 40

You can read more features like this one in Wireframe issue 40, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 40 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

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AWS CodeArtifact and your package management flow – Best Practices for Integration

Post Syndicated from John Standish original https://aws.amazon.com/blogs/devops/integrating-aws-codeartifact-package-mgmt-flow/

You often use artifact repositories to store and share software or deployment packages. Centralized artifacts enable teams to operate independently and share versioned software artifacts across your organization. Sharing versioned artifacts across organizations increases code reuse and reduces delivery time. Having a central artifact store enables tighter artifact governance and improves security visibility. This post uses some of these patterns to show you how to integrate AWS CodeArtifact in an effective, cost-controlled, and efficient manner.

AWS CodeArtifact Diagram

AWS CodeArtifact Service Usage

AWS CodeArtifact concepts

AWS CodeArtifact uses the following elements:

  • Asset – An individual file stored in AWS CodeArtifact that is associated with a package version, such as an npm .tgz file or Maven POM and JAR files
  • Package – A package is a bundle of software and the metadata that is required to resolve dependencies and install the software. AWS CodeArtifact supports npmPyPI, and Maven package formats.
  • Repository – An CodeArtifact repository contains a set of package versions, each of which maps to a set of assets. Repositories are polyglot—a single repository can contain packages of any supported type. Each repository exposes endpoints for fetching and publishing packages using tools like the npm CLI, the Maven CLI (mvn), and pip.
  • Domain – Repositories are aggregated into a higher-level entity known as a domain. The domain allows organizational policy to be applied across multiple repositories. A domain deduplicates storage of the repositories packages.

Creating a domain based on organizational ownership

When you create a domain in CodeArtifact, it’s important to organize the domain by ownership within the organization. An example would be a a company being a domain, and the products being repositories. Domains allow you to apply organizational policies across multiple repositories. Generally we recommend creating one domain per company. In some cases it may also be beneficial to have a sandbox domain where prototype repositories reside. In a sandbox domain teams are at liberty to create their own repositories and experiment as needed, without affecting product deliverable assets. Using a sandbox domain will duplicate packages, isolate repositories since you can not copy packages between domains, and increase costs since package deduplication is handle at the domain level. Organizing packages by domain ownership increases the cache hits on a package within the domain and reduces cost for each subsequent package fetch request.

Whenever a package is fetched from a repository, the asset is cached in your CodeArtifact domain to minimize the cost of subsequent downstream requests. A given asset only needs to be stored once in a domain, even if it’s available in two—or two thousand—repositories. That means you only pay for storage once. Copying a package version with the CopyPackageVersions API is only possible between repositories within the same CodeArtifact domain.

You can create a domain for your organization by calling create-domain in the AWS Command Line Interface (AWS CLI), AWS SDK, or on the CodeArtifact console. See the following code:

aws codeartifact create-domain --domain "my-org"

After creating the domain you will see the domains listed in the Domains section on the CodeArtifact console.

AWS CodeArtifact domains per governing organization

Organizing packages by domain ownership

Using a shared repository

A shared repository is applicable when a team feels that a component is useful to the rest of the organization and isn’t in an experimental state, personal project, and not meant for wide distribution within the organization. Examples of shared components are open source public repositories (npm, PyPI, and Maven), authentication, logging, or helper libraries. Shared libraries aren’t related to product libraries; for instance, a service contract library shouldn’t live in a shared repository. The shared repository should be marked read-only to all users except for the publishing IAM role. At Amazon, we have found that many teams want to consume common packages as part of their application build, and don’t need to publish any package themselves. Those teams don’t need their own repository and pull packages from shared. Overall, approximately 80% of packages are downloaded from the shared repository, and 20% from team or project specific repositories.

You can create a shared repository by calling the create-repository command and setting a resource policy that makes the repository read-only.

Here is how you create a repository with the AWS CLI using the create-repository command. See the following code:

aws codeartifact create-repository --domain "my-org" \
--domain-owner "account-id" --repository "my-shared-repo-name" \
--description "My new repository"

Next you make the repository read-only by setting a resource policy. See the following code:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
		"codeartifact:DescribePackageVersion",
                "codeartifact:DescribeRepository",
                "codeartifact:GetPackageVersionReadme",
                "codeartifact:GetRepositoryEndpoint",
                "codeartifact:ListPackages",
                "codeartifact:ListPackageVersions",
                "codeartifact:ListPackageVersionAssets",
                "codeartifact:ListPackageVersionDependencies",
                "codeartifact:ReadFromRepository"
            ],
            "Effect": "Allow",
            "Principal": {
                "AWS": "arn:aws:iam::444455556666:root"
            },
            "Resource": "*"
        }
    ]
}

To attach a resource polcicy to a repository by calling the put-repository-permissions command. See the following code:

aws codeartifact put-repository-permissions-policy --domain "my-org" \
--domain-owner "account-id" --repository "my-shared-repo-name" \
--policy-document file:///PATH/TO/policy.json

When you have created the repository, you will see it listed in the Repositories section on the CodeArtifact console.

A list of shared repositories in AWS CodeArtifact

Shared repositories in AWS CodeArtifact

External repository connections

CodeArtifact enables you to set external repository connections and replicate them within CodeArtifact. An external connection reduces the downstream dependency on the remote external repository. When you request a package from the CodeArtifact repository that’s not already present in the repository, the package can be fetched from the external connection. This makes it possible to consume open-source dependencies used by your application. Using an external connection reduces interruption in your development process for package external dependencies, an example is if a package is removed from a public repository, you will still have a copy of the package stored in CodeArtifact. You should have a one-to-one mapping with external repositories, and rather than have multiple CodeArtifact repositories pointing to the same public repository. Each asset that CodeArtifact imports into your repository from a public repository is billed as a single request, and each connection must reconcile and fetch the package before the response is returned. By having a one-to-one mapping, you can increase cache hits, reduces time to download an application dependency from CodeArtifact, and reduce the number of external package resolution requests. Associating an external repository connection with your repository is done using the associate-external-connection command. See the following code:

aws codeartifact associate-external-connection \
--domain "my-org" --domain-owner "account-id" \
--repository "my-external-repo" --external-connection public:npmjs

Once you have associated an external connection with your repository, you’ll see the external connection visible in the Repositories section detail. In this example we’ve connected the repository to the external npmjs repository.

External connection to npmjs with AWS CodeArtifact repositories

External connection to npmjs for an AWS CodeArtifact repository

Team and product repositories

When working in distributed teams, you often align repositories to the product or service ownership. Teams working on there own repository can update as needed. An example would be creating a private package that your team only uses internally.

See the following code:

aws codeartifact create-repository --domain my-org \
--domain-owner account-id --repository my-team-repo \
--description "My new team repository"

As team’s develop against the package they will need to publish their changes to the repository. As part of your development pipeline you would publish the package to the repository. See the following code for an example:

# Log in to CodeArtifact
aws codeartifact login --tool npm \
--domain "my-org" --domain-owner "account-id" \
--repository "my-team-repo"

# Run build commands here
...

# Set $VERSION from your build system
npm version $VERSION

# Publish to CodeArtifact
npm publish

After testing the feature and you find that it will be usable across your organization, you can copy the package into your shared repository. See the following code:

# Promoting to a shared repo
aws codeartifact copy-package-versions --domain "my-org" \
--domain-owner "account-id" --source-repository "my-team-repo" \
--destination-repository "my-shared-repo" \
--package my-package --format npm \
--versions '["6.0.2"]'

Once you’ve created your shared repository you will see the repositories updated as shown here.

Team and product repositories in AWS CodeArtifact

Team and product repositories

Sharing repositories across accounts

Often teams or workloads have separate accounts within an organization. This is a recommended practice because it clearly defines operational boundaries and domain of ownership and establishes security boundaries. If your organization uses a multi-account strategy, you can share repositories across accounts using CodeArtifact resource policy. Teams can develop in their own account and publish to a CodeArtifact repository controlled in a shared account.

Here you see a list of repositories, which includes both a shared and team repository.

Cross account sharing of AWS CodeArtifact repositories

Cross account sharing of AWS CodeArtifact repositories

Using Amazon CloudWatch Events when a package is pushed

When a package is pushed into a repository, its change can affect software dependencies, teams, or process dependencies. When an artifact is pushed to CodeArtifact, an Amazon CloudWatch Events event is triggered, which you can trigger additional functionality. You can react to these events by subscribing to a CodeArtifact event in Amazon EventBridge. Some examples of reactions to a change you could take are: checking dependencies, deploying dependent services, notifying teams or services of a change, or building the dependencies.

You can also use EventBridge to start a pipeline in AWS CodePipeline, notify an Amazon Simple Notification Service (Amazon SNS) topic, and have that call AWS Chatbot. For more information see, CodeArtifact event format and example. If you are looking to integrate AWS Chatbot into your delivery flow, see Receive AWS Developer Tools Notifications over Slack using AWS Chatbot.

Deploying code in a hybrid environment

You can enable seamless software deployment into AWS and on-premises environments by integrating CodeArtifact with software build and deployment services. You can use CodeArtifact with your existing development pipeline tooling such as NPM, Python, and Maven. With native support for these package managers, you can access CodeArtifact wherever you operate today.

First, log in to CodeArtifact, build your code, and finally publish using npm publish with the following code:

# Log in to CodeArtifact 
aws codeartifact login --tool npm \
--domain "my-org" --domain-owner "account-id" \
--repository "my-team-repo"

# Run build commands here 
... 

# Set $VERSION from your build system 
npm version $VERSION 

# Publish to CodeArtifact 
npm publish

Cleaning Up

When you’re ready to clean up the repositories and domains you’ve created, you’ll need to remove them in a specific order. Please be aware that deleting a repository is a destructive action which will remove any stored packages. To delete a domain and delete a repository created from the previous sections in this blog, you will be using the delete-domain and delete-repository commands.

