# The Effects of the Spectre and Meltdown Vulnerabilities

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/01/the_effects_of_3.html

On January 3, the world learned about a series of major security vulnerabilities in modern microprocessors. Called Spectre and Meltdown, these vulnerabilities were discovered by several different researchers last summer, disclosed to the microprocessors’ manufacturers, and patched­ — at least to the extent possible.

This news isn’t really any different from the usual endless stream of security vulnerabilities and patches, but it’s also a harbinger of the sorts of security problems we’re going to be seeing in the coming years. These are vulnerabilities in computer hardware, not software. They affect virtually all high-end microprocessors produced in the last 20 years. Patching them requires large-scale coordination across the industry, and in some cases drastically affects the performance of the computers. And sometimes patching isn’t possible; the vulnerability will remain until the computer is discarded.

Spectre and Meltdown aren’t anomalies. They represent a new area to look for vulnerabilities and a new avenue of attack. They’re the future of security­ — and it doesn’t look good for the defenders.

Modern computers do lots of things at the same time. Your computer and your phone simultaneously run several applications — ­or apps. Your browser has several windows open. A cloud computer runs applications for many different computers. All of those applications need to be isolated from each other. For security, one application isn’t supposed to be able to peek at what another one is doing, except in very controlled circumstances. Otherwise, a malicious advertisement on a website you’re visiting could eavesdrop on your banking details, or the cloud service purchased by some foreign intelligence organization could eavesdrop on every other cloud customer, and so on. The companies that write browsers, operating systems, and cloud infrastructure spend a lot of time making sure this isolation works.

Both Spectre and Meltdown break that isolation, deep down at the microprocessor level, by exploiting performance optimizations that have been implemented for the past decade or so. Basically, microprocessors have become so fast that they spend a lot of time waiting for data to move in and out of memory. To increase performance, these processors guess what data they’re going to receive and execute instructions based on that. If the guess turns out to be correct, it’s a performance win. If it’s wrong, the microprocessors throw away what they’ve done without losing any time. This feature is called speculative execution.

Spectre and Meltdown attack speculative execution in different ways. Meltdown is more of a conventional vulnerability; the designers of the speculative-execution process made a mistake, so they just needed to fix it. Spectre is worse; it’s a flaw in the very concept of speculative execution. There’s no way to patch that vulnerability; the chips need to be redesigned in such a way as to eliminate it.

Since the announcement, manufacturers have been rolling out patches to these vulnerabilities to the extent possible. Operating systems have been patched so that attackers can’t make use of the vulnerabilities. Web browsers have been patched. Chips have been patched. From the user’s perspective, these are routine fixes. But several aspects of these vulnerabilities illustrate the sorts of security problems we’re only going to be seeing more of.

First, attacks against hardware, as opposed to software, will become more common. Last fall, vulnerabilities were discovered in Intel’s Management Engine, a remote-administration feature on its microprocessors. Like Spectre and Meltdown, they affected how the chips operate. Looking for vulnerabilities on computer chips is new. Now that researchers know this is a fruitful area to explore, security researchers, foreign intelligence agencies, and criminals will be on the hunt.

Second, because microprocessors are fundamental parts of computers, patching requires coordination between many companies. Even when manufacturers like Intel and AMD can write a patch for a vulnerability, computer makers and application vendors still have to customize and push the patch out to the users. This makes it much harder to keep vulnerabilities secret while patches are being written. Spectre and Meltdown were announced prematurely because details were leaking and rumors were swirling. Situations like this give malicious actors more opportunity to attack systems before they’re guarded.

Third, these vulnerabilities will affect computers’ functionality. In some cases, the patches for Spectre and Meltdown result in significant reductions in speed. The press initially reported 30%, but that only seems true for certain servers running in the cloud. For your personal computer or phone, the performance hit from the patch is minimal. But as more vulnerabilities are discovered in hardware, patches will affect performance in noticeable ways.

And then there are the unpatchable vulnerabilities. For decades, the computer industry has kept things secure by finding vulnerabilities in fielded products and quickly patching them. Now there are cases where that doesn’t work. Sometimes it’s because computers are in cheap products that don’t have a patch mechanism, like many of the DVRs and webcams that are vulnerable to the Mirai (and other) botnets — ­groups of Internet-connected devices sabotaged for coordinated digital attacks. Sometimes it’s because a computer chip’s functionality is so core to a computer’s design that patching it effectively means turning the computer off. This, too, is becoming more common.

Increasingly, everything is a computer: not just your laptop and phone, but your car, your appliances, your medical devices, and global infrastructure. These computers are and always will be vulnerable, but Spectre and Meltdown represent a new class of vulnerability. Unpatchable vulnerabilities in the deepest recesses of the world’s computer hardware is the new normal. It’s going to leave us all much more vulnerable in the future.

This essay previously appeared on TheAtlantic.com.

# Eevee gained 2791 experience points

Post Syndicated from Eevee original https://eev.ee/blog/2018/01/15/eevee-gained-2791-experience-points/

Eevee grew to level 31!

A year strongly defined by mixed success! Also, a lot of video games.

I ran three game jams, resulting in a total of 157 games existing that may not have otherwise, which is totally mindblowing?!

For GAMES MADE QUICK???, glip and I made NEON PHASE, a short little exploratory platformer. Honestly, I should give myself more credit for this and the rest of the LÖVE games I’ve based on the same codebase — I wove a physics engine (and everything else!) from scratch and it has held up remarkably well for a variety of different uses.

I successfully finished an HD version of Isaac’s Descent using my LÖVE engine, though it doesn’t have anything new over the original and I’ve only released it as a tech demo on Patreon.

For Strawberry Jam (NSFW!) we made fox flux (slightly NSFW!), which felt like a huge milestone: the first game where I made all the art! I mean, not counting Isaac’s Descent, which was for a very limited platform. It’s a pretty arbitrary milestone, yes, but it feels significant. I’ve been working on expanding the game into a longer and slightly less buggy experience, but the art is taking the longest by far. I must’ve spent weeks on player sprites alone.

We then set about working on Bolthaven, a sequel of sorts to NEON PHASE, and got decently far, and then abandond it. Oops.

We then started a cute little PICO-8 game, and forgot about it. Oops.

I was recruited to help with Chaos Composer, a more ambitious game glip started with someone else in Unity. I had to get used to Unity, and we squabbled a bit, but the game is finally about at the point where it’s “playable” and “maps” can be designed? It’s slightly on hold at the moment while we all finish up some other stuff, though.

We made a birthday game for two of our friends whose birthdays were very close together! Only they got to see it.

For Ludum Dare 38, we made Lunar Depot 38, a little “wave shooter” or whatever you call those? The AI is pretty rough, seeing as this was the first time I’d really made enemies and I had 72 hours to figure out how to do it, but I still think it’s pretty fun to play and I love the circular world.

I made Roguelike Simulator as an experiment with making something small and quick with a simple tool, and I had a lot of fun! I definitely want to do more stuff like this in the future.

And now we’re working on a game about Star Anise, my cat’s self-insert, which is looking to have more polish and depth than anything we’ve done so far! We’ve definitely come a long way in a year.

Somewhere along the line, I put out a call for a “potluck” project, where everyone would give me sprites of a given size without knowing what anyone else had contributed, and I would then make a game using only those sprites. Unfortunately, that stalled a few times: I tried using the Phaser JS library, but we didn’t get along; I tried LÖVE, but didn’t know where to go with the game; and then I decided to use this as an experiment with procedural generation, and didn’t get around to it. I still feel bad that everyone did work for me and I didn’t follow through, but I don’t know whether this will ever become a game.

veekun, alas, consumed months of my life. I finally got Sun and Moon loaded, but it took weeks of work since I was basically reinventing all the tooling we’d ever had from scratch, without even having most of that tooling available as a reference. It was worth it in the end, at least: Ultra Sun and Ultra Moon only took a few days to get loaded. But veekun itself is still missing some obvious Sun/Moon features, and the whole site needs an overhaul, and I just don’t know if I want to dedicate that much time to it when I have so much other stuff going on that’s much more interesting to me right now.

I finally turned my blog into more of a website, giving it a neat front page that lists a bunch of stuff I’ve done. I made a release category at last, though I’m still not quite in the habit of using it.

I wrote some blog posts, of course! I think the most interesting were JavaScript got better while I wasn’t looking and Object models. I was also asked to write a couple pieces for money for a column that then promptly shut down.

On a whim, I made a set of Eevee mugshots for Doom, which I think is a decent indication of my (pixel) art progress over the year?

I started idchoppers, a Doom parsing and manipulation library written in Rust, though it didn’t get very far and I’ve spent most of the time fighting with Rust because it won’t let me implement all my extremely bad ideas. It can do a couple things, at least, like flip maps very quickly and render maps to SVG.

I did toy around with music a little, but not a lot.

I wrote two short twines for Flora. They’re okay. I’m working on another; I think it’ll be better.

I didn’t do a lot of art overall, at least compared to the two previous years; most of my art effort over the year has gone into fox flux, which requires me to learn a whole lot of things. I did dip my toes into 3D modelling, most notably producing my current Twitter banner as well as this cool Star Anise animation. I wouldn’t mind doing more of that; maybe I’ll even try to make a low-poly pixel-textured 3D game sometime.

I restarted my book with a much better concept, though so far I’ve only written about half a chapter. Argh. I see that the vast majority of the work was done within the span of a single week, which is bad since that means I only worked on it for a week, but good since that means I can actually do a pretty good amount of work in only a week. I also did a lot of squabbling with tooling, which is hopefully mostly out of the way now.

My computer broke? That was an exciting week.

A lot of stuff, but the year as a whole still feels hit or miss. All the time I spent on veekun feels like a black void in the middle of the year, which seems like a good sign that I maybe don’t want to pour even more weeks into it in the near future.

Mostly, I want to do: more games, more art, more writing, more music.

I want to try out some tiny game making tools and make some tiny games with them — partly to get exposure to different things, partly to get more little ideas out into the world regularly, and partly to get more practice at letting myself have ideas. I have a couple tools in mind and I guess I’ll aim at a microgame every two months or so? I’d also like to finish the expanded fox flux by the end of the year, of course, though at the moment I can’t even gauge how long it might take.

I seriously lapsed on drawing last year, largely because fox flux pixel art took me so much time. So I want to draw more, and I want to get much faster at pixel art. It would probably help if I had a more concrete goal for drawing, so I might try to draw some short comics and write a little visual novel or something, which would also force me to aim for consistency.

