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evanofsky

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  1. The Poor Man's 3D Camera

    Each of us have our own giants to face. This is a story about one of my giants. Something I never imagined could make a grown man cry, until it did. A 3D camera. No one can face your giants for you. This is a story, not a walkthrough. Expect no useful information. For that I recommend 50 Game Camera Mistakes by thatgamecompany's John Nesky. His job title is literally "camera designer". The story starts in 2014 with a seemingly harmless seven-day game jam. 7DFPS 2014 Exhausted from crunching on my first game, I decide it would be good to take a break and make a first-person shooter for 7DFPS. This is a terrible decision. The idea is simple: an FPS where you are the bullet. Click to jump from wall to wall. If someone's head happens to be between you and the next wall, sucks for them. The main problem is that, when you shoot to a new surface, the game necessarily buries your face directly into that surface, filling the whole screen with a solid blue color. You can see my first solution above. After landing, the game "reflects" your direction off the surface you landed on, and tweens the camera to face the new direction. So when you shoot into a wall head-on, the camera does a complete 180. Of course, I can't place the camera directly on the surface, or there would be clipping artifacts. So I space the camera a bit out from the wall, which leads to another problem: Here the extra space between the camera and the surface allows you to aim at any location on the surface and launch there. In theory, your "character" is actually flush with the surface, which should make this physically impossible. I throw a band-aid on this problem by clamping the camera so that it can't aim at or behind the surface it's attached to. I end up working 96 hours in a week to finish this masterpiece that will surely take the world by storm. Two YouTubers play it for a grand total of 10,000 views. Like every good vacation, the experience leaves me exhausted and depressed on Monday morning. Over the next 8 months, I finish my other game, take an actual vacation, then, instead of throwing away the Unity prototype like any sane person would, I start rebuilding it in a brand new custom C++ engine. The new game is an expansion of the prototype, which means more features, more gameplay, more pain and suffering! One of the first new features is the ability to crawl along walls, floors, and ceilings: A couple months later, camera problems start to manifest. As players crawl around different surfaces, I have to forcefully nudge the camera to keep it from staring straight into a wall. I use spherical linear interpolation (slerp) to smooth out the transition between angled surfaces, but it's still not great. In the gif below, the player on the right does not manually move their camera at all; the wall forces them to look up automatically. At this point, everything is completely unreadable and confusing. The first-person view prevents players from seeing their character, and they often take several minutes to realize they're playing as a creepy crawly spider bot. Once they finally get it, they can't figure out why the camera keeps getting forced around, and why they can't aim at the surface they're attached to. I slap on another band-aid in the form of a shader that blacks out everything "behind" you, everything that's physically impossible to reach. I also have it darken out of range areas. Now the game is not only unreadable and confusing, but also ugly! By sheer chance, I happen to turn on a debug flag that moves the camera back from the player two units. Literally the poor man's third-person camera. And behold, it was not the worst thing in the world. I finally realize I'm making a third-person game, and so set about implementing it for real. The Culling Saga One of the deadliest scourges of humanity, right after Facebook and taxes, is a third-person camera that constantly zooms and bumps around to avoid in-game geometry. Rather than move the camera, I decide to just cull anything that blocks the camera's view. Half of the job is done right out the gate because my game engine, like most engines, automatically culls triangles that face away from the camera (also known as "back-faces"). I write a shader to handle the rest. It culls everything within a certain distance of the camera. What's