You will need to remove the domain and repository in the following order:

  1. Remove any repositories in a domain
  2. Remove the domain

To delete the repository and domain, see the following code:

# Delete the repository
aws codeartifact delete-repository --domain "my-org" --domain-owner "account-id" --repository "my-team-repo"

# Delete the domain
aws codeartifact delete-domain --domain "my-org" --domain-owner "account-id"

Conclusion

This post covered how to integrate CodeArtifact into your delivery flow and use CodeArtifact effectively. A shared repository approach aides in creating reusable components across your organization. Using team repositories and promoting to a consumable repository allows your teams to iterate independently. For more information, see Getting started with CodeArtifact.

About the Author

John Standish

John Standish is a Solutions Architect at AWS and spent over 13 years as a Microsoft .Net developer. Outside of work, he enjoys playing video games, cooking, and watching hockey.

Yogesh Chaturvedi

Yogesh Chaturvedi is a Solutions Architect at AWS and has over 20 years of software development and architecture experience.

 

Code Gauntlet’s four-player co-op mode | Wireframe #39

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-gauntlets-four-player-co-op-mode-wireframe-39/

Four players dungeon crawling at once? Mark Vanstone shows you how to recreate Gauntlet’s co-op mode in Python and Pygame Zero.

Players collected items while battling their way through dungeons. Shooting food was a definite faux pas.

Atari’s Gauntlet was an eye-catching game, not least because it allowed four people to explore its dungeons together. Each player could choose one of four characters, each with its own abilities – there was a warrior, a Valkyrie, a wizard, and an elf – and surviving each dungeon required slaughtering enemies and the constant gathering of food, potions, and keys that unlocked doors and exits.

Designed by Ed Logg, and loosely based on the tabletop RPG Dungeons & Dragons, as well as John Palevich’s 1983 dungeon crawler, Dandy, Gauntlet was a big success. It was ported to most of the popular home systems at the time, and Atari released a sequel arcade machine, Gauntlet II, in 1986.

Atari’s original arcade machine featured four joysticks, but our example will mix keyboard controls and gamepad inputs. Before we deal with the movement, we’ll need some characters and dungeon graphics. For this example, we can make our dungeon from a large bitmap image and use a collision map to prevent our characters from clipping through walls. We’ll also need graphics for the characters moving in eight different directions. Each direction has three frames of walking animation, which makes a total of 24 frames per character. We can use a Pygame Zero Actor object for each character and add a few extra properties to keep track of direction and the current animation frame. If we put the character Actors in a list, we can loop through the list to check for collisions, move the player, or draw them to the screen.

We now test input devices for movement controls using the built-in Pygame keyboard object to test if keys are pressed. For example, keyboard.left will return True if the left arrow key is being held down. We can use the arrow keys for one player and the WASD keys for the other keyboard player. If we register x and y movements separately, then if two keys are pressed – for example, up and left – we can read that as a diagonal movement. In this way, we can get all eight directions of movement from just four keys.

For joystick or gamepad movement, we need to import the joystick module from Pygame. This provides us with methods to count the number of joystick or gamepad devices that are attached to the computer, and then initialise them for input. When we check for input from these devices, we just need to get the x-axis value and the y- axis value and then make it into an integer. Joysticks and gamepads should return a number between -1 and 1 on each axis, so if we round that number, we will get the movement value we need.

We can work out the direction (and the image we need to use) of the character with a small lookup table of x and y values and translate that to a frame number cycling through those three frames of animation as the character walks. Then all we need to do before we move the character is check they aren’t going to collide with a wall or another character. And that’s it – we now have a four-player control system. As for adding enemy spawners, loot, and keys – well, that’s a subject for another time.

Here’s Mark’s code snippet. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code and assets, go here.

Get your copy of Wireframe issue 39

You can read more features like this one in Wireframe issue 39, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 39 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

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Code Robotron: 2084’s twin-stick action | Wireframe #38

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-robotron-2084s-twin-stick-action-wireframe-38/

News flash! Before we get into our Robotron: 2084 code, we have some important news to share about Wireframe: as of issue 39, the magazine will be going monthly.

The new 116-page issue will be packed with more in-depth features, more previews and reviews, and more of the guides to game development that make the magazine what it is. The change means we’ll be able to bring you new subscription offers, and generally make the magazine more sustainable in a challenging global climate.

As for existing subscribers, we’ll be emailing you all to let you know how your subscription is changing, and we’ll have some special free issues on offer as a thank you for your support.

The first monthly issue will be out on 4 June, and subsequent editions will be published on the first Thursday of every month after that. You’ll be able to order a copy online, or you’ll find it in selected supermarkets and newsagents if you’re out shopping for essentials.

We now return you to our usual programming…

Move in one direction and fire in another with this Python and Pygame re-creation of an arcade classic. Raspberry Pi’s own Mac Bowley has the code.

Robotron: 2084 is often listed on ‘best game of all time’ lists, and has been remade and re-released for numerous systems over the years.

Robotron: 2084

Released back in 1982, Robotron: 2084 popularised the concept of the twin-stick shooter. It gave players two joysticks which allowed them to move in one direction while also shooting at enemies in another. Here, I’ll show you how to recreate those controls using Python and Pygame. We don’t have access to any sticks, only a keyboard, so we’ll be using the arrow keys for movement and WASD to control the direction of fire.

The movement controls use a global variable, a few if statements, and two built-in Pygame functions: on_key_down and on_key_up. The on_key_down function is called when a key on the keyboard is pressed, so when the player presses the right arrow key, for example, I set the x direction of the player to be a positive 1. Instead of setting the movement to 1, instead, I’ll add 1 to the direction. The on_key_down function is called when a button’s released. A key being released means the player doesn’t want to travel in that direction anymore and so we should do the opposite of what we did earlier – we take away the 1 or -1 we applied in the on_key_up function.

We repeat this process for each arrow key. Moving the player in the update() function is the last part of my movement; I apply a move speed and then use a playArea rect to clamp the player’s position.

The arena background and tank sprites were created in Piskel. Separate sprites for the tank allow the turret to rotate separately from the tracks.

Turn and fire

Now for the aiming and rotating. When my player aims, I want them to set the direction the bullets will fire, which functions like the movement. The difference this time is that when a player hits an aiming key, I set the direction directly rather than adjusting the values. If my player aims up, and then releases that key, the shooting will stop. Our next challenge is changing this direction into a rotation for the turret.

Actors in Pygame can be rotated in degrees, so I have to find a way of turning a pair of x and y directions into a rotation. To do this, I use the math module’s atan2 function to find the arc tangent of two points. The function returns a result in radians, so it needs to be converted. (You’ll also notice I had to adjust mine by 90 degrees. If you want to avoid having to do this, create a sprite that faces right by default.)

To fire bullets, I’m using a flag called ‘shooting’ which, when set to True, causes my turret to turn and fire. My bullets are dictionaries; I could have used a class, but the only thing I need to keep track of is an actor and the bullet’s direction.

Here’s Mac’s code snippet, which creates a simple twin-stick shooting mechanic in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code and assets, go here.

You can look at the update function and see how I’ve implemented a fire rate for the turret as well. You can edit the update function to take a single parameter, dt, which stores the time since the last frame. By adding these up, you can trigger a bullet at precise intervals and then reset the timer.

This code is just a start – you could add enemies and maybe other player weapons to make a complete shooting experience.

Get your copy of Wireframe issue 38

You can read more features like this one in Wireframe issue 38, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 38 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code Robotron: 2084’s twin-stick action | Wireframe #38 appeared first on Raspberry Pi.

Code a homage to Lunar Lander | Wireframe #37

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-a-homage-to-lunar-lander-wireframe-37/

Shoot for the moon in our Python version of the Atari hit, Lunar Lander. Mark Vanstone has the code.

Atari’s cabinet featured a thrust control, two buttons for rotating, and an abort button in case it all went horribly wrong.

Lunar Lander

First released in 1979 by Atari, Lunar Lander was based on a concept created a decade earlier. The original 1969 game (actually called Lunar) was a text-based affair that involved controlling a landing module’s thrust to guide it safely down to the lunar surface; a later iteration, Moonlander, created a more visual iteration of the same idea on the DEC VT50 graphics terminal.

Given that it appeared at the height of the late-seventies arcade boom, though, it was Atari’s coin-op that became the most recognisable version of Lunar Lander, arriving just after the tenth anniversary of the Apollo 11 moon landing. Again, the aim of the game was to use rotation and thrust controls to guide your craft, and gently set it down on a suitably flat platform. The game required efficient control of the lander, and extra points were awarded for parking successfully on more challenging areas of the landscape.

The arcade cabinet was originally going to feature a normal joystick, but this was changed to a double stalked up-down lever providing variable levels of thrust. The player had to land the craft against the clock with a finite amount of fuel with the Altitude, Horizontal Speed, and Vertical Speed readouts at the top of the screen as a guide. Four levels of difficulty were built into the game, with adjustments to landing controls and landing areas.

Our homage to the classic Lunar Lander. Can you land without causing millions of dollars’ worth of damage?

Making the game

To write a game like Lunar Lander with Pygame Zero, we can replace the vector graphics with a nice pre-drawn static background and use that as a collision detection mechanism and altitude meter. If our background is just black where the Lander can fly and a different colour anywhere the landscape is, then we can test pixels using the Pygame function image.get_at() to see if the lander has landed. We can also test a line of pixels from the Lander down the Y-axis until we hit the landscape, which will give us the lander’s altitude.