I want to work on my book more, of course, but I also want to try my hand at a bit more fiction. I’ve had a blast writing dialogue for our games! I just shy away from longer-form writing for some reason — which seems ridiculous when a large part of my audience found me through my blog. I do think I’ve had some sort of breakthrough in the last month or two; I suddenly feel a good bit more confident about writing in general and figuring out what I want to say? One recent post I know I wrote in a single afternoon, which virtually never happens because I keep rewriting and rearranging stuff. Again, a visual novel would be a good excuse to practice writing fiction without getting too bogged down in details.

And, ah, music. I shy heavily away from music, since I have no idea what I’m doing, and also I seem to spend a lot of time fighting with tools. (Surprise.) I tried out SunVox for the first time just a few days ago and have been enjoying it quite a bit for making sound effects, so I might try it for music as well. And once again, visual novel background music is a pretty low-pressure thing to compose for. Hell, visual novels are small games, too, so that checks all the boxes. I guess I’ll go make a visual novel.

Here’s to twenty gayteen!

# Weekly roundup: Happy birthday

Post Syndicated from Eevee original https://eev.ee/dev/2018/01/15/weekly-roundup-happy-birthday/

It was my birthday! I need to write a birthday post argh.

• anise!!: Surprise! Mostly Anise. I refactored dialogue to be a bit less of a hairball; started making item pickups actually work; decided to reverse a former decision and expand the world a little bit (which unfortunately means the world map doesn’t quite fit all on the screen at once, oh well); finally got around to making animated tiles work (!!!); experimented with making sound effects in SunVox, with mixed success; and just general working on level design which takes incredibly far much longer than I ever expected.

• misc: I wrote a userscript to highlight the game being currently played at GDQ, though it’s not quite so useful now that GDQ is over.

I realize I don’t really know where a tiny oneoff thing like this should live, and I’ve left a trail of a good few of them. Hmm. I guess I could’ve written a release post for it, but it also seems like it should be in an index of stuff somewhere…?

• ???: ???

# Physics cheats

Post Syndicated from Eevee original https://eev.ee/blog/2018/01/06/physics-cheats/

something about how we tweak physics to “work” better in games?

Ho ho! Work. Get it? Like in physics…?

## Hitboxes

Hitbox” is perhaps not the most accurate term, since the shape used for colliding with the environment and the shape used for detecting damage might be totally different. They’re usually the same in simple platformers, though, and that’s what most of my games have been.

The hitbox is the biggest physics fudge by far, and it exists because of a single massive approximation that (most) games make: you’re controlling a single entity in the abstract, not a physical body in great detail.

That is: when you walk with your real-world meat shell, you perform a complex dance of putting one foot in front of the other, a motion you spent years perfecting. When you walk in a video game, you press a single “walk” button. Your avatar may play an animation that moves its legs back and forth, but since you’re not actually controlling the legs independently (and since simulating them is way harder), the game just treats you like a simple shape. Fairly often, this is a box, or something very box-like.

Since the player has no direct control over the exact placement of their limbs, it would be slightly frustrating to have them collide with the world. This is especially true in cases like the above, where the tail and left ear protrude significantly out from the main body. If that Eevee wanted to stand against a real-world wall, she would simply tilt her ear or tail out of the way, so there’s no reason for the ear to block her from standing against a game wall. To compensate for this, the ear and tail are left out of the collision box entirely and will simply jut into a wall if necessary — a goofy affordance that’s so common it doesn’t even register as unusual. As a bonus (assuming this same box is used for combat), she won’t take damage from projectiles that merely graze past an ear.

(One extra consideration for sprite games in particular: the hitbox ought to be horizontally symmetric around the sprite’s pivot — i.e. the point where the entity is truly considered to be standing — so that the hitbox doesn’t abruptly move when the entity turns around!)

### Corners

Treating the player (and indeed most objects) as a box has one annoying side effect: boxes have corners. Corners can catch on other corners, even by a single pixel. Real-world bodies tend to be a bit rounder and squishier and this can tolerate grazing a corner; even real-world boxes will simply rotate a bit.

Ah, but in our faux physics world, we generally don’t want conscious actors (such as the player) to rotate, even with a realistic physics simulator! Real-world bodies are made of parts that will generally try to keep you upright, after all; you don’t tilt back and forth much.

One way to handle corners is to simply remove them from conscious actors. A hitbox doesn’t have to be a literal box, after all. A popular alternative — especially in Unity where it’s a standard asset — is the pill-shaped capsule, which has semicircles/hemispheres on the top and bottom and a cylindrical body in 3D. No corners, no problem.

Of course, that introduces a new problem: now the player can’t balance precariously on edges without their rounded bottom sliding them off. Alas.

If you’re stuck with corners, then, you may want to use a corner bump, a term I just made up. If the player would collide with a corner, but the collision is only by a few pixels, just nudge them to the side a bit and carry on.

When the corner is horizontal, this creates stairs! This is, more or less kinda, how steps work in Doom: when the player tries to cross from one sector into another, if the height difference is 24 units or less, the game simply bumps them upwards to the height of the new floor and lets them continue on.

Implementing this in a game without Doom’s notion of sectors is a little trickier. In fact, I still haven’t done it. Collision detection based on rejection gets it for free, kinda, but it’s not very deterministic and it breaks other things. But that’s a whole other post.

## Gravity

Gravity is pretty easy. Everything accelerates downwards all the time. What’s interesting are the exceptions.

### Jumping

Jumping is a giant hack.

Think about how actual jumping works: you tense your legs, which generally involves bending your knees first, and then spring upwards. In a platformer, you can just leap whenever you feel like it, which is nonsense. Also you go like twenty feet into the air?

Worse, most platformers allow variable-height jumping, where your jump is lower if you let go of the jump button while you’re in the air. Normally, one would expect to have to decide how much force to put into the jump beforehand.

But of course this is about convenience of controls: when jumping is your primary action, you want to be able to do it immediately, without any windup for how high you want to jump.

(And then there’s double jumping? Come on.)

Air control is a similar phenomenon: usually you’d jump in a particular direction by controlling how you push off the ground with your feet, but in a video game, you don’t have feet! You only have the box. The compromise is to let you control your horizontal movement to a limit degree in midair, even though that doesn’t make any sense. (It’s way more fun, though, and overall gives you more movement options, which are good to have in an interactive medium.)

Air control also exposes an obvious place that game physics collide with the realistic model of serious physics engines. I’ve mentioned this before, but: if you use Real Physics™ and air control yourself into a wall, you might find that you’ll simply stick to the wall until you let go of the movement buttons. Why? Remember, player movement acts as though an external force were pushing you around (and from the perspective of a Real™ physics engine, this is exactly how you’d implement it) — so air-controlling into a wall is equivalent to pushing a book against a wall with your hand, and the friction with the wall holds you in place. Oops.

### Ground sticking

Another place game physics conflict with physics engines is with running to the top of a slope. On a real hill, of course, you land on top of the slope and are probably glad of it; slopes are hard to climb!

In a video game, you go flying. Because you’re a box. With momentum. So you hit the peak and keep going in the same direction. Which is diagonally upwards.

### Projectiles

To make them more predictable, projectiles generally aren’t subject to gravity, at least as far as I’ve seen. The real world does not have such an exemption. The real world imposes gravity even on sniper rifles, which in a video game are often implemented as an instant trace unaffected by anything in the world because the bullet never actually exists in the world.

## Resistance

Ah. Welcome to hell.

### Water

Water is an interesting case, and offhand I don’t know the gritty details of how games implement it. In the real world, water applies a resistant drag force to movement — and that force is proportional to the square of velocity, which I’d completely forgotten until right now. I am almost positive that no game handles that correctly. But then, in real-world water, you can push against the water itself for movement, and games don’t simulate that either. What’s the rough equivalent?

The Sonic Physics Guide suggests that Sonic handles it by basically halving everything: acceleration, max speed, friction, etc. When Sonic enters water, his speed is cut; when Sonic exits water, his speed is increased.

That last bit feels validating — I could swear Metroid Prime did the same thing, and built my own solution around it, but couldn’t remember for sure. It makes no sense, of course, for a jump to become faster just because you happened to break the surface of the water, but it feels fantastic.

The thing I did was similar, except that I didn’t want to add a multiplier in a dozen places when you happen to be underwater (and remember which ones need it to be squared, etc.). So instead, I calculate everything completely as normal, so velocity is exactly the same as it would be on dry land — but the distance you would move gets halved. The effect seems to be pretty similar to most platformers with water, at least as far as I can tell. It hasn’t shown up in a published game and I only added this fairly recently, so I might be overlooking some reason this is a bad idea.

(One reason that comes to mind is that velocity is now a little white lie while underwater, so anything relying on velocity for interesting effects might be thrown off. Or maybe that’s correct, because velocity thresholds should be halved underwater too? Hm!)

Notably, air is also a fluid, so it should behave the same way (just with different constants). I definitely don’t think any games apply air drag that’s proportional to the square of velocity.

### Friction

Friction is, in my experience, a little handwaved. Probably because real-world friction is so darn complicated.

Consider that in the real world, we want very high friction on the surfaces we walk on — shoes and tires are explicitly designed to increase it, even. We move by bracing a back foot against the ground and using that to push ourselves forward, so we want the ground to resist our push as much as possible.

In a game world, we are a box. We move by being pushed by some invisible outside force, so if the friction between ourselves and the ground is too high, we won’t be able to move at all! That’s complete nonsense physically, but it turns out to be handy in some cases — for example, highish friction can simulate walking through deep mud, which should be difficult due to fluid drag and low friction.

But the best-known example of the fakeness of game friction is video game ice. Walking on real-world ice is difficult because the low friction means low grip; your feet are likely to slip out from under you, and you’ll simply fall down and have trouble moving at all. In a video game, you can’t fall down, so you have the opposite experience: you spend most of your time sliding around uncontrollably. Yet ice is so common in video games (and perhaps so uncommon in places I’ve lived) that I, at least, had never really thought about this disparity until an hour or so ago.

### Game friction vs real-world friction

Real-world friction is a force. It’s the normal force (which is the force exerted by the object on the surface) times some constant that depends on how the two materials interact.

Force is mass times acceleration, and platformers often ignore mass, so friction ought to be an acceleration — applied against the object’s movement, but never enough to push it backwards.