that you say? My screenshots look weird with spider bots floating in empty space because the wall got culled? It'll be fine. It's fine. Don't worry about it. What, what now? You can catch glimpses of stuff you're not supposed to see, including the skybox? Look, I'm sure it's just a minor thing. Okay. That's pretty bad. What if instead of carving spheres around the player and camera, I use a cylinder instead? And what if I actually render a solid black cylinder whenever the camera is inside a wall? So close, yet so far. The cylinder blocks out most of the ugly geometry it needs to, but sometimes you can still see through things. I could extend the cylinder to block more, but I would have to clip it so it stays inside the level geometry. Even now, the cylinder sometimes blocks too much, because I only clip it against the player's current wall. Here I only want the cylinder to block the ugly insides of the ledge. Instead it blocks everything behind the player. I would have to query all the geometry surrounding the player and clip the cylinder against all those planes. And that's assuming I can figure out what's "inside" and "outside" the level geometry, which is not air-tight. There are overlapping faces, shapes that clip into each other, and plenty of other lazy hacks— I mean, clever tricks. What if I just turn off back-face culling? Use the same culling shader, and instead of the cylinder, rely on the back-faces to block anything you're not supposed to see. This works perfectly in some cases: Other times it does a great job of showing off my lazy hacks, like this ramp that simply extends into the floor rather than meeting it cleanly: It doesn't help that the back-faces still receive accurate lighting. Feels like the level is a hollow shell. Fine. I'll spend a couple weeks welding level geometry together, and I'll render the back-faces in solid black. How about now? Getting less terrible all the time. With a little depth buffer bias, a special tag in the G-buffer for back-faces, and a few extra texture taps in the composite shader, I can filter out those pesky lines too: The gifs above also show off the new culling shape. Instead of a cylinder, which indiscriminately carves out an uncouth shape much larger than necessary: I switch to a cone, to ensure I only cull things what need culling. But the cone has problems too. It's possible for the player to back up so close to a wall that the cone intersects the wall in an incredibly narrow circle, leaving a tiny hole for the player to peer through. From somewhere deep inside my repressed memories of Calc II springs an exotic mathematical creature known as a paraboloid: A quick trip to the grimoire to remind myself of the formula, a few incantations in a darkened room with a mirror, and the creature is summoned into GLSL form. The culled circle still tapers a little, but it's enough to see fairly well. Good enough for government work. Ship it! UX UX is, like, super important. Take it from me, a full-stack growth-hacking happiness engineer co-founder. Let me tell you about Our Incredible Journey. At first, the game had a terrible retention rate. I did some A/B testing, streamlined the user onboarding, pivoted to clickbait, bought some fraudulent traffic, and now I'm at $10k MRR. I'm also taking cold showers every morning and learning Farsi on Duolingo. If you can keep your eyes from rolling back completely and irreparably inside your head, "User Experience" is a decent descriptor for the interactive aspects of game development, the other contender being "Game Feel". It's the thing you can only get by interacting with the software yourself. It's the thing that makes you smile with surprise when you pick up the controller for the first time, even though you've spent the last hour watching someone else play. It's also basically impossible for me to get right on the first ten tries. Here's an example of my terrible camera UX. When you hit an enemy player without killing them, you bounce off. The camera instantly snaps around to follow your new trajectory. Of course I slerp the rotation a little, but still, you can barely see it happen. I have no reason to lock the camera like this, it's just a carry-over from when the game was first-person, when it made sense to always point the camera where the player was headed next. It takes someone at a convention telling me what an idiot I am to make me finally unlock the camera. A one-line change that takes a whole