The rotation controls of the lander are quite simple, as we can capture the left and right arrow keys and increase or decrease the rotation of the lander; however, when thrust is applied (by pressing the up arrow) things get a little more complicated. We need to remember which direction the thrust came from so that the craft will continue to move in that direction even if it is rotated, so we have a direction property attached to our lander object. A little gravity is applied to the position of the lander, and then we just need a little bit of trigonometry to work out the movement of the lander based on its speed and direction of travel.

To judge if the lander has been landed safely or rammed into the lunar surface, we look at the downward speed and angle of the craft as it reaches an altitude of 1. If the speed is sufficiently slow and the angle is near vertical, then we trigger the landed message, and the game ends. If the lander reaches zero altitude without these conditions met, then we register a crash. Other elements that can be added to this sample are things like a limited fuel gauge and variable difficulty levels. You might even try adding the sounds of the rocket booster noise featured on the original arcade game.

Engage

The direction of thrust could be done in several ways. In this case, we’ve kept it simple, with one directional value which gradually moves in a new direction when an alternative thrust is applied. You may want to try making an X- and Y-axis direction calculation for thrust so that values are a combination of the two dimensions. You could also add joystick control to provide variable thrust input.

Here’s Mark’s code snippet, which creates a simple shooting game in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code and assets, go here.

Get your copy of Wireframe issue 36

You can read more features like this one in Wireframe issue 37, available directly from Raspberry Pi Press — we deliver worldwide.

And if you’d like a handy digital version of the magazine, you can also download issue 37 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a homage to Lunar Lander | Wireframe #37 appeared first on Raspberry Pi.

Make a Side Pocket-esque pool game | Wireframe #36

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/make-a-side-pocket-esque-pool-game-wireframe-36/

Recreate the arcade pool action of Data East’s Side Pocket. Raspberry Pi’s own Mac Bowley has the code.

In the original Side Pocket, the dotted line helped the player line up shots, while additional functions on the UI showed where and how hard you were striking the cue ball.

Created by Data East in 1986, Side Pocket was an arcade pool game that challenged players to sink all the balls on the table and achieve a minimum score to progress. As the levels went on, players faced more balls in increasingly difficult locations on the table.

Here, I’ll focus on three key aspects from Side Pocket: aiming a shot, moving the balls, and handling collisions for balls and pockets. This project is great for anyone who wants to dip their toe into 2D game physics. I’m going to use the Pygame’s built-in collision system as much as possible, to keep the code readable and short wherever I can.

Making a pool game

Before thinking about aiming and moving balls, I need a table to play on. I created both a border and a play area sprite using piskelapp.com; originally, this was one sprite, and I used a rect to represent the play area (see Figure 1). Changing to two sprites and making the play area an actor made all the collisions easier to handle and made everything much easier to place.

Figure 1: Our table with separate border. You could add some detail to your own table, or even adapt a photograph to make it look even more realistic.

For the balls, I made simple 32×32 sprites in varying colours. I need to be able to keep track of some information about each ball on the table, such as its position, a sprite, movement, and whether it’s been pocketed or not – once a ball’s pocketed, it’s removed from play. Each ball will have similar functionality as well – moving and colliding with each other. The best way to do this is with a class: a blueprint for each ball that I will make copies of when I need a new ball on the table.

class Ball:
def __init__(self, image, pos):
self.actor = Actor(image, center=pos, anchor=(“center”, “center”))
self.movement = [0, 0]
self.pocketed = False

def move(self):
self.actor.x += self.movement[0]
self.actor.y += self.movement[1]
if self.pocketed == False:
if self.actor.y < playArea.top + 16 or self.actor.y > playArea.bottom-16:
self.movement[1] = -self.movement[1]
self.actor.y = clamp(self.actor.y, playArea.top+16, playArea.bottom-16)
if self.actor.x < playArea.left+16 or self.actor.x > playArea.right-16:
self.movement[0] = -self.movement[0]
self.actor.x = clamp(self.actor.x, playArea.left+16, playArea.right-16)
else:
self.actor.x += self.movement[0]
self.actor.y += self.movement[1]
self.resistance()

def resistance(self):
# Slow the ball down
self.movement[0] *= 0.95
self.movement[1] *= 0.95

if abs(self.movement[0]) + abs(self.movement[1]) < 0.4:
self.movement = [0, 0]

The best part about using a class is that I only need to make one piece of code to move a ball, and I can reuse it for every ball on the table. I’m using an array to keep track of the ball’s movement – how much it will move each frame. I also need to make sure it bounces off the sides of the play area if it hits them. I’ll use an array to hold all the balls on the table.

To start with, I need a cue ball:

balls = []
cue_ball = Ball(“cue_ball.png”, (WIDTH//2, HEIGHT//2))
balls.append(cue_ball)

Aiming the shot

In Side Pocket, players control a dotted line that shows where the cue ball will go when they take a shot. Using the joystick or arrow buttons rotated the shot and moved the line, so players could aim to get the balls in the pockets (see Figure 2). To achieve this, we have to dive into our first bit of maths, converting a rotation in degrees to a pair of x and y movements. I decided my rotation would be at 0 degrees when pointing straight up; the player can then press the right and left arrow to increase or decrease this value.

Figure 2: The dotted line shows the trajectory of the ball. Pressing the left or right arrows rotates the aim.

Pygame Zero has some built-in attributes for checking the keyboard, which I’m taking full advantage of.

shot_rotation = 270.0 # Start pointing up table
turn_speed = 1
line = [] # To hold the points on my line
line_gap = 1/12
max_line_length = 400
def update():
global shot_rotation

## Rotate your aim
if keyboard[keys.LEFT]:
shot_rotation -= 1 * turn_speed
if keyboard[keys.RIGHT]:
shot_rotation += 1 * turn_speed

# Make the rotation wrap around
if shot_rotation > 360:
shot_rotation -= 360
if shot_rotation < 0:
shot_rotation += 360

At 0 degrees, my cue ball’s movement should be 0 in the x direction and -1 in y. When the rotation is 90 degrees, my x movement would be 1 and y would be zero; anything in between should be a fraction between the two numbers. I could use a lot of ‘if-elses’ to set this, but an easier way is to use sin and cos on my angle – I sin the rotation to get my x value and cos the rotation to get the y movement.

# The in-built functions need radian
rot_radians = shot_rotation * (math.pi/180)

x = math.sin(rot_rads)
y = -math.cos(rot_rads)
if not shot:
current_x = cue_ball.actor.x
current_y = cue_ball.actor.y
length = 0
line = []
while length < max_line_length:
hit = False
if current_y < playArea.top or current_y > playArea.bottom:
y = -y
hit = True
if current_x < playArea.left or current_x > playArea.right:
x = -x
hit = True
if hit == True:
line.append((current_x-(x*line_gap), current_y-(y*line_gap)))
length += math.sqrt(((x*line_gap)**2)+((y*line_gap)**2) )
current_x += x*line_gap
current_y += y*line_gap
line.append((current_x-(x*line_gap), current_y-(y*line_gap)))

I can then use those x and y co-ordinates to create a series of points for my aiming line.

Shooting the ball

To keep things simple, I’m only going to have a single shot speed – you could improve this design by allowing players to load up a more powerful shot over time, but I won’t do that here.

shot = False
ball_speed = 30


## Inside update
## Shoot the ball with the space bar
if keyboard[keys.SPACE] and not shot:
shot = True
cue_ball.momentum = [x*ball_speed, y*ball_speed]

When the shot variable is True, I’m going to move all the balls on my table – at the beginning, this is just the cue ball – but this code will also move the other balls as well when I add them.

# Shoot the ball and move all the balls on the table
else:
shot = False
balls_pocketed = []
collisions = []
for b in range(len(balls)):
# Move each ball
balls[b].move()
if abs(balls[b].momentum[0]) + abs(balls[b].momentum[1]) > 0:
shot = True

Each time I move the balls, I check whether they still have some movement left. I made a resistance function inside the ball class that will slow them down.

Collisions

Now for the final problem: getting the balls to collide with each other and the pockets. I need to add more balls and some pocket actors to my game in order to test the collisions.

balls.append(Ball(“ball_1.png”, (WIDTH//2 - 75, HEIGHT//2)))
balls.append(Ball(“ball_2.png”, (WIDTH//2 - 150, HEIGHT//2)))

pockets = []
pockets.append(Actor(“pocket.png”, topleft=(playArea.left, playArea.top), anchor=(“left”, “top”)))
# I create one of these actors for each pocket, they are not drawn

Each ball needs to be able to collide with the others, and when that happens, the direction and speed of the balls will change. Each ball will be responsible for changing the direction of the ball it has collided with, and I add a new function to my ball class:

def collide(self, ball):
collision_normal = [ball.actor.x - self.actor.x, ball.actor.y - self.actor.y]
ball_speed = math.sqrt(collision_normal[0]**2 + collision_normal[1]**2)
self_speed = math.sqrt(self.momentum[0]**2 + self.momentum[1]**2)
if self.momentum[0] == 0 and self.momentum[1] == 0:
ball.momentum[0] = -ball.momentum[0]
ball.momentum[1] = -ball.momentum[1]
elif ball_speed > 0:
collision_normal[0] *= 1/ball_speed
collision_normal[1] *= 1/ball_speed
ball.momentum[0] = collision_normal[0] * self_speed
ball.momentum[1] = collision_normal[1] * self_speed

When a collision happens, the other ball should move in the opposite direction to the collision. This is what allows you to line-up slices and knock balls diagonally into the pockets. Unlike the collisions with the edges, I can’t just reverse the x and y movement. I need to change its direction, and then give it a part of the current ball’s speed. Above, I’m using a normal to find the direction of the collision. You can think of this as the direction to the other ball as they collide.

Our finished pool game. See if you can expand it with extra balls and maybe a scoring system.

Handling collisions

I need to add to my update loop to detect and store the collisions to be handled after each set of movement.