I haven’t made any games where variable friction plays a significant role, but my gut instinct is that low friction should mean the player accelerates more slowly but has a higher max speed, and high friction should mean the opposite. I see from my own source code that I didn’t even do what I just said, so let’s defer to some better-made and well-documented games: Sonic and Doom.

In Sonic, friction is a fixed value subtracted from the player’s velocity (regardless of direction) each tic. Sonic has a fixed framerate, so the units are really pixels per tic squared (i.e. acceleration), multiplied by an implicit 1 tic per tic. So far, so good.

But Sonic’s friction only applies if the player isn’t pressing or . Hang on, that isn’t friction at all; that’s just deceleration! That’s equivalent to jogging to a stop. If friction were lower, Sonic would take longer to stop, but otherwise this is only tangentially related to friction.

(In fairness, this approach would decently emulate friction for non-conscious sliding objects, which are never going to be pressing movement buttons. Also, we don’t have the Sonic source code, and the name “friction” is a fan invention; the Sonic Physics Guide already uses “deceleration” to describe the player’s acceleration when turning around.)

Okay, let’s try Doom. In Doom, the default friction is 90.625%.

Hang on, what?

Yes, in Doom, friction is a multiplier applied every tic. Doom runs at 35 tics per second, so this is a multiplier of 0.032 per second. Yikes!

This isn’t anything remotely like real friction, but it’s much easier to implement. With friction as acceleration, the game has to know both the direction of movement (so it can apply friction in the opposite direction) and the magnitude (so it doesn’t overshoot and launch the object in the other direction). That means taking a semi-costly square root and also writing extra code to cap the amount of friction. With a multiplier, neither is necessary; just multiply the whole velocity vector and you’re done.

There are some downsides. One is that objects will never actually stop, since multiplying by 3% repeatedly will never produce a result of zero — though eventually the speed will become small enough to either slip below a “minimum speed” threshold or simply no longer fit in a float representation. Another is that the units are fairly meaningless: with Doom’s default friction of 90.625%, about how long does it take for the player to stop? I have no idea, partly because “stop” is ambiguous here! If friction were an acceleration, I could divide it into the player’s max speed to get a time.

All that aside, what are the actual effects of changing Doom’s friction? What an excellent question that’s surprisingly tricky to answer. (Note that friction can’t be changed in original Doom, only in the Boom port and its derivatives.) Here’s what I’ve pieced together.

Doom’s “friction” is really two values. “Friction” itself is a multiplier applied to moving objects on every tic, but there’s also a move factor which defaults to $$\frac{1}{32} = 0.03125$$ and is derived from friction for custom values.

Every tic, the player’s velocity is multiplied by friction, and then increased by their speed times the move factor.

$$v(n) = v(n – 1) \times friction + speed \times move factor$$

Eventually, the reduction from friction will balance out the speed boost. That happens when $$v(n) = v(n – 1)$$, so we can rearrange it to find the player’s effective max speed:

$$v = v \times friction + speed \times move factor \\ v – v \times friction = speed \times move factor \\ v = speed \times \frac{move factor}{1 – friction}$$

For vanilla Doom’s move factor of 0.03125 and friction of 0.90625, that becomes:

$$v = speed \times \frac{\frac{1}{32}}{1 – \frac{29}{32}} = speed \times \frac{\frac{1}{32}}{\frac{3}{32}} = \frac{1}{3} \times speed$$

Curiously, “speed” is three times the maximum speed an actor can actually move. Doomguy’s run speed is 50, so in practice he moves a third of that, or 16⅔ units per tic. (Of course, this isn’t counting SR40, a bug that lets Doomguy run ~40% faster than intended diagonally.)

So now, what if you change friction? Even more curiously, the move factor is calculated completely differently depending on whether friction is higher or lower than the default Doom amount:

$$move factor = \begin{cases} \frac{133 – 128 \times friction}{544} &≈ 0.244 – 0.235 \times friction & \text{ if } friction \ge \frac{29}{32} \\ \frac{81920 \times friction – 70145}{1048576} &≈ 0.078 \times friction – 0.067 & \text{ otherwise } \end{cases}$$

That’s pretty weird? Complicating things further is that low friction (which means muddy terrain, remember) has an extra multiplier on its move factor, depending on how fast you’re already going — the idea is apparently that you have a hard time getting going, but it gets easier as you find your footing. The extra multiplier maxes out at 8, which makes the two halves of that function meet at the vanilla Doom value.

That very top point corresponds to the move factor from the original game. So no matter what you do to friction, the move factor becomes lower. At 0.85 and change, you can no longer move at all; below that, you move backwards.

From the formula above, it’s easy to see what changes to friction and move factor will do to Doomguy’s stable velocity. Move factor is in the numerator, so increasing it will increase stable velocity — but it can’t increase, so stable velocity can only ever decrease. Friction is in the denominator, but it’s subtracted from 1, so increasing friction will make the denominator a smaller value less than 1, i.e. increase stable velocity. Combined, we get this relationship between friction and stable velocity.

As friction approaches 1, stable velocity grows without bound. This makes sense, given the definition of $$v(n)$$ — if friction is 1, the velocity from the previous tic isn’t reduced at all, so we just keep accelerating freely.

All of this is why I’m wary of using multipliers.

Anyway, this leaves me with one last question about the effects of Doom’s friction: how long does it take to reach stable velocity? Barring precision errors, we’ll never truly reach stable velocity, but let’s say within 5%. First we need a closed formula for the velocity after some number of tics. This is a simple recurrence relation, and you can write a few terms out yourself if you want to be sure this is right.

$$v(n) = v_0 \times friction^n + speed \times move factor \times \frac{friction^n – 1}{friction – 1}$$

Our initial velocity is zero, so the first term disappears. Set this equal to the stable formula and solve for n:

$$speed \times move factor \times \frac{friction^n – 1}{friction – 1} = (1 – 5\%) \times speed \times \frac{move factor}{1 – friction} \\ friction^n – 1 = -(1 – 5\%) \\ n = \frac{\ln 5\%}{\ln friction}$$

Speed” and move factor disappear entirely, which makes sense, and this is purely a function of friction (and how close we want to get). For vanilla Doom, that comes out to 30.4, which is a little less than a second. For other values of friction:

As friction increases (which in Doom terms means the surface is more slippery), it takes longer and longer to reach stable speed, which is in turn greater and greater. For lesser friction (i.e. mud), stable speed is lower, but reached fairly quickly. (Of course, the extra “getting going” multiplier while in mud adds some extra time here, but including that in the graph is a bit more complicated.)

I think this matches with my instincts above. How fascinating!

What’s that? This is way too much math and you hate it? Then don’t use multipliers in game physics.

## Uh

That was a hell of a diversion!

I guess the goofiest stuff in basic game physics is really just about mapping player controls to in-game actions like jumping and deceleration; the rest consists of hacks to compensate for representing everything as a box.

# Spectre and Meltdown Attacks

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/01/spectre_and_mel.html

After a week or so of rumors, everyone is now reporting about the Spectre and Meltdown attacks against pretty much every modern processor out there.

These are side-channel attacks where one process can spy on other processes. They affect computers where an untrusted browser window can execute code, phones that have multiple apps running at the same time, and cloud computing networks that run lots of different processes at once. Fixing them either requires a patch that results in a major performance hit, or is impossible and requires a re-architecture of conditional execution in future CPU chips.

I’ll be writing something for publication over the next few days. This post is basically just a link repository.

EDITED TO ADD: Good technical explanation. And a Slashdot thread.

EDITED TO ADD (1/5): Another good technical description. And how the exploits work through browsers. A rundown of what vendors are doing. Nicholas Weaver on its effects on individual computers.

EDITED TO ADD (1/7): xkcd.

EDITED TO ADD (1/10): Another good technical description.

# Privilege escalation via eBPF in Linux 4.9 and beyond

Post Syndicated from jake original https://lwn.net/Articles/742170/rss

Jann Horn has reported eight bugs in the
eBPF verifier, one for the 4.9 kernel and seven introduced in 4.14, to the
oss-security mailing list. Some
of these bugs result in eBPF programs being able to read and write arbitrary
kernel memory, thus can be used for a variety of ill effects, including
privilege escalation. As Ben Hutchings notes,
one mitigation would be to disable unprivileged access to BPF using the
following sysctl:
kernel.unprivileged_bpf_disabled=1. More information can also be found
in this Project
Zero bug entry
. The fixes are not yet in the mainline tree, but are in
the netdev tree. Hutchings goes on to say: “There is a public
exploit that uses several of these bugs to get root privileges. It doesn’t
work as-is on stretch [Debian 9] with the Linux 4.9 kernel, but is easy to adapt. I
recommend applying the above mitigation as soon as possible to all systems
running Linux 4.4 or later.

# The deal with Bitcoin

Post Syndicated from Michal Zalewski original http://lcamtuf.blogspot.com/2017/12/the-deal-with-bitcoin.html

♪ Used to have a little now I have a lot
I’m still, I’m still Jenny from the block
chain ♪

For all that has been written about Bitcoin and its ilk, it is curious that the focus is almost solely what the cryptocurrencies are supposed to be. Technologists wax lyrical about the potential for blockchains to change almost every aspect of our lives. Libertarians and paleoconservatives ache for the return to “sound money” that can’t be conjured up at the whim of a bureaucrat. Mainstream economists wag their fingers, proclaiming that a proper currency can’t be deflationary, that it must maintain a particular velocity, or that the government must be able to nip crises of confidence in the bud. And so on.

Much of this may be true, but the proponents of cryptocurrencies should recognize that an appeal to consequences is not a guarantee of good results. The critics, on the other hand, would be best served to remember that they are drawing far-reaching conclusions about the effects of modern monetary policies based on a very short and tumultuous period in history.

In this post, my goal is to ditch most of the dogma, talk a bit about the origins of money – and then see how “crypto” fits the bill.

### 1. The prehistory of currencies

The emergence of money is usually explained in a very straightforward way. You know the story: a farmer raised a pig, a cobbler made a shoe. The cobbler needed to feed his family while the farmer wanted to keep his feet warm – and so they met to exchange the goods on mutually beneficial terms. But as the tale goes, the barter system had a fatal flaw: sometimes, a farmer wanted a cooking pot, a potter wanted a knife, and a blacksmith wanted a pair of pants. To facilitate increasingly complex, multi-step exchanges without requiring dozens of people to meet face to face, we came up with an abstract way to represent value – a shiny coin guaranteed to be accepted by every tradesman.