year. Later, someone on Twitch yells out a self-evidently brilliant suggestion: let the camera lag behind the player a little when they launch. This also takes only a handful of lines to test out, although the numbers don't feel good until a week or two of tweaking. So many of my design decisions are simply carried over from old and outdated assumptions, even though they stopped making sense several versions ago. Here's an example. Remember how I clamp the camera rotation to keep the player from aiming at the surface they're currently attached to? Turns out this gets old after a while, especially in third-person. People want freedom, they don't want you shoving their camera around. I grudgingly loosen the shackles a bit by clamping the rotation against a cone instead of a plane. I use spherical interpolation again to smoothly swing the cone around and nudge the camera away from the wall. Unfortunately, slerp doesn't always rotate the way you want it to. Sometimes the cone pushes the camera in a completely different direction as it rotates to match the surface. Instead of rotating the cone, I decide to instantly snap it to the surface, but scale it up slowly. So it starts as a thin sliver and slowly expands into a fat cone, pushing the camera out as it grows. Everything's going just swimmingly until Momin Khan asks me... is it even necessary to clamp the camera any more? It made sense when the game was first-person, but that was two years ago. I immediately get defensive. How else can I keep the camera from staring straight at the wall for 90% of the game? But I slowly realize he's right. I compromise in the end. I nudge the camera for a split second after landing, then shrink the cone back down to zero to allow glorious unfettered camera freedom. Full range of motion, baybee Now that the player can aim at their currently attached surface, what happens when they try to launch there? I eventually solve this problem by allowing spider bots to "dash" along the surface. I have no physical explanation for how they do it. It's a video game. There's another problem, however. Normally, the game does a raycast starting at the third-person camera and continuing straight through the reticle. When the spider bot launches, it compensates and launches where the player wants it to go, like this: However, sometimes the camera can see and aim at a point the spider bot can't reach. I solve this by ruling everything behind the player's current surface "out of bounds". I even have a shader to darken the forbidden areas. Look, Simba. Everything the light touches is our kingdom. This is really frustrating and confusing to people. Finally Nathan Fouts from Mommy's Best Games tells me to just cheat and let the player go there even if it doesn't make physical sense. I don't like the idea of breaking my game physics so I compromise by having the spider bot dash to the edge and then fly the rest of the way. It all happens so fast, you don't even notice it. Here it is in slow motion: Conclusion Some tasks cannot be sped up. If I had put "make 3D camera" on a Gantt chart, I would have stopped 10% of the way through this article and called it good. The point is, most of these ideas are simple and obvious in hindsight, but I had to make a lot of mistakes to find them. It's nearly impossible to coalesce good design decisions straight from the ether. The only reliable method is iteration and trial and error. Thanks for reading. What embarrassingly obvious design improvements have you been slapped in the face with? Deceiver is set to launch on Kickstarter in early February 2018. Join the mail list to be notified of its release, or check out the source code on GitHub.
  2. Thirteen Years of Bad Game Code

    I think we're in agreement; we just have different definitions of what a singleton is. To me, a singleton is defined as a function that lazily initializes a single global instance of an object. Without that lazy check, it's just... a regular global. I am totally cool with grouping global variables into a structure or object to "logically split them out and divy up code and responsibilities". I do it all the time. I only take issue when you put a singleton in front of it.
  3. Thirteen Years of Bad Game Code