# Check for collisions
for other in balls:
if other != b and b.actor.colliderect(other.actor):
collisions.append((b, other))
# Did it sink in the hole?
in_pocket = b.actor.collidelistall(pockets)
if len(in_pocket) > 0 and b.pocketed == False:
if b != cue_ball:
b.movement[0] = (pockets[in_pocket[0]].x - b.actor.x) / 20
b.movement[1] = (pockets[in_pocket[0]].y - b.actor.y) / 20
b.pocket = pockets[in_pocket[0]]
balls_pocketed.append(b)
else:
b.x = WIDTH//2
b.y = HEIGHT//2

First, I use the colliderect() function to check if any of the balls collide this frame – if they do, I add them to a list. This is so I handle all the movement first and then the collisions. Otherwise, I’m changing the momentum of balls that haven’t moved yet. I detect whether a pocket was hit as well; if so, I change the momentum so that the ball heads towards the pocket and doesn’t bounce off the walls anymore.

When all my balls have been moved, I can handle the collisions with both the other balls and the pockets:

for col in collisions:
col[0].collide(col[1])
if shot == False:
for b in balls_pocketed:
balls.remove(b)

And there you have it: the beginnings of an arcade pool game in the Side Pocket tradition. You can get the full code and assets right here.

Get your copy of Wireframe issue 36

You can read more features like this one in Wireframe issue 36, available directly from Raspberry Pi Press — we deliver worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 36 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Make a Side Pocket-esque pool game | Wireframe #36 appeared first on Raspberry Pi.

Code Hyper Sports’ shooting minigame | Wireframe #35

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-hyper-sports-shooting-minigame-wireframe-35/

Gun down the clay pigeons in our re-creation of a classic minigame from Konami’s Hyper Sports. Take it away, Mark Vanstone

Hyper Sports

Hyper Sports’ Japanese release was tied in with the 1984 Summer Olympics.

Hyper Sports

Konami’s sequel to its 1983 arcade hit, Track & Field, Hyper Sports offered seven games – or events – in which up to four players could participate. Skeet shooting was perhaps the most memorable game in the collection, and required just two buttons: fire left and fire right.

The display showed two target sights, and each moved up and down to come into line with the next clay disc’s trajectory. When the disc was inside the red target square, the player pressed the fire button, and if their timing was correct, the clay disc exploded. Points were awarded for being on target, and every now and then, a parrot flew across the screen, which could be gunned down for a bonus.

Making our game

To make a skeet shooting game with Pygame Zero, we need a few graphical elements. First, a static background of hills and grass, with two clay disc throwers each side of the screen, and a semicircle where our shooter stands – this can be displayed first, every time our draw() function is called.

We can then draw our shooter (created as an Actor) in the centre near the bottom of the screen. The shooter has three images: one central while no keys are pressed, and two for the directions left and right when the player presses the left or right keys. We also need to have two square target sights to the left and right above the shooter, which we can create as Actors.

When the clay targets appear, the player uses the left and right buttons to shoot either the left or right target respectively.

To make the clay targets, we create an array to hold disc Actor objects. In our update() function we can trigger the creation of a new disc based on a random number, and once created, start an animation to move it across the screen in front of the shooter. We can add a shadow to the discs by tracking a path diagonally across the screen so that the shadow appears at the correct Y coordinate regardless of the disc’s height – this is a simple way of giving our game the illusion of depth. While we’re in the update() function, looping around our disc object list, we can calculate the distance of the disc to the nearest target sight frame, and from that, work out which is the closest.

When we’ve calculated which disc is closest to the right-hand sight, we want to move the sight towards the disc so that their paths intersect. All we need to do is take the difference of the Y coordinates, divide by two, and apply that offset to the target sight. We also do the same for the left-hand sight. If the correct key (left or right arrows) is pressed at the moment a disc crosses the path of the sight frame, we register a hit and cycle the disc through a sequence of exploding frames. We can keep a score and display this with an overlay graphic so that the player knows how well they’ve done.

And that’s it! You may want to add multiple players and perhaps a parrot bonus, but we’ll leave that up to you.

Here’s Mark’s code snippet, which creates a simple shooting game in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code and assets, go here.

Get your copy of Wireframe issue 35

You can read more features like this one in Wireframe issue 35, available now at Tesco, WHSmith, and all good independent UK newsagents.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 35 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

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Recreate Flappy Bird’s flight mechanic | Wireframe #29

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/recreate-flappy-birds-flight-mechanic-wireframe-29/

From last year’s issue 29 of Wireframe magazine: learn how to create your own version of the simple yet addictive side-scroller Flappy Bird. Raspberry Pi’s Rik Cross shows you how.

Flappy Bird: ridiculously big in 2014, at least for a while.

Flappy Bird was released by programmer Dong Nguyen in 2013, and made use of a straightforward game mechanic to create an addictive hit. Tapping the screen provided ‘lift’ to the main character, which is used strategically to navigate through a series of moving pipes. A point is scored for each pipe successfully passed. The idea proved so addictive that Nguyen eventually regretted his creation and removed it from the Google and Apple app stores. In this article, I’ll show you how to recreate this simple yet time-consuming game, using Python and Pygame Zero.

The player’s motion is very similar to that employed in a standard platformer: falling down towards the bottom of the screen under gravity. See the article, Super Mario-style jumping physics in Wireframe #7 for more on creating this type of movement. Pressing a button (in our case, the SPACE bar) gives the player some upward thrust by setting its velocity to a negative value (i.e. upwards) larger than the value of gravity acting downwards. I’ve adapted and used two different images for the sprite (made by Imaginary Perception and available on opengameart.org), so that it looks like it’s flapping its wings to generate lift and move upwards.

Pressing the SPACE bar gives the bird ‘lift’ against gravity, allowing it to navigate through moving pipes.

Sets of pipes are set equally spaced apart horizontally, and move towards the player slowly each frame of the game. These pipes are stored as two lists of rectangles, top_pipes and bottom_pipes, so that the player can attempt to fly through gaps between the top and bottom pipes. Once a pipe in the top_pipes list reaches the left side of the screen past the player’s position, a score is incremented and the top and corresponding bottom pipes are removed from their respective lists. A new set of pipes is created at the right edge of the screen, creating a continuous challenge for the player. The y-position of the gap between each newly created pair of pipes is decided randomly (between minimum and maximum limits), which is used to calculate the position and height of the new pipes.

The game stops and a ‘Game over’ message appears if the player collides with either a pipe or the ground. The collision detection in the game uses the player.colliderect() method, which checks whether two rectangles overlap. As the player sprite isn’t exactly rectangular, it means that the collision detection isn’t pixel-perfect, and improvements could be made by using a different approach. Changing the values for GRAVITY, PIPE_GAP, PIPE_SPEED, and player.flap_velocity through a process of trial and error will result in a game that has just the right amount of frustration! You could even change these values as the player’s score increases, to add another layer of challenge.

Here’s Rik’s code, which gets an homage to Flappy Bird running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

If you’d like to read older issues of Wireframe magazine, you can find the complete back catalogue as free PDF downloads.

The latest issue of Wireframe is available in print to buy online from the Raspberry Pi Press store, with older physical issues heavily discounted too. You can also find Wireframe at local newsagents, but we should all be staying home as much as possible right now, so why not get your copy online and save yourself the trip?

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. And subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

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Code a homage to Marble Madness | Wireframe #34

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-a-homage-to-marble-madness-wireframe-34/

Code the map and movement basics of the innovative marble-rolling arcade game. Mark Vanstone shows you how.

The original Marble Madness

Each of Marble Madness’ six levels got progressively harder to navigate and had to be completed within a time limit.

Marble Madness

Hitting arcades in 1984, Atari’s Marble Madness presented a rather different control mechanism than other games of the time. The original arcade cabinet provided players with a trackball controller rather than a conventional joystick, and the aim was to guide a marble through a three-dimensional course in the fastest possible time. This meant that a player could change the angle and speed of the marble as it rolled and avoid various obstacles and baddies.

During development, designer Mark Cerny had to shelve numerous ideas for Marble Madness, since the hardware just wasn’t able to achieve the level of detail and interaction he wanted. The groundbreaking 3D display was one idea that made it through to the finished game: its pre-rendered, ray-traced isometric levels.

Marble Madness was the first game to use Atari’s System 1 upgradeable hardware platform, and also boasted the first use of an FM sound chip produced by Yamaha to create its distinctive stereo music. The game was popular in arcades to start with, but interest appeared to drop off after a few months – something Cerny attributed to the fact that the game didn’t take long to play. Marble Madness’s popularity endured in the home market, though, with ports made for most computers and consoles of the time – although inevitably, most of these didn’t support the original’s trackball controls.

Our Python version of Marble Madness

In our sample level, you can control the movement of the marble using the left and right arrow keys.

Making our game

For our version of Marble Madness, we’re going to use a combination of a rendered background and a heightmap in Pygame Zero, and write some simple physics code to simulate the marble rolling over the terrain’s flats and slopes. We can produce the background graphic using a 3D modelling program such as Blender. The camera needs to be set to Orthographic to get the forced perspective look we’re after. The angle of the camera is also important, in that we need an X rotation of 54.7 degrees and a Y rotation of 45 degrees to get the lines of the terrain correct. The heightmap can be derived from an overhead view of the terrain, but you’ll probably want to draw the heights of the blocks in a drawing package such as GIMP to give you precise colour values on the map.

The ball rolling physics are calculated from the grey-shaded heightmap graphic. We’ve left a debug mode in the code; by changing the debug variable to True, you can see how the marble moves over the terrain from the overhead viewpoint of the heightmap. The player can move the marble left and right with the arrow keys – on a level surface it will gradually slow down if no keys are pressed. If the marble is on a gradient on the heightmap, it will increase speed in the direction of the gradient. If the marble hits a section of black on the heightmap, it falls out of play, and we stop the game.