It is a nice parable, but it probably isn’t very true. It seems far more plausible that early societies relied on the concept of debt long before the advent of currencies: an informal tally or a formal ledger would be used to keep track of who owes what to whom. The concept of debt, closely associated with one’s trustworthiness and standing in the community, would have enabled a wide range of economic activities: debts could be paid back over time, transferred, renegotiated, or forgotten – all without having to engage in spot barter or to mint a single coin. In fact, such non-monetary, trust-based, reciprocal economies are still common in closely-knit communities: among families, neighbors, coworkers, or friends.

In such a setting, primitive currencies probably emerged simply as a consequence of having a system of prices: a cow being worth a particular number of chickens, a chicken being worth a particular number of beaver pelts, and so forth. Formalizing such relationships by settling on a single, widely-known unit of account – say, one chicken – would make it more convenient to transfer, combine, or split debts; or to settle them in alternative goods.

Contrary to popular belief, for communal ledgers, the unit of account probably did not have to be particularly desirable, durable, or easy to carry; it was simply an accounting tool. And indeed, we sometimes run into fairly unusual units of account even in modern times: for example, cigarettes can be the basis of a bustling prison economy even when most inmates don’t smoke and there are not that many packs to go around.

### 2. The age of commodity money

In the end, the development of coinage might have had relatively little to do with communal trade – and far more with the desire to exchange goods with strangers. When dealing with a unfamiliar or hostile tribe, the concept of a chicken-denominated ledger does not hold up: the other side might be disinclined to honor its obligations – and get away with it, too. To settle such problematic trades, we needed a “spot” medium of exchange that would be easy to carry and authenticate, had a well-defined value, and a near-universal appeal. Throughout much of the recorded history, precious metals – predominantly gold and silver – proved to fit the bill.

In the most basic sense, such commodities could be seen as a tool to reconcile debts across societal boundaries, without necessarily replacing any local units of account. An obligation, denominated in some local currency, would be created on buyer’s side in order to procure the metal for the trade. The proceeds of the completed transaction would in turn allow the seller to settle their own local obligations that arose from having to source the traded goods. In other words, our wondrous chicken-denominated ledgers could coexist peacefully with gold – and when commodity coinage finally took hold, it’s likely that in everyday trade, precious metals served more as a useful abstraction than a precise store of value. A “silver chicken” of sorts.

Still, the emergence of commodity money had one interesting side effect: it decoupled the unit of debt – a “claim on the society”, in a sense – from any moral judgment about its origin. A piece of silver would buy the same amount of food, whether earned through hard labor or won in a drunken bet. This disconnect remains a central theme in many of the debates about social justice and unfairly earned wealth.

### 3. The State enters the game

If there is one advantage of chicken ledgers over precious metals, it’s that all chickens look and cluck roughly the same – something that can’t be said of every nugget of silver or gold. To cope with this problem, we needed to shape raw commodities into pieces of a more predictable shape and weight; a trusted party could then stamp them with a mark to indicate the value and the quality of the coin.

At first, the task of standardizing coinage rested with private parties – but the responsibility was soon assumed by the State. The advantages of this transition seemed clear: a single, widely-accepted and easily-recognizable currency could be now used to settle virtually all private and official debts.

Alas, in what deserves the dubious distinction of being one of the earliest examples of monetary tomfoolery, some States succumbed to the temptation of fiddling with the coinage to accomplish anything from feeding the poor to waging wars. In particular, it would be common to stamp coins with the same face value but a progressively lower content of silver and gold. Perhaps surprisingly, the strategy worked remarkably well; at least in the times of peace, most people cared about the value stamped on the coin, not its precise composition or weight.

And so, over time, representative money was born: sooner or later, most States opted to mint coins from nearly-worthless metals, or print banknotes on paper and cloth. This radically new currency was accompanied with a simple pledge: the State offered to redeem it at any time for its nominal value in gold.

Of course, the promise was largely illusory: the State did not have enough gold to honor all the promises it had made. Still, as long as people had faith in their rulers and the redemption requests stayed low, the fundamental mechanics of this new representative currency remained roughly the same as before – and in some ways, were an improvement in that they lessened the insatiable demand for a rare commodity. Just as importantly, the new money still enabled international trade – using the underlying gold exchange rate as a reference point.

### 4. Fractional reserve banking and fiat money

For much of the recorded history, banking was an exceptionally dull affair, not much different from running a communal chicken
ledger of the old. But then, something truly marvelous happened in the 17th century: around that time, many European countries have witnessed
the emergence of fractional-reserve banks.

These private ventures operated according to a simple scheme: they accepted people’s coin
for safekeeping, promising to pay a premium on every deposit made. To meet these obligations and to make a profit, the banks then
used the pooled deposits to make high-interest loans to other folks. The financiers figured out that under normal circumstances
and when operating at a sufficient scale, they needed only a very modest reserve – well under 10% of all deposited money – to be
able to service the usual volume and size of withdrawals requested by their customers. The rest could be loaned out.

The very curious consequence of fractional-reserve banking was that it pulled new money out of thin air.
The funds were simultaneously accounted for in the statements shown to the depositor, evidently available for withdrawal or
transfer at any time; and given to third-party borrowers, who could spend them on just about anything. Heck, the borrowers could
deposit the proceeds in another bank, creating even more money along the way! Whatever they did, the sum of all funds in the monetary
system now appeared much higher than the value of all coins and banknotes issued by the government – let alone the amount of gold
sitting in any vault.

Of course, no new money was being created in any physical sense: all that banks were doing was engaging in a bit of creative accounting – the sort of which would probably land you in jail if you attempted it today in any other comparably vital field of enterprise. If too many depositors were to ask for their money back, or if too many loans were to go bad, the banking system would fold. Fortunes would evaporate in a puff of accounting smoke, and with the disappearance of vast quantities of quasi-fictitious (“broad”) money, the wealth of the entire nation would shrink.

In the early 20th century, the world kept witnessing just that; a series of bank runs and economic contractions forced the governments around the globe to act. At that stage, outlawing fractional-reserve banking was no longer politically or economically tenable; a simpler alternative was to let go of gold and move to fiat money – a currency implemented as an abstract social construct, with no predefined connection to the physical realm. A new breed of economists saw the role of the government not in trying to peg the value of money to an inflexible commodity, but in manipulating its supply to smooth out economic hiccups or to stimulate growth.

(Contrary to popular beliefs, such manipulation is usually not done by printing new banknotes; more sophisticated methods, such as lowering reserve requirements for bank deposits or enticing banks to invest its deposits into government-issued securities, are the preferred route.)

The obvious peril of fiat money is that in the long haul, its value is determined strictly by people’s willingness to accept a piece of paper in exchange for their trouble; that willingness, in turn, is conditioned solely on their belief that the same piece of paper would buy them something nice a week, a month, or a year from now. It follows that a simple crisis of confidence could make a currency nearly worthless overnight. A prolonged period of hyperinflation and subsequent austerity in Germany and Austria was one of the precipitating factors that led to World War II. In more recent times, dramatic episodes of hyperinflation plagued the fiat currencies of Israel (1984), Mexico (1988), Poland (1990), Yugoslavia (1994), Bulgaria (1996), Turkey (2002), Zimbabwe (2009), Venezuela (2016), and several other nations around the globe.

For the United States, the switch to fiat money came relatively late, in 1971. To stop the dollar from plunging like a rock, the Nixon administration employed a clever trick: they ordered the freeze of wages and prices for the 90 days that immediately followed the move. People went on about their lives and paid the usual for eggs or milk – and by the time the freeze ended, they were accustomed to the idea that the “new”, free-floating dollar is worth about the same as the old, gold-backed one. A robust economy and favorable geopolitics did the rest, and so far, the American adventure with fiat currency has been rather uneventful – perhaps except for the fact that the price of gold itself skyrocketed from $35 per troy ounce in 1971 to$850 in 1980 (or, from $210 to$2,500 in today’s dollars).

Well, one thing did change: now better positioned to freely tamper with the supply of money, the regulators in accord with the bankers adopted a policy of creating it at a rate that slightly outstripped the organic growth in economic activity. They did this to induce a small, steady degree of inflation, believing that doing so would discourage people from hoarding cash and force them to reinvest it for the betterment of the society. Some critics like to point out that such a policy functions as a “backdoor” tax on savings that happens to align with the regulators’ less noble interests; still, either way: in the US and most other developed nations, the purchasing power of any money kept under a mattress will drop at a rate of somewhere between 2 to 10% a year.

### 5. So what’s up with Bitcoin?

Well… countless tomes have been written about the nature and the optimal characteristics of government-issued fiat currencies. Some heterodox economists, notably including Murray Rothbard, have also explored the topic of privately-issued, decentralized, commodity-backed currencies. But Bitcoin is a wholly different animal.

In essence, BTC is a global, decentralized fiat currency: it has no (recoverable) intrinsic value, no central authority to issue it or define its exchange rate, and it has no anchoring to any historical reference point – a combination that until recently seemed nonsensical and escaped any serious scrutiny. It does the unthinkable by employing three clever tricks:

1. It allows anyone to create new coins, but only by solving brute-force computational challenges that get more difficult as the time goes by,

2. It prevents unauthorized transfer of coins by employing public key cryptography to sign off transactions, with only the authorized holder of a coin knowing the correct key,

3. It prevents double-spending by using a distributed public ledger (“blockchain”), recording the chain of custody for coins in a tamper-proof way.

The blockchain is often described as the most important feature of Bitcoin, but in some ways, its importance is overstated. The idea of a currency that does not rely on a centralized transaction clearinghouse is what helped propel the platform into the limelight – mostly because of its novelty and the perception that it is less vulnerable to government meddling (although the government is still free to track down, tax, fine, or arrest any participants). On the flip side, the everyday mechanics of BTC would not be fundamentally different if all the transactions had to go through Bitcoin Bank, LLC.

A more striking feature of the new currency is the incentive structure surrounding the creation of new coins. The underlying design democratized the creation of new coins early on: all you had to do is leave your computer running for a while to acquire a number of tokens. The tokens had no practical value, but obtaining them involved no substantial expense or risk. Just as importantly, because the difficulty of the puzzles would only increase over time, the hope was that if Bitcoin caught on, latecomers would find it easier to purchase BTC on a secondary market than mine their own – paying with a more established currency at a mutually beneficial exchange rate.