    Alone on a Friday night, in need of some inspiration, you decide to relive some of your past programming conquests. The old archive hard drive slowly spins up, and the source code of the glory days scrolls by... Oh no. This is not at all what you expected. Were things really this bad? Why did no one tell you? Why were you like this? Is it even possible to have that many gotos in a single function? You quickly close the project. For a brief second, you consider deleting it and scrubbing the hard drive. What follows is a compilation of lessons, snippets, and words of warning salvaged from my own excursion into the past. Names have not been changed, to expose the guilty. 2004 I was thirteen. The project was called Red Moon -- a wildly ambitious third-person jet combat game. The few bits of code that were not copied verbatim out of Developing Games in Java were patently atrocious. Let's look at an example. I wanted to give the player multiple weapons to switch between. The plan was to rotate the weapon model down inside the player model, swap it out for the next weapon, then rotate it back. Here's the animation code. Don't think about it too hard.public void updateAnimation(long eTime) { if(group.getGroup("gun") == null) { group.addGroup((PolygonGroup)gun.clone()); } changeTime -= eTime; if(changing && changeTime = 0; i = Math.Min(this.bindings.Count - 1, i - 1)) this.bindings.OnChanged(this); } }} Every single field in the game, down to the last boolean, had an unwieldy dynamically allocated array attached to it. Take a look at the loop that notifies the bindings of a property change to get an idea of the issues I ran into with this paradigm. It has to iterate through the binding list backward, since a binding could actually add or delete UI elements, causing the binding list to change. Still, I loved data binding so much that I built the entire game on top of it. I broke down objects into components and bound their properties together. Things quickly got out of hand.jump.Add(new Binding(jump.Crouched, player.Character.Crouched));jump.Add(new TwoWayBinding(player.Character.IsSupported, jump.IsSupported));jump.Add(new TwoWayBinding(player.Character.HasTraction, jump.HasTraction));jump.Add(new TwoWayBinding(player.Character.LinearVelocity, jump.LinearVelocity));jump.Add(new TwoWayBinding(jump.SupportEntity, player.Character.SupportEntity));jump.Add(new TwoWayBinding(jump.SupportVelocity, player.Character.SupportVelocity));jump.Add(new Binding(jump.AbsoluteMovementDirection, player.Character.MovementDirection));jump.Add(new Binding(jump.WallRunState, wallRun.CurrentState));jump.Add(new Binding(jump.Rotation, rotation.Rotation));jump.Add(new Binding(jump.Position, transform.Position));jump.Add(new Binding(jump.FloorPosition, floor));jump.Add(new Binding(jump.MaxSpeed, player.Character.MaxSpeed));jump.Add(new Binding(jump.JumpSpeed, player.Character.JumpSpeed));jump.Add(new Binding(jump.Mass, player.Character.Mass));jump.Add(new Binding(jump.LastRollKickEnded, rollKickSlide.LastRollKickEnded));jump.Add(new Binding(jump.WallRunMap, wallRun.WallRunVoxel));jump.Add(new Binding(jump.WallDirection, wallRun.WallDirection));jump.Add(new CommandBinding(jump.WalkedOn, footsteps.WalkedOn));jump.Add(new CommandBinding(jump.DeactivateWallRun, (Action)wallRun.Deactivate));jump.FallDamage = fallDamage;jump.Predictor = predictor;jump.Bind(model);jump.Add(new TwoWayBinding(wallRun.LastWallRunMap, jump.LastWallRunMap));jump.Add(new TwoWayBinding(wallRun.LastWallDirection, jump.LastWallDirection));jump.Add(new TwoWayBinding(rollKickSlide.CanKick, jump.CanKick));jump.Add(new TwoWayBinding(player.Character.LastSupportedSpeed, jump.LastSupportedSpeed));wallRun.Add(new Binding(wallRun.IsSwimming, player.Character.IsSwimming));wallRun.Add(new TwoWayBinding(player.Character.LinearVelocity, wallRun.LinearVelocity));wallRun.Add(new TwoWayBinding(transform.Position, wallRun.Position));wallRun.Add(new TwoWayBinding(player.Character.IsSupported, wallRun.IsSupported));wallRun.Add(new CommandBinding(wallRun.LockRotation, (Action)rotation.Lock));wallRun.Add(new CommandBinding(wallRun.UpdateLockedRotation, rotation.UpdateLockedRotation));vault.Add(new CommandBinding(wallRun.Vault, delegate() { vault.Go(true); }));wallRun.Predictor = predictor;wallRun.Add(new Binding(wallRun.Height, player.Character.Height));wallRun.Add(new Binding(wallRun.JumpSpeed, player.Character.JumpSpeed));wallRun.Add(new Binding(wallRun.MaxSpeed, player.Character.MaxSpeed));wallRun.Add(new TwoWayBinding(rotation.Rotation, wallRun.Rotation));wallRun.Add(new TwoWayBinding(player.Character.AllowUncrouch, wallRun.AllowUncrouch));wallRun.Add(new TwoWayBinding(player.Character.HasTraction, wallRun.HasTraction));wallRun.Add(new