That takes care of the movement of the marble in two dimensions, but now we have to translate this to the rendered background’s terrain. The way we do this is to translate the Y coordinate of the marble as if the landscape was all at the same level – we multiply it by 0.6 – and then move it down the screen according to the heightmap data, which in this case moves the marble down 1.25 pixels for each shade of colour. We can use an overlay for items the marble always rolls behind, such as the finish flag. And with that, we have the basics of a Marble Madness level.

The code you'll need to make Marble Madness

Here’s Mark’s code snippet, which creates a Marble Madness level in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code, go here.

Module Madness

We use the image module from Pygame to sample the colour of the pixel directly under the marble on the heightmap. We also take samples from the left diagonal and the right diagonal to see if there is a change of height. We are only checking for left and right movement, but this sample could be expanded to deal with the two other directions and moving up the gradients, too. Other obstacles and enemies can be added using the same heightmap translations used for the marble, and other overlay objects can be added to the overlay graphic.

Get your copy of Wireframe issue 34

You can read more features like this one in Wireframe issue 34, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 34 for free in PDF format.

Wireframe #34

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a homage to Marble Madness | Wireframe #34 appeared first on Raspberry Pi.

Code a Zaxxon-style axonometric level | Wireframe #33

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-a-zaxxon-style-axonometric-level-wireframe-33/

Fly through the space fortress in this 3D retro forced scrolling arcade sample. Mark Vanstone has the details

A shot from Sega's arcade hit, Zaxxon

Zaxxon was the first arcade game to use an axonometric viewpoint, which made it look very different from its 2D rivals.

Zaxxon

When Zaxxon was first released by Sega in 1982, it was hailed as a breakthrough thanks to its pseudo-3D graphics. This axonometric projection ensured that Zaxxon looked unlike any other shooter around in arcades.

Graphics aside, Zaxxon offered a subtly different twist on other shooting games of the time, like Defender and Scramble; the player flew over either open space or a huge fortress, where they had to avoid obstacles of varying heights. Players could tell how high they were flying with the aid of an altimeter, and also the shadow beneath their ship (shadows were another of Zaxxon’s innovations). The aim of the game was to get to the end of each level without running out of fuel or getting shot down; if the player did this, they’d encounter an area boss called Zaxxon. Points were awarded for destroying gun turrets and fuel silos, and extra lives could be gained as the player progressed through the levels.

A shot of our Pygame version of Zaxxon

Our Zaxxon homage running in Pygame Zero: fly the spaceship through the fortress walls and obstacles with your cursor keys.

Making our level

For this code sample, we can borrow some of the techniques used in a previous Source Code article about Ant Attack (see Wireframe issue 15) since it also used an isometric display. Although the way the map display is built up is very similar, we’ll use a JSON file to store the map data. If you’ve not come across JSON before, it’s well worth learning about, as a number of web and mobile apps use it, and it can be read by Python very easily. All we need to do is load the JSON file, and Python automatically puts the data into a Python dictionary object for us to use.

In the sample, there’s a short run of map data 40 squares long with blocks for the floor, some low walls, higher walls, and a handful of fuel silos. To add more block types, just add data to the blocktypes area of the JSON file. The codes used in the map data are the index numbers of the blocktypes, so the first blocktypes is index 0, the next index 1, and so on. Our drawMap() function takes care of rendering the data into visual form and blits blocks from the top right to the bottom left of the screen. When the draw loop gets to where the ship is, it draws first the shadow and then the ship a little higher up the screen, depending on the altitude of the ship. The equation to translate the ship’s screen coordinates to a block position on the map is a bit simplistic, but in this case, it does the job well enough.

Cursor keys guide the movement of the spaceship, which is limited by the width of the map and a height of 85 pixels. There’s some extra code to display the ship if it isn’t on the map – for example, at the start, before it reaches the map area. To make the code snippet into a true Zaxxon clone, you’ll have to add some laser fire and explosions, a fuel gauge, and a scoring system, but this code sample should provide the basis you’ll need to get started.

Code for our Zaxxon homage

Here’s Mark’s code snippet, which creates a side-scrolling beat-’em-up in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code, go here.

Get your copy of Wireframe issue 33

You can read more features like this one in Wireframe issue 33, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 33 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a Zaxxon-style axonometric level | Wireframe #33 appeared first on Raspberry Pi.

Code a Kung-Fu Master style beat-’em-up | Wireframe #32

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-a-kung-fu-master-style-beat-em-up-wireframe-32/

Punch and kick your way through a rabble of bad dudes in a simple scrolling beat-’em-up. Mark Vanstone shows you how

Although released to tie in with Jackie Chan’s Spartan X, Kung-Fu Master was originally inspired by the Bruce Lee film, Game of Death.

Kung-Fu Master

Kung-Fu Master hit arcades in 1984. Its side-scrolling action, punching and kicking through an army of knife-throwing goons, helped create the beat-’em-up genre. In fact, its designer, Takashi Nishiyama, would go on to kickstart the Street Fighter series at Capcom, and later start up the Fatal Fury franchise at SNK.

In true eighties arcade style, Kung-Fu Master distils the elements of a chop-socky action film to its essentials. Hero Thomas and his girlfriend are attacked, she’s kidnapped, and Thomas fights his way through successive levels of bad guys to rescue her. The screen scrolls from side to side, and Thomas must use his kicks and punches to get from one side of the level to the other and climb the stairs to the next floor of the building.

Our Kung-Fu Master homage features punches, kicks, and a host of goons to use them on.

Making our brawler

To recreate this classic with Pygame Zero, we’ll need quite a few frames of animation, both for the hero character and the enemies he’ll battle. For a reasonable walk cycle, we’ll need at least six frames in each direction. Any fewer than six won’t look convincing, but more frames can achieve a smoother effect. For this example, I’ve used the 3D package Poser, since it has a handy walk designer which makes generating sequences of animation much easier.

Once we have the animation frames for our characters, including a punch, kick, and any others you want to add, we need a background for the characters to walk along. The image we’re using is 2000×400 pixels, and we start the game by displaying the central part so our hero can walk either way. By detecting arrow key presses, the hero can ‘walk’ one way or the other by moving the background left and right, while cycling through the walk animation frames. Then if we detect a Q key press, we change the action string to kick; if it’s A, it’s punch. Then in our update() function, we use that action to set the Actor’s image to the indicated action frame.

Our enemy Actors will constantly walk towards the centre of the screen, and we can cycle through their walking frames the same way we do with the main hero. To give kicks and punches an effect, we put in collision checks. If the hero strikes while an enemy collides with him, we register a hit. This could be made more precise to require more skill, but once a strike’s registered, we can switch the enemy to a different status that will cause them to fall downwards and off the screen.

This sample is a starting point to demonstrate the basics of the beat-’em-up genre. With the addition of flying daggers, several levels, and a variety of bad guys, you’ll be on your way to creating a Pygame Zero version of this classic game.

The generation game

Because we’re moving the background when our hero walks left and right, we need to make sure we move our enemies with the background, otherwise they’ll look as though they’re sliding in mid-air – this also applies to any other objects that aren’t part of the background. The number of enemies can be governed in several ways: in our code, we just have a random number deciding if a new enemy will appear during each update, but we could use a predefined pattern for the enemy generation to make it a bit less random, or we use a combination of patterns and random numbers.

Here’s Mark’s code snippet, which creates a side-scrolling beat-’em-up in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code, go here.

Get your copy of Wireframe issue 32

You can read more features like this one in Wireframe issue 32, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 32 for free in PDF format.

Look how lovely and glowy it is.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a Kung-Fu Master style beat-’em-up | Wireframe #32 appeared first on Raspberry Pi.

Make a Spy Hunter-style scrolling road | Wireframe #31

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/make-a-spy-hunter-style-scrolling-road-wireframe-31/

Raspberry Pi’s own Mac Bowley shows you how to make the beginnings of a top-down driving game inspired by 1983’s Spy Hunter.

Spy Hunter, an arcade game from 1983

Spy Hunter was one of the very first games with both driving and shooting.

Spy Hunter

The 1983 arcade classic Spy Hunter put players at the wheel of a fictitious Interceptor vehicle and challenged them to navigate a vertically scrolling road, destroying enemy vehicles.

Here, I’ll show you how you can recreate the game’s scrolling road to use in your own driving games. The road will be created using the Rect class from Pygame, with the road built from stacked rectangles that are each two pixels high.

Making the scrolling road in Python

First, I create two lists; one to hold the pieces of road currently being drawn on screen, and another to hold a queue of pieces that will be added as the road scrolls. To create the scrolling road effect, each of the current pieces of road will need to move down the screen, while a new piece is added to the end of the list at position y = 0.

Pygame can schedule functions, which can then be called at set intervals – meaning I can scroll my road at a set frame rate. The scroll_road function will achieve this. First, I loop over each road piece, and move it down by two pixels. I then remove the first item in the queue list and append it to the end of the road. The Pygame clock is then set to call the function at intervals set by a frame_rate variable: mine is set to 1/60, meaning 60 frames per second.

Our top-down rolling road in Python

Our code snippet provides a solid basis for your own top-down driving game. All you need now are weapons. And a few other cars.

My road can either turn left or right, a random choice made whenever the queue is populated. Whichever way the road turns, it has to start from the same spot as the last piece in my queue. I can grab the last item in a list using -1 as an index and then store the x position; building from here will make sure my road is continuous. I use a buffer of 50 pixels to keep the road from moving off the edge of my screen – each time a turn is made, I check that the road doesn’t go beyond this point.