The persistent publicity surrounding Bitcoin and other cryptocurrencies did the rest – and today, with the growing scarcity of coins and the rapidly increasing demand, the price of a single token hovers somewhere south of $15,000. ### 6. So… is it bad money? Predicting is hard – especially the future. In some sense, a coin that represents a cryptographic proof of wasted CPU cycles is no better or worse than a currency that relies on cotton decorated with pictures of dead presidents. It is true that Bitcoin suffers from many implementation problems – long transaction processing times, high fees, frequent security breaches of major exchanges – but in principle, such problems can be overcome. That said, currencies live and die by the lasting willingness of others to accept them in exchange for services or goods – and in that sense, the jury is still out. The use of Bitcoin to settle bona fide purchases is negligible, both in absolute terms and in function of the overall volume of transactions. In fact, because of the technical challenges and limited practical utility, some companies that embraced the currency early on are now backing out. When the value of an asset is derived almost entirely from its appeal as an ever-appreciating investment vehicle, the situation has all the telltale signs of a speculative bubble. But that does not prove that the asset is destined to collapse, or that a collapse would be its end. Still, the built-in deflationary mechanism of Bitcoin – the increasing difficulty of producing new coins – is probably both a blessing and a curse. It’s going to go one way or the other; and when it’s all said and done, we’re going to celebrate the people who made the right guess. Because future is actually pretty darn easy to predict — in retrospect. # Weekly roundup: Truth or Dare Post Syndicated from Eevee original https://eev.ee/dev/2017/12/11/weekly-roundup-truth-or-dare/ Oops, I seem to have missed a week. I was doing Ludum Dare 40, but then I stopped, because— well hang on lemme just bullet this. • anise!!: I intended to enter Ludum Dare with glip; we were working on a game about Anise that we’d conceived about a month ago but never gotten around to. We made pretty decent progress, but realized we couldn’t fit anywhere near what we wanted into only three days, so we’re just… running with it. It’s going on a little longer than we wanted, but it’s getting pretty fun to play now, and I guess that’s pretty good progress given that we had absolutely nothing ten days ago. I’m even figuring out AI for once. • fox flux: Worked on some portraits and big text and underground tiles. Made some sound effects. Did a whole pretty cool footstep thing that combines particles with footstep noises and is very great. • other games: I discovered bitsy, the teeniest game engine I’ve ever seen, and wanted to make something with it — so I made Roguelike Simulator (and also wrote a release post). • cc: I got so frustrated with trying to find something in Unity Collab history that I cobbled together a thing for exporting Collab history to git. No, you can’t have it, I’m still not convinced it won’t delete my entire hard drive or something. Also I probably fixed a bug in the actual game somewhere in there. • blog: Finally finished that post about object models, only a month late! Hooray! Also wrote a game night post, which may or may not become a series? Also some other stuff that I’m not ready to share yet. I have a lot going on and can’t believe the month is a third over yet, but I’m charging forwards! # Game night 1: Lisa, Lisa, MOOP Post Syndicated from Eevee original https://eev.ee/blog/2017/12/05/game-night-1-lisa-lisa-moop/ For the last few weeks, glip (my partner) and I have spent a couple hours most nights playing indie games together. We started out intending to play a short list of games that had been recommended to glip, but this turns out to be a nice way to wind down, so we’ve been keeping it up and clicking on whatever looks interesting in the itch app. Most of the games are small and made by one or two people, so they tend to be pretty tightly scoped and focus on a few particular kinds of details. I’ve found myself having brain thoughts about all that, so I thought I’d write some of them down. I also know that some people (cough) tend not to play games they’ve never heard of, even if they want something new to play. If that’s you, feel free to play some of these, now that you’ve heard of them! Also, I’m still figuring the format out here, so let me know if this is interesting or if you hope I never do it again! First up: • Lisa: The Painful • Lisa: The Joyful • MOOP These are impressions, not reviews. I try to avoid major/ending spoilers, but big plot points do tend to leave impressions. ## Lisa: The Painful long · classic rpg · dec 2014 · lin/mac/win ·$10 on itch or steam · website

(cw: basically everything??)

Lisa: The Painful is true to its name. I hesitate to describe it as fun, exactly, but I’m glad we played it.

Everything about the game is dark. It’s a (somewhat loose) sequel to another game called Lisa, whose titular character ultimately commits suicide; her body hanging from a noose is the title screen for this game.

Ah, but don’t worry, it gets worse. This game takes place in a post-apocalyptic wasteland, where every female human — women, children, babies — is dead. You play as Brad (Lisa’s brother), who has discovered the lone exception: a baby girl he names Buddy and raises like a daughter. Now, Buddy has been kidnapped, and you have to go rescue her, presumably from being raped.

Ah, but don’t worry, it gets worse.

I’ve had a hard time putting my thoughts in order here, because so much of what stuck with me is the way the game entangles the plot with the mechanics.

I love that kind of thing, but it’s so hard to do well. I can’t really explain why, but I feel like most attempts to do it fall flat — they have a glimmer of an idea, but they don’t integrate it well enough, or they don’t run nearly as far as they could have. I often get the same feeling as, say, a hyped-up big moral choice that turns out to be picking “yes” or “no” from a menu. The idea is there, but the execution is so flimsy that it leaves no impact on me at all.

An obvious recent success here is Undertale, where the entire story is about violence and whether you choose to engage or avoid it (and whether you can do that). If you choose to eschew violence, not only does the game become more difficult, it arguably becomes a different game entirely. Granted, the contrast is lost if you (like me) tried to play as a pacifist from the very beginning. I do feel that you could go further with the idea than Undertale, but Undertale itself doesn’t feel incomplete.

Christ, I’m not even talking about the right game any more.

Okay, so: this game is a “classic” RPG, by which I mean, it was made with RPG Maker. (It’s kinda funny that RPG Maker was designed to emulate a very popular battle style, and now the only games that use that style are… made with RPG Maker.) The main loop, on the surface, is standard RPG fare: you walk around various places, talk to people, solve puzzles, recruit party members, and get into turn-based fights.

Now, Brad is addicted to a drug called Joy. He will regularly go into withdrawal, which manifests in the game as a status effect that cuts his stats (even his max HP!) dramatically.

It’s a really good use of games as a medium. Even before I’m invested in the characters, I’m invested in what’s happening to them, because it impacts the game!

Incidentally, you can get Joy as an item, which will temporarily cure your withdrawal… but you mostly find it by looting the corpses of grotesque mutant flesh horrors you encounter. I don’t think the game would have the player abruptly mutate out of nowhere, but I wasn’t about to find out, either. We never took any.

Virtually every staple of the RPG genre has been played with in some way to tie it into the theme/setting. I love it, and I think it works so well precisely because it plays with expectations of how RPGs usually work.

Most obviously, the game is a sidescroller, not top-down. You can’t jump freely, but you can hop onto one-tile-high boxes and climb ropes. You can also drop off off ledges… but your entire party will take fall damage, which gets rapidly more severe the further you fall.

This wouldn’t be too much of a problem, except that healing is hard to come by for most of the game. Several hub areas have campfires you can sleep next to to restore all your health and MP, but when you wake up, something will have happened to you. Maybe just a weird cutscene, or maybe one of your party members has decided to leave permanently.

Okay, so use healing items instead? Good luck; money is also hard to come by, and honestly so are shops, and many of the healing items are woefully underpowered.

Grind for money? Good luck there, too! While the game has plenty of battles, virtually every enemy is a unique overworld human who only appears once, and then is dead, because you killed him. Only a handful of places have unlimited random encounters, and grinding is not especially pleasant.

The “best” way to get a reliable heal is to savescum — save the game, sleep by the campfire, and reload if you don’t like what you wake up to.

In a similar vein, there’s a part of the game where you’re forced to play Russian Roulette. You choose a party member; he and an opponent will take turns shooting themselves in the head until someone finds a loaded chamber. If your party member loses, he is dead. And you have to keep playing until you win three times, so there’s no upper limit on how many people you might lose. I couldn’t find any way to influence who won, so I just had to savescum for a good half hour until I made it through with minimal losses.

It was maddening, but also a really good idea. Games don’t often incorporate the existence of saves into the gameplay, and when they do, they usually break the fourth wall and get all meta about it. Saves are never acknowledged in-universe here (aside from the existence of save points), but surely these parts of the game were designed knowing that the best way through them is by reloading. It’s rarely done, it can easily feel unfair, and it drove me up the wall — but it was certainly painful, as intended, and I kinda love that.

(Naturally, I’m told there’s a hard mode, where you can only use each save point once.)

The game also drives home the finality of death much better than most. It’s not hard to overlook the death of a redshirt, a character with a bit part who simply doesn’t appear any more. This game permanently kills your party members. Russian Roulette isn’t even the only way you can lose them! Multiple cutscenes force you to choose between losing a life or some other drastic consequence. (Even better, you can try to fight the person forcing this choice on you, and he will decimate you.) As the game progresses, you start to encounter enemies who can simply one-shot murder your party members.

It’s such a great angle. Just like with Brad’s withdrawal, you don’t want to avoid their deaths because it’d be emotional — there are dozens of party members you can recruit (though we only found a fraction of them), and most of them you only know a paragraph about — but because it would inconvenience you personally. Chances are, you have your strongest dudes in your party at any given time, so losing one of them sucks. And with few random encounters, you can’t just grind someone else up to an appropriate level; it feels like there’s a finite amount of XP in the game, and if someone high-level dies, you’ve lost all the XP that went into them.

The battles themselves are fairly straightforward. You can attack normally or use a special move that costs MP. SP? Some kind of points.

Two things in particular stand out. One I mentioned above: the vast majority of the encounters are one-time affairs against distinct named NPCs, who you then never see again, because they are dead, because you killed them.

The other is the somewhat unusual set of status effects. The staples like poison and sleep are here, but don’t show up all that often; more frequent are statuses like weird, drunk, stink, or cool. If you do take Joy (which also cures depression), you become joyed for a short time.

The game plays with these in a few neat ways, besides just Brad’s withdrawal. Some party members have a status like stink or cool permanently. Some battles are against people who don’t want to fight at all — and so they’ll spend most of the battle crying, purely for flavor impact. Seeing that for the first time hit me pretty hard; until then we’d only seen crying as a mechanical side effect of having sand kicked in one’s face.