Binding(wallRun.LastWallJump, jump.LastWallJump));wallRun.Add(new Binding(player.Character.LastSupportedSpeed, wallRun.LastSupportedSpeed));player.Add(new Binding(player.Character.WallRunState, wallRun.CurrentState));input.Bind(rollKickSlide.RollKickButton, settings.RollKick);rollKickSlide.Add(new Binding(rollKickSlide.EnableCrouch, player.EnableCrouch));rollKickSlide.Add(new Binding(rollKickSlide.Rotation, rotation.Rotation));rollKickSlide.Add(new Binding(rollKickSlide.IsSwimming, player.Character.IsSwimming));rollKickSlide.Add(new Binding(rollKickSlide.IsSupported, player.Character.IsSupported));rollKickSlide.Add(new Binding(rollKickSlide.FloorPosition, floor));rollKickSlide.Add(new Binding(rollKickSlide.Height, player.Character.Height));rollKickSlide.Add(new Binding(rollKickSlide.MaxSpeed, player.Character.MaxSpeed));rollKickSlide.Add(new Binding(rollKickSlide.JumpSpeed, player.Character.JumpSpeed));rollKickSlide.Add(new Binding(rollKickSlide.SupportVelocity, player.Character.SupportVelocity));rollKickSlide.Add(new TwoWayBinding(wallRun.EnableEnhancedWallRun, rollKickSlide.EnableEnhancedRollSlide));rollKickSlide.Add(new TwoWayBinding(player.Character.AllowUncrouch, rollKickSlide.AllowUncrouch));rollKickSlide.Add(new TwoWayBinding(player.Character.Crouched, rollKickSlide.Crouched));rollKickSlide.Add(new TwoWayBinding(player.Character.EnableWalking, rollKickSlide.EnableWalking));rollKickSlide.Add(new TwoWayBinding(player.Character.LinearVelocity, rollKickSlide.LinearVelocity));rollKickSlide.Add(new TwoWayBinding(transform.Position, rollKickSlide.Position));rollKickSlide.Predictor = predictor;rollKickSlide.Bind(model);rollKickSlide.VoxelTools = voxelTools;rollKickSlide.Add(new CommandBinding(rollKickSlide.DeactivateWallRun, (Action)wallRun.Deactivate));rollKickSlide.Add(new CommandBinding(rollKickSlide.Footstep, footsteps.Footstep)); I ran into tons of problems. I created binding cycles that caused infinite loops. I found out that initialization order is often important, and initialization is a nightmare with data binding, with some properties getting initialized multiple times as bindings are added. When it came time to add animation, I found that data binding made it difficult and non-intuitive to animate between two states. And this isn't just me. Watch this Netflix talk which gushes about how great React is before explaining how they have to turn it off any time they run an animation. I too realized the power of turning a binding on or off, so I added a new field:class Binding{ public bool Enabled;} Unfortunately, this defeated the purpose of data binding. I wanted to get rid of UI state, and this code actually added some. How can I eliminate this state? I know! Data binding!class Binding{ public Property Enabled = new Property { Value = true };} Yes, I really did try this briefly. It was bindings all the way down. I soon realized how crazy it was. How can we improve on data binding? Try making your UI actually functional and stateless. dear imgui is a great example of this. Separate behavior and state as much as possible. Avoid techniques that make it easy to create state. It should be a pain for you to create state. Conclusion There are many, many more embarrassing mistakes to discuss. I discovered another "creative" method to avoid globals. For some time I was obsessed with closures. I designed an "entity" "component" "system" that was anything but. I tried to multithread a voxel engine by sprinkling locks everywhere. Here's the takeaway: Make decisions upfront instead of lazily leaving them to the computer. Separate behavior and state. Write pure functions. Write the client code first. Write boring code. That's my story. What horrors from your past are you willing to share? If you enjoyed this article, try these: The Poor Man's Voxel Engine The Poor Man's Character Controller One Weird Trick to Write Better Code
  4. Best explanation I've seen of quaternions, complete with Blender practical application tips https://t.co/MVxF1Pb5cE
  5. RT @MarkPuente: The best letter to the editor in today's @TB_Times. https://t.co/E60kou9BXw
  6. woah guys i actually kinda did an animation https://t.co/6Q7hoBIm1R
  7. RT @Oniropolis: Never tire of this. The video game as poetry. https://t.co/VsAX4olICo https://t.co/nFycOUPXp3
  8. YES! More awesome devs coming to the Midwest! We live cheap! And we don't even mind if you pick that state up north https://t.co/R1Dhjdq22V