I want the turn amount to be random, so I’m also setting a minimum turn of 200 pixels. If this amount takes my car closer than the buffer, I’ll instead set the turn amount so that it takes it up to the buffer but no further. I do this for both directions, as well as setting a modifier to apply to my turn amount (-1 to turn left and 1 to turn right), which will save me duplicating my code. I also want to randomly choose how many pieces will be involved in my turn. Each piece is a step in the scroll, so the more pieces, the longer my turn will take. This will make sure I have a good mix of sharp and elongated turns in my road, keeping the player engaged.

Our rolling road Python code

Here’s Mac’s code snippet, which creates a winding road worthy of Spy Hunter in Python. To get it working on your system, you’ll need to install Pygame Zero. And to download the full code, go here.

Speeding up the game

To make things more exciting, the game can also be speeded up by decreasing the frame_rate variable. You could even gradually increase this over time, making the game feel more frantic the further you get.
Another improvement would be to make the turns more curvy, but make sure you’re comfortable with algebra before you do this!

Get your copy of Wireframe issue 31

You can read more features like this one in Wireframe issue 31, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 31 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Make a Spy Hunter-style scrolling road | Wireframe #31 appeared first on Raspberry Pi.

Receive AWS Developer Tools Notifications over Slack using AWS Chatbot

Post Syndicated from Anushri Anwekar original https://aws.amazon.com/blogs/devops/receive-aws-developer-tools-notifications-over-slack-using-aws-chatbot/

Developers often use Slack to communicate with each other about their code. With AWS Chatbot, you can configure notifications for developer tools resources such as repositories, build projects, deployment applications, and pipelines so that users in Slack channels are automatically notified about important events. When a deployment fails, a build succeeds, or a pull request is created, developers get notifications where they’re most likely to see and react to them.

The AWS services which currently support notifications are:

In this post, I walk you through the high-level steps for creating a notification that alerts users in a Slack channel every time a pull request is created in a CodeCommit repository.

Solution overview

You can create both the notification rule to listen for required events and the Amazon SNS topic used for notifications on the same web page. You can then configure AWS Chatbot so that notifications sent to that Amazon SNS topic appears in a Slack channel.

To set up notifications, follow the following process, as shown in the following diagram:

  1. Create a notification rule for a repository. This includes creating an Amazon SNS topic to use for notifications.
  2. Configure AWS Chatbot to send notifications from that Amazon SNS topic to a Slack channel.
  3. Test it out and enjoy receiving notifications in your team’s Slack channel.

This diagram describes the notification workflow and how impacted services are connected.

Prerequisites

To follow along with this example, you need an AWS account, an IAM user or role with administrative access, a CodeCommit repository, and a Slack channel.

Configuration steps

Step 1: Create notification rule in CodeCommit

Follow these steps to create a notification rule in CodeCommit:

1 . Select the repository in CodeCommit about which you want to be notified. In the following screenshot, I have selected a repository called Hello-Dublin. Screen-shot of the repository view

2. Select a repository for which you want to receive notifications. Choose Notify, then Create notification rule.Screen-shot of how to select option to create a notification rule

3. Provide a name for your notification rule. I suggest leaving the default Detail Type as Full. By selecting Full, you get extra information beyond what is present in the resource events. Also, you get updated information about your selected event types whenever new information is added about them.

  • For example, if you want to receive notifications whenever a comment is made on a pull request, select Basic, and your notification informs you that a comment has been made.
  • If you select Full, the notification also specifies the exact comment that was made. If the notification feature is enhanced and extra information is added to be a part of the notification, you start receiving the new information without modifying your existing notification rule.

4. In Event types, in Pull request, select Created.

5. In Targets, choose Create SNS topic. This automatically sets up a new Amazon SNS topic to use for notifications, applying a policy that allows notification events to be sent to it.

6. Finish creating the rule. Keep a note of the Amazon SNS ARN, as you need this information to configure Slack integration in the next step.

For complete step-by-step instructions for creating a notification rule, see Create a Notification Rule.

Step 2: Integrate your Amazon SNS topic with AWS Chatbot

Follow these steps to integrate your Amazon SNS topic with AWS Chatbot.

1. Open up your Slack channel. You need information about it as well as your notification rule to complete integration.

2. Open the AWS Chatbot console and choose Try the AWS Chatbot beta.

3. Choose Configure new client, then Slack, then Configure.

4. AWS Chatbot asks for permission to access your Slack workplace, as seen in the following screenshot. Once you give permission, you are asked to configure your Slack channel.

Screen-shot of a prompt about AWS Chatbot requesting permission to access the notifications Slack workspace

Step 3: Test the notification

In your repository, create a pull request. In this example, I named the pull request This is a new pull request. Watch as a notification about that event appears in your Slack channel, as seen in the following screenshot.

Example of a notification received on a Slack channel when a new pull request is created

Step 4: Clean-up

If you created notification rule just for testing purposes, you should delete the SNS topic to avoid any further charges.

Conclusion

And that’s it! You can use notifications to help developers to stay informed about the key events happening in their software development life cycle. You can set up notification rules for build projects, deployment applications, pipelines, and repositories, and stay informed about key events such as pull request creation, comments made on your code or commits, build state/phase change, deployment project status change, manual pipelines approval, or pipeline execution status change. For more information, see the notifications documentation.

Code a Boulder Dash mining game | Wireframe #30

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/code-a-boulder-dash-mining-game-wireframe-30/

Learn how to code a simple Boulder Dash homage in Python and Pygame. Mark Vanstone shows you how. 

The original Boulder Dash was marked out by some devious level design, which threatened to squash the player at every turn.

Boulder Dash

Boulder Dash first appeared in 1984 for the Commodore 64, Apple II, and the Atari 400/800. It featured an energetic gem collector called Rockford who, thanks to some rather low-resolution graphics, looked a bit like an alien. His mission was to tunnel his way through a series of caves to find gems while avoiding falling rocks dislodged by his digging. Deadly creatures also inhabited the caves which, if destroyed by dropping rocks on them, turned into gems for Rockford to collect.

The ingenious level designs were what made Boulder Dash so addictive. Gems had to be collected within a time limit to unlock the exit, but some were positioned in places that would need planning to get to, often using the physics of falling boulders to block or clear areas. Of course, the puzzles got increasingly tough as the levels progressed.

Written by Peter Liepa and Chris Gray, Boulder Dash was published by First Star Software, which still puts out new versions of the game to this day. Due to its original success, Boulder Dash was ported to all kinds of platforms, and the years since have seen no fewer than 20 new iterations of Boulder Dash, and a fair few clones, too.

Our homage to Boulder Dash running in Pygame Zero. Dig through the caves to find gems – while avoiding death from above.

Making Boulder Dash in Python

We’re going to have a look at the boulder physics aspect of the game, and make a simple level where Rockford can dig out some gems and hopefully not get flattened under an avalanche of rocks. Writing our code in Pygame Zero, we’ll automatically create an 800 by 600-size window to work with. We can make our game screen by defining a two-dimensional list, which, in this case, we will fill with soil squares and randomly position the rocks and gems.

Each location in the list matrix will have a name: either wall for the outside boundary, soil for the diggable stuff, rock for a round, moveable boulder, gem for a collectable item, and finally, rockford to symbolise our hero. We can also define an Actor for Rockford, as this will make things like switching images and tracking other properties easier.

Here’s Mark’s code, which gets an homage to Boulder Dash running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

Our draw() function is just a nested loop to iterate through the list matrix and blit to the screen whatever is indicated in each square. The Rockford Actor is then drawn over the top. We can also keep a count of how many gems have been collected and provide a congratulatory message if all of them are found. In the update() function, there are only two things we really need to worry about: the first being to check for keypresses from the player and move Rockford accordingly, and the second to check rocks to see if they need to move.

Rockford is quite easy to test for movement, as he can only move onto an empty square – a soil square or a gem square. It’s also possible for him to push a boulder if there’s an empty space on the other side. For the boulders, we need to first test if there’s an empty space below it, and if so, the boulder must move downwards. We also test to see if a boulder is on top of another boulder – if it is, the top boulder can roll off and down onto a space either to the left or the right of the one beneath.
There’s not much to add to this snippet of code to turn it into a playable game of Boulder Dash. See if you can add a timer, some monsters, and, of course, some puzzles for players to solve on each level.

Testing for movement

An important thing to notice about the process of scanning through the list matrix to test for boulder movement is that we need to read the list from the bottom upwards; otherwise, because the boulders move downwards, we may end up testing a boulder multiple times if we test from the beginning to the end of the list. Similarly, if we read the list matrix from the top down, we may end up moving a boulder down and then when reading the next row, coming across the same one again, and moving it a second time.

Get your copy of Wireframe issue 30

You can read more features like this one in Wireframe issue 30, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 30 for free in PDF format.

Make sure to follow Wireframe on Twitter and Facebook for updates and exclusive offers and giveaways. Subscribe on the Wireframe website to save up to 49% compared to newsstand pricing!

The post Code a Boulder Dash mining game | Wireframe #30 appeared first on Raspberry Pi.

Building an AWS IoT Core device using AWS Serverless and an ESP32

Post Syndicated from Moheeb Zara original https://aws.amazon.com/blogs/compute/building-an-aws-iot-core-device-using-aws-serverless-and-an-esp32/

Using a simple Arduino sketch, an AWS Serverless Application Repository application, and a microcontroller, you can build a basic serverless workflow for communicating with an AWS IoT Core device.

A microcontroller is a programmable chip and acts as the brain of an electronic device. It has input and output pins for reading and writing on digital or analog components. Those components could be sensors, relays, actuators, or various other devices. It can be used to build remote sensors, home automation products, robots, and much more. The ESP32 is a powerful low-cost microcontroller with Wi-Fi and Bluetooth built in and is used this walkthrough.