The game does drag on a bit. I think we poured 10 in-game hours into it, which doesn’t count time spent reloading. It doesn’t help that you walk not super fast.

My biggest problem was with getting my bearings; I’m sure we spent a lot of that time wandering around accomplishing nothing. Most of the world is focused around one of a few hub areas, and once you’ve completed one hub, you can move onto the next one. That’s fine. Trouble is, you can go any of a dozen different directions from each hub, and most of those directions will lead you to very similar-looking hills built out of the same tiny handful of tiles. The connections between places are mostly cave entrances, which also largely look the same. Combine that with needing to backtrack for puzzle or progression reasons, and it’s incredibly difficult to keep track of where you’ve been, what you’ve done, and where you need to go next.

I don’t know that the game is wrong here; the aesthetic and world layout are fantastic at conveying a desolate wasteland. I wouldn’t even be surprised if the navigation were deliberately designed this way. (On the other hand, assuming every annoyance in a despair-ridden game is deliberate might be giving it too much credit.) But damn it’s still frustrating.

I felt a little lost in the battle system, too. Towards the end of the game, Brad in particular had over a dozen skills he could use, but I still couldn’t confidently tell you which were the strongest. New skills sometimes appear in the middle of the list or cost less than previous skills, and the game doesn’t outright tell you how much damage any of them do. I know this is the “classic RPG” style, and I don’t think it was hugely inconvenient, but it feels weird to barely know how my own skills work. I think this puts me off getting into new RPGs, just generally; there’s a whole new set of things I have to learn about, and games in this style often won’t just tell me anything, so there’s this whole separate meta-puzzle to figure out before I can play the actual game effectively.

Also, the sound could use a little bit of… mastering? Some music and sound effects are significantly louder and screechier than others. Painful, you could say.

The world is full of side characters with their own stuff going on, which is also something I love seeing in games; too often, the whole world feels like an obstacle course specifically designed for you.

Also, many of those characters are, well, not great people. Really, most of the game is kinda fucked up. Consider: the weird status effect is most commonly inflicted by the “Grope” skill. It makes you feel weird, you see. Oh, and the currency is porn magazines.

And then there are the gangs, the various spins on sex clubs, the forceful drug kingpins, and the overall violence that permeates everything (you stumble upon an alarming number of corpses). The game neither condones nor condemns any of this; it simply offers some ideas of how people might behave at the end of the world. It’s certainly the grittiest interpretation I’ve seen.

I don’t usually like post-apocalypses, because they try to have these very hopeful stories, but then at the end the world is still a blighted hellscape so what was the point of any of that? I like this game much better for being a blighted hellscape throughout. The story is worth following to see where it goes, not just because you expect everything wrapped up neatly at the end.

…I realize I’ve made this game sound monumentally depressing throughout, but it manages to pack in a lot of funny moments as well, from the subtle to the overt. In retrospect, it’s actually really good at balancing the mood so it doesn’t get too depressing. If nothing else, it’s hilarious to watch this gruff, solemn, battle-scarred, middle-aged man pedal around on a kid’s bike he found.

An obvious theme of the game is despair, but the more I think about it, the more I wonder if ambiguity is a theme as well. It certainly fits the confusing geography.

Even the premise is a little ambiguous. Is/was Olathe a city, a country, a whole planet? Did the apocalypse affect only Olathe, or the whole world? Does it matter in an RPG, where the only world that exists is the one mapped out within the game?

Towards the end of the game, you catch up with Buddy, but she rejects you, apparently resentful that you kept her hidden away for her entire life. Brad presses on anyway, insisting on protecting her.

At that point I wasn’t sure I was still on Brad’s side. But he’s not wrong, either. Is he? Maybe it depends on how old Buddy is — but the game never tells us. Her sprite is a bit smaller than the men’s, but it’s hard to gauge much from small exaggerated sprites, and she might just be shorter. In the beginning of the game, she was doing kid-like drawings, but we don’t know how much time passed after that. Everyone seems to take for granted that she’s capable of bearing children, and she talks like an adult. So is she old enough to be making this decision, or young enough for parent figure Brad to overrule her? What is the appropriate age of agency, anyway, when you’re the last girl/woman left more than a decade after the end of the world?

Can you repopulate a species with only one woman, anyway?

Well, that went on a bit longer than I intended. This game has a lot of small touches that stood out to me, and they all wove together very well.

Should you play it? I have absolutely no idea.

FINAL SCORE: 1 out of 6 chambers

## Lisa: The Joyful

fairly short · classic rpg · aug 2015 · lin/mac/win · \$5 on itch or steam

Surprise! There’s a third game to round out this trilogy.

Lisa: The Joyful is much shorter, maybe three hours long — enough to be played in a night rather than over the better part of a week.

This one picks up immediately after the end of Painful, with you now playing as Buddy. It takes a drastic turn early on: Buddy decides that, rather than hide from the world, she must conquer it. She sets out to murder all the big bosses and become queen.

The battle system has been inherited from the previous game, but battles are much more straightforward this time around. You can’t recruit any party members; for much of the game, it’s just you and a sword.

There is a catch! Of course.

The catch is that you do not have enough health to survive most boss battles without healing. With no party members, you cannot heal via skills. I don’t think you could buy healing items anywhere, either. You have a few when the game begins, but once you run out, that’s it.

Except… you also have… some Joy. Which restores you to full health and also makes you crit with every hit. And drops off of several enemies.

We didn’t even recognize Joy as a healing item at first, since we never used it in Painful; it’s description simply says that it makes you feel nothing, and we’d assumed the whole point of it was to stave off withdrawal, which Buddy doesn’t experience. Luckily, the game provided a hint in the form of an NPC who offers to switch on easy mode:

What’s that? Bad guys too tough? Not enough jerky? You don’t want to take Joy!? Say no more, you’ve come to the right place!

So the game is aware that it’s unfairly difficult, and it’s deliberately forcing you to take Joy, and it is in fact entirely constructed around this concept. I guess the title is a pretty good hint, too.

I don’t feel quite as strongly about Joyful as I do about Painful. (Admittedly, I was really tired and starting to doze off towards the end of Joyful.) Once you get that the gimmick is to force you to use Joy, the game basically reduces to a moderate-difficulty boss rush. Other than that, the only thing that stood out to me mechanically was that Buddy learns a skill where she lifts her shirt to inflict flustered as a status effect — kind of a lingering echo of how outrageous the previous game could be.

You do get a healthy serving of plot, which is nice and ties a few things together. I wouldn’t say it exactly wraps up the story, but it doesn’t feel like it’s missing anything either; it’s exactly as murky as you’d expect.

I think it’s worth playing Joyful if you’ve played Painful. It just didn’t have the same impact on me. It probably doesn’t help that I don’t like Buddy as a person. She seems cold, violent, and cruel. Appropriate for the world and a product of her environment, I suppose.

FINAL SCORE: 300 Mags

## MOOP

fairly short · inventory game · nov 2017 · win · free on itch

Finally, as something of a palate cleanser, we have MOOP: a delightful and charming little inventory game.

I don’t think “inventory game” is a real genre, but I mean the kind of game where you go around collecting items and using them in the right place. Puzzle-driven, but with “puzzles” that can largely be solved by simply trying everything everywhere. I’d put a lot of point and click adventures in the same category, despite having a radically different interface. Is that fair? Yes, because it’s my blog.

MOOP was almost certainly also made in RPG Maker, but it breaks the mold in a very different way by not being an RPG. There are no battles whatsoever, only interactions on the overworld; you progress solely via dialogue and puzzle-solving. Examining something gives you a short menu of verbs — use, talk, get — reminiscent of interactive fiction, or perhaps the graphical “adventure” games that took inspiration from interactive fiction. (God, “adventure game” is the worst phrase. Every game is an adventure! It doesn’t mean anything!)

Everything about the game is extremely chill. I love the monochrome aesthetic combined with a large screen resolution; it feels like I’m peeking into an alternate universe where the Game Boy got bigger but never gained color. I played halfway through the game before realizing that the protagonist (Moop) doesn’t have a walk animation; they simply slide around. Somehow, it works.

The puzzles are a little clever, yet low-pressure; the world is small enough that you can examine everything again if you get stuck, and there’s no way to lose or be set back. The music is lovely, too. It just feels good to wander around in a world that manages to make sepia look very pretty.

The story manages to pack a lot into a very short time. It’s… gosh, I don’t know. It has a very distinct texture to it that I’m not sure I’ve seen before. The plot weaves through several major events that each have very different moods, and it moves very quickly — but it’s well-written and doesn’t feel rushed or disjoint. It’s lighthearted, but takes itself seriously enough for me to get invested. It’s fucking witchcraft.

I think there was even a non-binary character! Just kinda nonchalantly in there. Awesome.

What a happy, charming game. Play if you would like to be happy and charmed.

FINAL SCORE: 1 waxing moon

# MagPi 64: get started with electronics

Post Syndicated from Rob Zwetsloot original https://www.raspberrypi.org/blog/magpi-64/

Hey folks, Rob here again! You get a double dose of me this month, as today marks the release of The MagPi 64. In this issue we give you a complete electronics starter guide to help you learn how to make circuits that connect to your Raspberry Pi!

MAGPI SIXTY-FOOUUUR!

## Wires, wires everywhere!

In the electronics feature, we’ll teach you how to identify different components in circuit diagrams, we’ll explain what they do, and we’ll give you some basic wiring instructions so you can take your first steps. The feature also includes step-by-step tutorials on how to make a digital radio and a range-finder, meaning you can test out your new electronics skills immediately!

## Christmas tutorials

Electronics are cool, but what else is in this issue? Well, we have exciting news about the next Google AIY Projects Vision kit, which forgoes audio for images, allowing you to build a smart camera with your Raspberry Pi.

We’ve also included guides on how to create your own text-based adventure game and a kaleidoscope camera. And, just in time for the festive season, there’s a tutorial for making a 3D-printed Pi-powered Christmas tree star. All this in The MagPi 64, along with project showcases, reviews, and much more!

#### Kaleido Cam

Using a normal web cam or the Raspberry Pi camera produce real time live kaleidoscope effects with the Raspberry Pi. This video shows the normal mode, along with an auto pre-rotate, and a horizontal and vertical flip.

## Get The MagPi 64

Issue 64 is available today from WHSmith, Tesco, Sainsbury’s, and Asda. If you live in the US, head over to your local Barnes & Noble or Micro Center in the next few days. You can also get the new issue online from our store, or digitally via our Android and iOS apps. And don’t forget, there’s always the free PDF as well.