  9. What percentage of a relationship would you say happens over text these days?
  10. Anyone planning on attending Handmade Con 2016? https://t.co/x3Rs6ruCdw
  11. Allow me to regale you with an exciting tale: the birth of a janky dialogue and voice system. I have a JSON file with all the localized strings in my game, like this:{ "danger": "Danger", "level": "Level %d", ...} A preprocessor takes this and generates a header file with integer constants for each string, like this:namespace strings{ const int danger = 0; const int level = 1; // ...} At runtime, it loads the JSON file and hooks up the integer IDs to localized strings. A function called "_" takes an integer ID and returns the corresponding localized string. I use it like this:draw_string(_(strings::danger), position); This all worked (and still works) pretty well for UI strings. Not so much for dialogue. To write dialogue, I had to come up with a unique ID for each line, then add it to the strings file, like this:{ "hello_penelope": "Hello! I am Penelope.", "nice_meet_you": "Nice to meet you.", ...} Yes, the preprocessor generated a new integer ID in the header file every time I added a line of dialogue. Gross. I construct dialogue trees in Dialogger. With this setup, I had to use IDs like "hello_penelope" rather than actual English strings. Also gross. A better way I keep the string system, but extend it to support "dynamic" strings loaded at runtime that do not have integer IDs in the header file. Now I can write plain English in the dialogue trees. The preprocessor goes through all of them and extracts the strings into a separate JSON file, using the SHA-1 hash of each string for its ID. Once everything is loaded, I discard all string IDs in favor of integer IDs. I couldn't find a simple straightforward SHA-1 implementation that worked on plain C strings, so here's one for you. The point of all this is: I now have a single JSON file containing all the dialogue in the game. Ripe for automation... Speak and spell Penelope is an AI character. I'm using text-to-speech for her voice, at least for now. I don't want to integrate a text-to-speech engine in the game; that's way too much work. And I don't want to manually export WAVs from a text-to-speech program. Also too much work. I create a free IBM Bluemix account. They have a dead simple text-to-speech API: make an HTTP request with basic HTTP authentication, get a WAV file back. I write an 82-line Python script that goes through all the dialogue strings and makes an HTTP request for each one. It keeps track of which strings have previously been voiced, to facilitate incremental updates. Now I have a folder of WAV files, each one named after a SHA-1 hash. I'm using Wwise for audio, so the next step requires a bit of manual involvement. I drag all the WAVs into the project and batch create events for them. Now when I display a dialogue string, I just have to look up the SHA-1 hash and play the audio event. Easy. Disaster strikes I don't hear anything. All signs indicate the audio is playing correctly, but nothing comes out of my speakers. I look at one of the audio files in Wwise. Looks like the file is corrupted. I play the WAV in a number of different programs. Some play it fine, others don't play it at all. I edit my text-to-speech script to use Python's wave library to load the WAV file after downloading it from IBM. Sure enough, the library doesn't know what to make of it. Too lazy to care, I edit the wave library in-place in my Python distribution. YOLO. After a bit of printf debugging, I pinpoint the issue. The WAV format is based on RIFF, a binary format which breaks the file into "chunks". According to Wikipedia, the format of each chunk is as follows: 4 bytes: an ASCII identifier for this chunk (examples are "fmt " and "data"; note the space in "fmt "). 4 bytes: an unsigned, little-endian 32-bit integer with the length of this chunk (except this field itself and the chunk identifier). variable-sized field: the chunk data itself, of the size given in the previous field. a pad byte, if the chunk's length is not even. Turns out, IBM's text-to-speech API generates streaming WAV files, which means it sets the "length" field to 0. Some WAV players can handle it, while others choke. Wwise falls in the latter category. Fortunately, I can easily figure out the chunk length based on the file size, modify it using the wave library, and write it back out to the WAV file. Like so. Problem solved. Wwise is happy. Next I set up some Wwise callbacks to detect the current volume of Penelope's voice, and when she's done speaking. Here's the result, along with some rope physics in the background being destroyed by the wonky framerate caused by my GIF recorder: If you want to hear it, check out the IBM text-to-speech demo here. Thanks for reading! Mirrored on my blog
  12. RT @ADAMATOMIC: @fasterthanlime "dada are you just randomly trying different sin() / cos() -1/1 variations until you get what you want" "..…
  13. It's not just cygwin, it's actual Linux binaries running on Windows. It intercepts and translates Linux syscalls. https://t.co/YlloZZTGwl
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