The Arduino IDE, a lightweight development environment for hardware, now includes support for the ESP32. There is a large collection of community and officially supported libraries, from addressable LED strips to spectral light analysis.

The following walkthrough demonstrates connecting an ESP32 to AWS IoT Core to allow it to publish and subscribe to topics. This means that the device can send any arbitrary information, such as sensor values, into AWS IoT Core while also being able to receive commands.

Solution overview

This post walks through deploying an application from the AWS Serverless Application Repository. This allows an AWS IoT device to be messaged using a REST endpoint powered by Amazon API Gateway and AWS Lambda. The AWS SAR application also configures an AWS IoT rule that forwards any messages published by the device to a Lambda function that updates an Amazon DynamoDB table, demonstrating basic bidirectional communication.

The last section explores how to build an IoT project with real-world application. By connecting a thermal printer module and modifying a few lines of code in the example firmware, the ESP32 device becomes an AWS IoT–connected printer.

All of this can be accomplished within the AWS Free Tier, which is necessary for the following instructions.

An example of an AWS IoT project using an ESP32, AWS IoT Core, and an Arduino thermal printer

An example of an AWS IoT project using an ESP32, AWS IoT Core, and an Arduino thermal printer.

Required steps

To complete the walkthrough, follow these steps:

  • Create an AWS IoT device.
  • Install and configure the Arduino IDE.
  • Configure and flash an ESP32 IoT device.
  • Deploying the lambda-iot-rule AWS SAR application.
  • Monitor and test.
  • Create an IoT thermal printer.

Creating an AWS IoT device

To communicate with the ESP32 device, it must connect to AWS IoT Core with device credentials. You must also specify the topics it has permissions to publish and subscribe on.

  1. In the AWS IoT console, choose Register a new thing, Create a single thing.
  2. Name the new thing. Use this exact name later when configuring the ESP32 IoT device. Leave the remaining fields set to their defaults. Choose Next.
  3.  Choose Create certificate. Only the thing cert, private key, and Amazon Root CA 1 downloads are necessary for the ESP32 to connect. Download and save them somewhere secure, as they are used when programming the ESP32 device.
  4. Choose Activate, Attach a policy.
  5. Skip adding a policy, and choose Register Thing.
  6. In the AWS IoT console side menu, choose Secure, Policies, Create a policy.
  7. Name the policy Esp32Policy. Choose the Advanced tab.
  8. Paste in the following policy template.
    {
      "Version": "2012-10-17",
      "Statement": [
        {
          "Effect": "Allow",
          "Action": "iot:Connect",
          "Resource": "arn:aws:iot:REGION:ACCOUNT_ID:client/THINGNAME"
        },
        {
          "Effect": "Allow",
          "Action": "iot:Subscribe",
          "Resource": "arn:aws:iot:REGION:ACCOUNT_ID:topicfilter/esp32/sub"
        },
    	{
          "Effect": "Allow",
          "Action": "iot:Receive",
          "Resource": "arn:aws:iot:REGION:ACCOUNT_ID:topic/esp32/sub"
        },
        {
          "Effect": "Allow",
          "Action": "iot:Publish",
          "Resource": "arn:aws:iot:REGION:ACCOUNT_ID:topic/esp32/pub"
        }
      ]
    }
  9. Replace REGION with the matching AWS Region you’re currently operating in. This can be found on the top right corner of the AWS console window.
  10.  Replace ACCOUNT_ID with your own, which can be found in Account Settings.
  11. Replace THINGNAME with the name of your device.
  12. Choose Create.
  13. In the AWS IoT console, choose Secure, Certification. Select the one created for your device and choose Actions, Attach policy.
  14. Choose Esp32Policy, Attach.

Your AWS IoT device is now configured to have permission to connect to AWS IoT Core. It can also publish to the topic esp32/pub and subscribe to the topic esp32/sub. For more information on securing devices, see AWS IoT Policies.

Installing and configuring the Arduino IDE

The Arduino IDE is an open-source development environment for programming microcontrollers. It supports a continuously growing number of platforms including most ESP32-based modules. It must be installed along with the ESP32 board definitions, MQTT library, and ArduinoJson library.

  1. Download the Arduino installer for the desired operating system.
  2. Start Arduino and open the Preferences window.
  3. For Additional Board Manager URLs, add
    https://dl.espressif.com/dl/package_esp32_index.json.
  4. Choose Tools, Board, Boards Manager.
  5. Search esp32 and install the latest version.
  6. Choose Sketch, Include Library, Manage Libraries.
  7. Search MQTT, and install the latest version by Joel Gaehwiler.
  8. Repeat the library installation process for ArduinoJson.

The Arduino IDE is now installed and configured with all the board definitions and libraries needed for this walkthrough.

Configuring and flashing an ESP32 IoT device

A collection of various ESP32 development boards.

A collection of various ESP32 development boards.

For this section, you need an ESP32 device. To check if your board is compatible with the Arduino IDE, see the boards.txt file. The following code connects to AWS IoT Core securely using MQTT, a publish and subscribe messaging protocol.

This project has been tested on the following devices:

  1. Install the required serial drivers for your device. Some boards use different USB/FTDI chips for interfacing. Here are the most commonly used with links to drivers.
  2. Open the Arduino IDE and choose File, New to create a new sketch.
  3. Add a new tab and name it secrets.h.
  4. Paste the following into the secrets file.
    #include <pgmspace.h>
    
    #define SECRET
    #define THINGNAME ""
    
    const char WIFI_SSID[] = "";
    const char WIFI_PASSWORD[] = "";
    const char AWS_IOT_ENDPOINT[] = "xxxxx.amazonaws.com";
    
    // Amazon Root CA 1
    static const char AWS_CERT_CA[] PROGMEM = R"EOF(
    -----BEGIN CERTIFICATE-----
    -----END CERTIFICATE-----
    )EOF";
    
    // Device Certificate
    static const char AWS_CERT_CRT[] PROGMEM = R"KEY(
    -----BEGIN CERTIFICATE-----
    -----END CERTIFICATE-----
    )KEY";
    
    // Device Private Key
    static const char AWS_CERT_PRIVATE[] PROGMEM = R"KEY(
    -----BEGIN RSA PRIVATE KEY-----
    -----END RSA PRIVATE KEY-----
    )KEY";
  5. Enter the name of your AWS IoT thing, as it is in the console, in the field THINGNAME.
  6. To connect to Wi-Fi, add the SSID and PASSWORD of the desired network. Note: The network name should not include spaces or special characters.
  7. The AWS_IOT_ENDPOINT can be found from the Settings page in the AWS IoT console.
  8. Copy the Amazon Root CA 1, Device Certificate, and Device Private Key to their respective locations in the secrets.h file.
  9. Choose the tab for the main sketch file, and paste the following.
    #include "secrets.h"
    #include <WiFiClientSecure.h>
    #include <MQTTClient.h>
    #include <ArduinoJson.h>
    #include "WiFi.h"
    
    // The MQTT topics that this device should publish/subscribe
    #define AWS_IOT_PUBLISH_TOPIC   "esp32/pub"
    #define AWS_IOT_SUBSCRIBE_TOPIC "esp32/sub"
    
    WiFiClientSecure net = WiFiClientSecure();
    MQTTClient client = MQTTClient(256);
    
    void connectAWS()
    {
      WiFi.mode(WIFI_STA);
      WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
    
      Serial.println("Connecting to Wi-Fi");
    
      while (WiFi.status() != WL_CONNECTED){
        delay(500);
        Serial.print(".");
      }
    
      // Configure WiFiClientSecure to use the AWS IoT device credentials
      net.setCACert(AWS_CERT_CA);
      net.setCertificate(AWS_CERT_CRT);
      net.setPrivateKey(AWS_CERT_PRIVATE);
    
      // Connect to the MQTT broker on the AWS endpoint we defined earlier
      client.begin(AWS_IOT_ENDPOINT, 8883, net);
    
      // Create a message handler
      client.onMessage(messageHandler);
    
      Serial.print("Connecting to AWS IOT");
    
      while (!client.connect(THINGNAME)) {
        Serial.print(".");
        delay(100);
      }
    
      if(!client.connected()){
        Serial.println("AWS IoT Timeout!");
        return;
      }
    
      // Subscribe to a topic
      client.subscribe(AWS_IOT_SUBSCRIBE_TOPIC);
    
      Serial.println("AWS IoT Connected!");
    }
    
    void publishMessage()
    {
      StaticJsonDocument<200> doc;
      doc["time"] = millis();
      doc["sensor_a0"] = analogRead(0);
      char jsonBuffer[512];
      serializeJson(doc, jsonBuffer); // print to client
    
      client.publish(AWS_IOT_PUBLISH_TOPIC, jsonBuffer);
    }
    
    void messageHandler(String &topic, String &payload) {
      Serial.println("incoming: " + topic + " - " + payload);
    
    //  StaticJsonDocument<200> doc;
    //  deserializeJson(doc, payload);
    //  const char* message = doc["message"];
    }
    
    void setup() {
      Serial.begin(9600);
      connectAWS();
    }
    
    void loop() {
      publishMessage();
      client.loop();
      delay(1000);
    }
  10. Choose File, Save, and give your project a name.

Flashing the ESP32

  1. Plug the ESP32 board into a USB port on the computer running the Arduino IDE.
  2. Choose Tools, Board, and then select the matching type of ESP32 module. In this case, a Sparkfun ESP32 Thing was used.
  3. Choose Tools, Port, and then select the matching port for your device.
  4. Choose Upload. Arduino reads Done uploading when the upload is successful.
  5. Choose the magnifying lens icon to open the Serial Monitor. Set the baud rate to 9600.