Want to support the Raspberry Pi Foundation and the magazine, and get some cool free stuff? If you take out a twelve-month print subscription to The MagPi, you’ll get a Pi Zero W, Pi Zero case, and adapter cables absolutely free! This offer does not currently have an end date.

We hope you enjoy this issue!

#### Nintendo Sixty-FOOOOOOOOOOUR

Brandon gets an n64 for christmas 1998 and gets way too excited inquiries about usage / questions / comments? [email protected] © n64kids.com

The post MagPi 64: get started with electronics appeared first on Raspberry Pi.

# Weekly roundup: VK Ultra

Post Syndicated from Eevee original https://eev.ee/dev/2017/11/27/weekly-roundup-vk-ultra/

• fox flux: Cleaned up and committed the “heart get” overlay and worked on some more art for it. Diagnosed a very obscure physics problem, but didn’t come up with a good solution yet; physics is hard! Drew a very good tree trunk to use as a spawn point; also worked on some background foliage, though less successfully. Played with colors a bit. Tried to work out a tileset for underground areas.

• music: I wrote like half of a little chiptune song that I actually like so far! I’m now seriously toying with the idea of doing my own music for fox flux. Played a bit with more sound effects, too.

• blog: I wrote up the Eevee mugshot set for Doom I made, as an inaugural post for the release category.

• veekun: Finished up Ultra Sun and Ultra Moon! Pokémon sprites, box sprites, item sprites, and the same data as Sun/Moon. I say “finished” but of course plenty of stuff is still missing, alas.

• cc: I’m trying to make glip some building blocks so that they can actually start building the game, so I made some breakable blocks. Also wrote a little shader for implementing their parallax background, which involves a bunch of layer modes.

• misc: I got a new keyboard. Also I installed umatrix because noscript’s web extension version is half-broken and driving me up the wall. Sorry, noscript.

Huh, that’s not a bad haul, despite a few nights of incredibly bad sleep. Cool.

# Presenting Amazon Sumerian: An easy way to create VR, AR, and 3D experiences

Post Syndicated from Tara Walker original https://aws.amazon.com/blogs/aws/launch-presenting-amazon-sumerian/

If you have had an opportunity to read any of my blog posts or attended any session I’ve conducted at various conferences, you are probably aware that I am definitively a geek girl. I am absolutely enamored with all of the latest advancements that have been made in technology areas like cloud, artificial intelligence, internet of things and the maker space, as well as, with virtual reality and augmented reality. In my opinion, it is a wonderful time to be a geek. All the things that we dreamed about building while we sweated through our algorithms and discrete mathematics classes or the technology we marveled at when watching Star Wars and Star Trek are now coming to fruition.  So hopefully this means it will only be a matter of time before I can hyperdrive to other galaxies in space, but until then I can at least build the 3D virtual reality and augmented reality characters and images like those featured in some of my favorite shows.

Amazon Sumerian provides tools and resources that allows anyone to create and run augmented reality (AR), virtual reality (VR), and 3D applications with ease.  With Sumerian, you can build multi-platform experiences that run on hardware like the Oculus, HTC Vive, and iOS devices using WebVR compatible browsers and with support for ARCore on Android devices coming soon.

This exciting new service, currently in preview, delivers features to allow you to design highly immersive and interactive 3D experiences from your browser. Some of these features are:

• Editor: A web-based editor for constructing 3D scenes, importing assets, scripting interactions and special effects, with cross-platform publishing.
• Object Library: a library of pre-built objects and templates.
• Asset Import: Upload 3D assets to use in your scene. Sumerian supports importing FBX, OBJ, and coming soon Unity projects.
• Scripting Library: provides a JavaScript scripting library via its 3D engine for advanced scripting capabilities.
• Hosts: animated, lifelike 3D characters that can be customized for gender, voice, and language.
• AWS Services Integration: baked in integration with Amazon Polly and Amazon Lex to add speech and natural language to into Sumerian hosts. Additionally, the scripting library can be used with AWS Lambda allowing use of the full range of AWS services.

Since Amazon Sumerian doesn’t require you to have 3D graphics or programming experience to build rich, interactive VR and AR scenes, let’s take a quick run to the Sumerian Dashboard and check it out.

From the Sumerian Dashboard, I can easily create a new scene with a push of a button.

A default view of the new scene opens and is displayed in the Sumerian Editor. With the Tara Blog Scene opened in the editor, I can easily import assets into my scene.

I’ll click the Import Asset button and pick an asset, View Room, to import into the scene. With the desired asset selected, I’ll click the Add button to import it.

Excellent, my asset was successfully imported into the Sumerian Editor and is shown in the Asset panel.  Now, I have the option to add the View Room object into my scene by selecting it in the Asset panel and then dragging it onto the editor’s canvas.

I’ll repeat the import asset process and this time I will add the Mannequin asset to the scene.

Additionally, with Sumerian, I can add scripting to Entity assets to make my scene even more exciting by adding a ScriptComponent to an entity and creating a script.  I can use the provided built-in scripts or create my own custom scripts. If I create a new custom script, I will get a blank script with some base JavaScript code that looks similar to the code below.

'use strict';
/* global sumerian */
//This is Me-- trying out the custom scripts - Tara

var setup = function (args, ctx) {
// Called when play mode starts.
};
var fixedUpdate = function (args, ctx) {
// Called on every physics update, after setup().
};
var update = function (args, ctx) {
// Called on every render frame, after setup().
};
var lateUpdate = function (args, ctx) {
// Called after all script "update" methods in the scene has been called.
};
var cleanup = function (args, ctx) {
// Called when play mode stops.
};
var parameters = [];

Very cool, I just created a 3D scene using Amazon Sumerian in a matter of minutes and I have only scratched the surface.

Summary

The Amazon Sumerian service enables you to create, build, and run virtual reality (VR), augmented reality (AR), and 3D applications with ease.  You don’t need any 3D graphics or specialized programming knowledge to get started building scenes and immersive experiences.  You can import FBX, OBJ, and Unity projects in Sumerian, as well as upload your own 3D assets for use in your scene. In addition, you can create digital characters to narrate your scene and with these digital assets, you have choices for the character’s appearance, speech and behavior.

You can learn more about Amazon Sumerian and sign up for the preview to get started with the new service on the product page.  I can’t wait to see what rich experiences you all will build.

Tara

# Eevee mugshot set for Doom

Post Syndicated from Eevee original https://eev.ee/release/2017/11/23/eevee-mugshot-set-for-doom/

A full replacement of Doomguy’s vast array of 42 expressions.

You can get it yourself if you want to play Doom as me, for some reason? It does nothing but replace a few sprites, so it works with any Doom flavor (including vanilla) on 1, 2, or Final. Just run Doom with -file eeveemug.wad. With GZDoom, you can load it automatically.

I don’t entirely know why I did this. I drew the first one on a whim, then realized there was nothing really stopping me from making a full set, so I spent a day doing that.

The funny thing is that I usually play Doom with ZDoom’s “alternate” HUD. It’s a full-screen overlay rather than a huge bar, and — crucially — it does not show the mugshot. It can’t even be configured to show the mugshot. As far as I’m aware, it can’t even be modded to show the mugshot. So I have to play with the OG status bar if I want to actually use the thing I made.

I’m pretty happy with the results overall! I think I did a decent job emulating the Doom “surreal grit” style. I did the shading with Aseprite‘s shading mode — instead of laying down a solid color, it shifts pixels along a ramp of colors you select every time you draw over them. Doom’s palette has a lot of browns, so I made a ramp out of all of them and kept going over furry areas, nudging pixels into being lighter or darker, until I liked the texture. It was a lot like making a texture in a sketch with a lot of scratchy pencil strokes.

I also gleaned some interesting things about smoothness and how the eye interprets contours? I tried to explain this on Twitter and had a hell of a time putting it into words, but the short version is that it’s amazing to see the difference a single misplaced pixel can make, especially as you slide that pixel between dark and light.

Speaking of which, Doom’s palette is incredibly weird to work with. Thank goodness Eevees are brown! The game does have to draw arbitrary levels of darkness all with the same palette, which partly explains the number of dark colors and gradients — but I believe a number of the colors are exact duplicates, so close they might as well be duplicates, or completely unused in stock Doom assets. I guess they had no reason to optimize for people trying to add arbitrary art to the game 25 years later, though. (And nowadays, GZDoom includes a truecolor software renderer, so the palette is becoming less and less important.)

I originally wanted the god mode sprite to be a Sylveon, but Sylveon is made of pink and azure and blurple, and I don’t think I could’ve pulled it off with this set of colors. I even struggled with the color of the mane a bit — I usually color it with pretty pale colors, but Doom only has a couple of those, and they’re very saturated. I ended up using a lot more dark yellows than I would normally, and thankfully it worked out pretty well.

The most significant change I made between the original sprite and the final set was the eye color:

(This is STFST20, a frame from the default three-frame “glacing around” animation that plays when the player has between 40 and 59 health. Doom Wiki has a whole article on the mugshot if you’re interested.)

The blue eyes in my original just do not work at all. The Doom palette doesn’t have a lot of subtle colors, and its blues in particular are incredibly bad. In the end, I made the eyes basically black, though with a couple pixels of very dark blue in them.

After I decided to make the full set, I started by making a neutral and completely healthy front pose, then derived the others from that (with a very complicated system of layers). You can see some of the side effects of that here: the face doesn’t actually turn when glancing around, because hoo boy that would’ve been a lot of work, and so the cheek fluff is visible on both sides.

I also notice that there are two columns of identical pixels in each eye! I fixed that in the glance to the right, but must’ve forgotten about it here. Oh, well; I didn’t even notice until I zoomed in just now.

The original sprites might not be quite aligned correctly in the above image. The available space in the status bar is 35×31, of which a couple pixels go to an inset border, leaving 33×30. I drew all of my sprites at that size, but the originals are all cropped and have varying offsets (part of the Doom sprite format). I extremely can’t be assed to check all of those offsets for over a dozen sprites, so I just told ImageMagick to center them. (I only notice right now that some of the original sprites are even a full 31 pixels tall and draw over the top border that I was so careful to stay out of!)

Anyway, this is a representative sample of the Doom mugshot poses.

The top row shows all eight frames at full health. The first three are the “idle” state, drawn when nothing else is going on; the sprite usually faces forwards, but glances around every so often at random. The forward-facing sprite is the one I finalized first.

I tried to take a lot of cues from the original sprite, seeing as I wanted to match the style. I’d never tried drawing a sprite with a large palette and a small resolution before, and the first thing that struck me was Doomguy’s lips — the upper lip, lips themselves, and shadow under the lower lip are all created with only one row of pixels each. I thought that was amazing. Now I even kinda wish I’d exaggerated that effect a bit more, but I was wary of going too dark when there’s a shadow only a couple pixels away. I suppose Doomguy has the advantage of having, ah, a chin.

I did much the same for the eyebrows, which was especially necessary because Doomguy has more of a forehead than my Eevee does. I probably could’ve exaggerated those a bit more, as well! Still, I love how they came out — especially in the simple looking-around frames, where even a two-pixel eyebrow raise is almost comically smug.

The fourth frame is a wild-ass grin (even named STFEVL0), which shows for a short time after picking up a new weapon. Come to think of it, that’s a pretty rare occurrence when playing straight through one of the Doom games; you keep your weapons between levels.

The fifth through seventh are also a set. If the player takes damage, the status bar will briefly show one of these frames to indicate where the damage is coming from. You may notice that where Doomguy bravely faces the source of the pain, I drew myself wincing and recoiling away from it.

The middle frame of that set also appears while the player is firing continuously (regardless of damage), so I couldn’t really make it match the left and right ones. I like the result anyway. It was also great fun figuring out the expressions with the mouth — that’s another place where individual pixels make a huge difference.

Finally, the eighth column is the legendary “ouch” face, which appears when the player takes more than 20 damage at once. It may look completely alien to you, because vanilla Doom has a bug that only shows this face when the player gains 20 or more health while taking damage. This is vanishingly rare (though possible!), so the frame virtually never appears in vanilla Doom. Lots of source ports have fixed this bug, making the ouch face it a bit better known, but I usually play without the mugshot visible so it still looks super weird to me. I think my own spin on it is a bit less, ah, body horror?

The second row shows deterioration. It is pretty weird drawing yourself getting beaten up.

A lot of Doomguy’s deterioration is in the form of blood dripping from under his hair, which I didn’t think would translate terribly well to a character without hair. Instead, I went a little cartoony with it, adding bandages here and there. I had a little bit of a hard time with the bloodshot eyes at this resolution, which I realize as I type it is a very poor excuse when I had eyes three times bigger than Doomguy’s. I do love the drooping ears, with the possible exception of the fifth state, which I’m not sure is how that would actually look…? Oh well. I also like the bow becoming gradually unravelled, eventually falling off entirely when you die.

Oh, yes, the sixth frame there (before the gap) is actually for a dead player. Doomguy’s bleeding becomes markedly more extreme here, but again that didn’t really work for me, so I went a little sillier with it. A little. It’s still pretty weird drawing yourself dead.

That leaves only god mode, which is incredible. I love that glow. I love the faux whisker shapes it makes. I love how it fades into the background. I love that 100% pure “oh this is pretty good” smile. It all makes me want to just play Doom in god mode forever.

Now that I’ve looked closely at these sprites again, I spy a good half dozen little inconsistencies and nitpicks, which I’m going to refrain from spelling out. I did do this in only a day, and I think it came out pretty dang well considering.

Maybe I’ll try something else like this in the future. Not quite sure what, though; there aren’t many small and self-contained sets of sprites like this in Doom. Monsters are several times bigger and have a zillion different angles. Maybe some pickups, which only have one frame?

Hmm. Parting thought: I’m not quite sure where I should host this sort of one-off thing. It arguably belongs on Itch, but seems really out of place alongside entire released games. It also arguably belongs on the idgames archive, but I’m hesitant to put it there because it’s such an obscure thing of little interest to a general audience. At the moment it’s just a file I’ve uploaded to wherever on my own space, but I now have three little Doom experiments with no real permanent home.

# Use the New Visual Editor to Create and Modify Your AWS IAM Policies

Today, AWS Identity and Access Management (IAM) made it easier for you to create and modify your IAM policies by using a point-and-click visual editor in the IAM console. The new visual editor guides you through granting permissions for IAM policies without requiring you to write policies in JSON (although you can still author and edit policies in JSON, if you prefer). This update to the IAM console makes it easier to grant least privilege for the AWS service actions you select by listing all the supported resource types and request conditions you can specify. Policy summaries identify unrecognized services and actions and permissions errors when you import existing policies, and now you can use the visual editor to correct them. In this blog post, I give a brief overview of policy concepts and show you how to create a new policy by using the visual editor.

### IAM policy concepts

You use IAM policies to define permissions for your IAM entities (groups, users, and roles). Policies are composed of one or more statements that include the following elements:

• Effect: Determines if a policy statement allows or explicitly denies access.
• Action: Defines AWS service actions in a policy (these typically map to individual AWS APIs.)
• Resource: Defines the AWS resources to which actions can apply. The defined resources must be supported by the actions defined in the Action element for permissions to be granted.
• Condition: Defines when a permission is allowed or denied. The conditions defined in a policy must be supported by the actions defined in the Action element for the permission to be granted.

To grant permissions, you attach policies to groups, users, or roles. Now that I have reviewed the elements of a policy, I will demonstrate how to create an IAM policy with the visual editor.

### How to create an IAM policy with the visual editor

Let’s say my human resources (HR) recruiter, Casey, needs to review files located in an Amazon S3 bucket for all the product manager (PM) candidates our HR team has interviewed in 2017. To grant this access, I will create and attach a policy to Casey that grants list and limited read access to all folders that begin with PM_Candidate in the pmrecruiting2017 S3 bucket. To create this new policy, I navigate to the Policies page in the IAM console and choose Create policy. Note that I could also use the visual editor to modify existing policies by choosing Import existing policy; however, for Casey, I will create a new policy.

On the Visual editor tab, I see a section that includes Service, Actions, Resources, and Request Conditions.

### Select a service

To grant S3 permissions, I choose Select a service, type S3 in the search box, and choose S3 from the list.

### Select actions

After selecting S3, I can define actions for Casey by using one of four options:

1. Filter actions in the service by using the search box.
2. Type actions by choosing Add action next to Manual actions. For example, I can type List* to grant all S3 actions that begin with List*.
3. Choose access levels from List, Read, Write, Permissions management, and Tagging.
4. Select individual actions by expanding each access level.

In the following screenshot, I choose options 3 and 4, and choose List and s3:GetObject from the Read access level.

We introduced access levels when we launched policy summaries earlier in 2017. Access levels give you a way to categorize actions and help you understand the permissions in a policy. The following table gives you a quick overview of access levels.

 Access level Description Example actions List Actions that allow you to see a list of resources s3:ListBucket, s3:ListAllMyBuckets Read Actions that allow you to read the content in resources s3:GetObject, s3:GetBucketTagging Write Actions that allow you to create, delete, or modify resources s3:PutObject, s3:DeleteBucket Permissions management Actions that allow you to grant or modify permissions to resources s3:PutBucketPolicy Tagging Actions that allow you to create, delete, or modify tags Note: Some services support authorization based on tags. s3:PutBucketTagging, s3:DeleteObjectVersionTagging

Note: By default, all actions you choose will be allowed. To deny actions, choose Switch to deny permissions in the upper right corner of the Actions section.

As shown in the preceding screenshot, if I choose the question mark icon next to GetObject, I can see the description and supported resources and conditions for this action, which can help me scope permissions.

The visual editor makes it easy to decide which actions I should select by providing in an integrated documentation panel the action description, supported resources or conditions, and any required actions for every AWS service action. Some AWS service actions have required actions, which are other AWS service actions that need to be granted in a policy for an action to run. For example, the AWS Directory Service action, ds:CreateDirectory, requires seven Amazon EC2 actions to be able to create a Directory Service directory.

### Choose resources

In the Resources section, I can choose the resources on which actions can be taken. I choose Resources and see two ways that I can define or select resources:

1. Define specific resources
2. Select all resources

Specific is the default option, and only the applicable resources are presented based on the service and actions I chose previously. Because I want to grant Casey access to some objects in a specific bucket, I choose Specific and choose Add ARN under bucket.

In the pop-up, I type the bucket name, pmrecruiting2017, and choose Add to specify the S3 bucket resource.

To specify the objects, I choose Add ARN under object and grant Casey access to all objects starting with PM_Candidate in the pmrecruiting2017 bucket. The visual editor helps you build your Amazon Resource Name (ARN) and validates that it is structured correctly. For AWS services that are AWS Region specific, the visual editor prompts for AWS Region and account number.

The visual editor displays all applicable resources in the Resources section based on the actions I choose. For Casey, I defined an S3 bucket and object in the Resources section. In this example, when the visual editor creates the policy, it creates three statements. The first statement includes all actions that require a wildcard (*) for the Resource element because this action does not support resource-level permissions. The second statement includes all S3 actions that support an S3 bucket. The third statement includes all actions that support an S3 object resource. The visual editor generates policy syntax for you based on supported permissions in AWS services.

### Specify request conditions

For additional security, I specify a condition to restrict access to the S3 bucket from inside our internal network. To do this, I choose Specify request conditions in the Request Conditions section, and choose the Source IP check box. A condition is composed of a condition key, an operator, and a value. I choose aws:SourceIp for my Key so that I can control from where the S3 files can be accessed. By default, IpAddress is the Operator, and I set the Value to my internal network.

To add other conditions, choose Add condition and choose Save changes after choosing the key, operator, and value.

After specifying my request condition, I am now able to review all the elements of these S3 permissions.

Next, I can choose to grant permissions for another service by choosing Add new permissions (bottom left of preceding screenshot), or I can review and create this new policy. Because I have granted all the permissions Casey needs, I choose Review policy. I type a name and a description, and I review the policy summary before choosing Create policy.

Now that I have created the policy, I attach it to Casey by choosing the Attached entities tab of the policy I just created. I choose Attach and choose Casey. I then choose Attach policy. Casey should now be able to access the interview files she needs to review.

### Summary

The visual editor makes it easier to create and modify your IAM policies by guiding you through each element of the policy. The visual editor helps you define resources and request conditions so that you can grant least privilege and generate policies. To start using the visual editor, sign in to the IAM console, navigate to the Policies page, and choose Create policy.

If you have comments about this post, submit them in the “Comments” section below. If you have questions about or suggestions for this solution, start a new thread on the IAM forum.

– Joy