Keep the Serial Monitor open. When connected to Wi-Fi and then AWS IoT Core, any messages received on the topic esp32/sub are logged to this console. The device is also now publishing to the topic esp32/pub.

The topics are set at the top of the sketch. When changing or adding topics, remember to add permissions in the device policy.

// The MQTT topics that this device should publish/subscribe
#define AWS_IOT_PUBLISH_TOPIC   "esp32/pub"
#define AWS_IOT_SUBSCRIBE_TOPIC "esp32/sub"

Within this sketch, the relevant functions are publishMessage() and messageHandler().

The publishMessage() function creates a JSON object with the current time in milliseconds and the analog value of pin A0 on the device. It then publishes this JSON object to the topic esp32/pub.

void publishMessage()
{
  StaticJsonDocument<200> doc;
  doc["time"] = millis();
  doc["sensor_a0"] = analogRead(0);
  char jsonBuffer[512];
  serializeJson(doc, jsonBuffer); // print to client

  client.publish(AWS_IOT_PUBLISH_TOPIC, jsonBuffer);
}

The messageHandler() function prints out the topic and payload of any message from a subscribed topic. To see all the ways to parse JSON messages in Arduino, see the deserializeJson() example.

void messageHandler(String &topic, String &payload) {
  Serial.println("incoming: " + topic + " - " + payload);

//  StaticJsonDocument<200> doc;
//  deserializeJson(doc, payload);
//  const char* message = doc["message"];
}

Additional topic subscriptions can be added within the connectAWS() function by adding another line similar to the following.

// Subscribe to a topic
  client.subscribe(AWS_IOT_SUBSCRIBE_TOPIC);

  Serial.println("AWS IoT Connected!");

Deploying the lambda-iot-rule AWS SAR application

Now that an ESP32 device has been connected to AWS IoT, the following steps walk through deploying an AWS Serverless Application Repository application. This is a base for building serverless integration with a physical device.

  1. On the lambda-iot-rule AWS Serverless Application Repository application page, make sure that the Region is the same as the AWS IoT device.
  2. Choose Deploy.
  3. Under Application settings, for PublishTopic, enter esp32/sub. This is the topic to which the ESP32 device is subscribed. It receives messages published to this topic. Likewise, set SubscribeTopic to esp32/pub, the topic on which the device publishes.
  4. Choose Deploy.
  5. When creation of the application is complete, choose Test app to navigate to the application page. Keep this page open for the next section.

Monitoring and testing

At this stage, two Lambda functions, a DynamoDB table, and an AWS IoT rule have been deployed. The IoT rule forwards messages on topic esp32/pub to TopicSubscriber, a Lambda function, which inserts the messages on to the DynamoDB table.

  1. On the application page, under Resources, choose MyTable. This is the DynamoDB table that the TopicSubscriber Lambda function updates.
  2. Choose Items. If the ESP32 device is still active and connected, messages that it has published appear here.

The TopicPublisher Lambda function is invoked by the API Gateway endpoint and publishes to the AWS IoT topic esp32/sub.

1.     On the application page, find the Application endpoint.

2.     To test that the TopicPublisher function is working, enter the following into a terminal or command-line utility, replacing ENDPOINT with the URL from above.

curl -d '{"text":"Hello world!"}' -H "Content-Type: application/json" -X POST https://ENDPOINT/publish

Upon success, the request returns a copy of the message.

Back in the Serial Monitor, the message published to the topic esp32/sub prints out.

Creating an IoT thermal printer

With the completion of the previous steps, the ESP32 device currently logs incoming messages to the serial console.

The following steps demonstrate how the code can be modified to use incoming messages to interact with a peripheral component. This is done by wiring a thermal printer to the ESP32 in order to physically print messages. The REST endpoint from the previous section can be used as a webhook in third-party applications to interact with this device.

A wiring diagram depicting an ESP32 connected to a thermal printer.

A wiring diagram depicting an ESP32 connected to a thermal printer.

  1. Follow the product instructions for powering, wiring, and installing the correct Arduino library.
  2. Ensure that the thermal printer is working by holding the power button on the printer while connecting the power. A sample receipt prints. On that receipt, the default baud rate is specified as either 9600 or 19200.
  3. In the Arduino code from earlier, include the following lines at the top of the main sketch file. The second line defines what interface the thermal printer is connected to. &Serial2 is used to set the third hardware serial interface on the ESP32. For this example, the pins on the Sparkfun ESP32 Thing, GPIO16/GPIO17, are used for RX/TX respectively.
    #include "Adafruit_Thermal.h"
    
    Adafruit_Thermal printer(&Serial2);
  4. Replace the setup() function with the following to initialize the printer on device bootup. Change the baud rate of Serial2.begin() to match what is specified in the test print. The default is 19200.
    void setup() {
      Serial.begin(9600);
    
      // Start the thermal printer
      Serial2.begin(19200);
      printer.begin();
      printer.setSize('S');
    
      connectAWS();
    }
    
  5. Replace the messageHandler() function with the following. On any incoming message, it parses the JSON and prints the message on the thermal printer.
    void messageHandler(String &topic, String &payload) {
      Serial.println("incoming: " + topic + " - " + payload);
    
      // deserialize json
      StaticJsonDocument<200> doc;
      deserializeJson(doc, payload);
      String message = doc["message"];
    
      // Print the message on the thermal printer
      printer.println(message);
      printer.feed(2);
    }
  6. Choose Upload.
  7. After the firmware has successfully uploaded, open the Serial Monitor to confirm that the board has connected to AWS IoT.
  8. Enter the following into a command-line utility, replacing ENDPOINT, as in the previous section.
    curl -d '{"message": "Hello World!"}' -H "Content-Type: application/json" -X POST https://ENDPOINT/publish

If successful, the device prints out the message “Hello World” from the attached thermal printer. This is a fully serverless IoT printer that can be triggered remotely from a webhook. As an example, this can be used with GitHub Webhooks to print a physical readout of events.

Conclusion

Using a simple Arduino sketch, an AWS Serverless Application Repository application, and a microcontroller, this post demonstrated how to build a basic serverless workflow for communicating with a physical device. It also showed how to expand that into an IoT thermal printer with real-world applications.

With the use of AWS serverless, advanced compute and extensibility can be added to an IoT device, from machine learning to translation services and beyond. By using the Arduino programming environment, the vast collection of open-source libraries, projects, and code examples open up a world of possibilities. The next step is to explore what can be done with an Arduino and the capabilities of AWS serverless. The sample Arduino code for this project and more can be found at this GitHub repository.

Create a turn-based combat system | Wireframe #28

Post Syndicated from Ryan Lambie original https://www.raspberrypi.org/blog/create-a-turn-based-combat-system-wireframe-28/

Learn how to create the turn-based combat system found in games like Pokémon, Final Fantasy, and Undertale. Raspberry Pi’s Rik Cross shows you how.

With their emphasis on trading and collecting as well as turn-based combat, the Pokémon games helped bring RPG concepts to the masses.

In the late 1970s, high school student Richard Garriott made a little game called Akalabeth. Programmed in Applesoft BASIC, it helped set the template for the role-playing genre on computers. Even today, turn-based combat is still a common sight in games, with this autumn’s Pokémon Sword and Shield revolving around a battle system which sees opponents take turns to plan and execute attacks or defensive moves.

The turn-based combat system in this article is text-only, and works by allowing players to choose to defend against or attack their opponent in turn. The battle ends when only one player has some health remaining.

Each Player taking part in the battle is added to the static players list as it’s created. Players have a name, a health value (initially set to 100) and a Boolean defending value (initially set to False) to indicate whether a player is using their shield. Players also have an inputmethod attribute, which is the function used for getting player input for making various choices in the game. This function is passed to the object when created, and means that we can have human players that give their input through the keyboard, as well as computer players that make choices (in our case simply by making a random choice between the available options).

Richard Garriott’s Akalabeth laid the groundwork for Ultima, and was one of the earliest CRPGs.

A base Action class specifies an action owner and an opponent, as well as an execute() method which has no effect on the game. Subclasses of the base class override this execute() method to specify the effect the action has on the owner and/or the opponent of the action. As a basic example, two actions have been created: Defend, which sets the owner’s defending attribute to True, and Attack, which sets the owner’s defending attribute to False, and lowers the opponent’s health by a random amount depending on whether or not they are defending.

Players take turns to choose a single action to perform in the battle, starting with the human ‘Hero’ player. The choose_action() method is used to decide what to do next (in this case either attack or defend), as well as an opponent if the player has chosen to attack. A player can only be selected as an opponent if they have a health value greater than 0, and are therefore still in the game. This choose_action() method returns an Action, which is then executed using its execute() method. A few time.sleep() commands have also been thrown in here  to ramp up the suspense!

After each player has had their turn, a check is done to make sure that at least two players still have a health value greater than 0, and therefore that the battle can continue. If so, the static get_next_player() method finds the next player still in the game to take their turn in the battle, otherwise, the game ends and the winner is announced.

Our example battle can be easily extended in lots of interesting ways. The AI for choosing an action could also be made more sophisticated, by looking at opponents’ health or defending attributes before choosing an action. You could also give each action a ‘cost’, and give players a number of action ‘points’ per turn. Chosen actions would be added to a list, until all of the points have been used. These actions would then be executed one after the other, before moving on to the next player’s turn.

Here’s Rik’s code, which gets a simple turn-based combat system running in Python. To get it working on your system, you’ll first need to install Pygame Zero. And to download the full code, go here.

You can read more features like this one in Wireframe issue 28, available now at Tesco, WHSmith, all good independent UK newsagents, and the Raspberry Pi Store, Cambridge.

Or you can buy Wireframe directly from Raspberry Pi Press — delivery is available worldwide. And if you’d like a handy digital version of the magazine, you can also download issue 28 for free in PDF format.

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