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The nitty gritty of game development
- 1. The Nitty Grittyof Game Development Life in and around the Game Industry
- 2. NVIDIA Corporation Overview ―Quick‖ Bio Anatomyof the Game Industry Engine components Life as a Game Developer Getting there from here
- 3. NVIDIA Corporation ―Quick‖ Bio 2002-2003Electronic Arts Command & Conquer Generals Design Support / Audio / Optimization 2003-2005 TimeGate Studios Kohan Kings of War, Axis & Allies Graphics / Audio / Optimization
- 4. NVIDIA Corporation ―Quick‖ Bio 2005-2009NVIDIA Corporation - Architecture 8800, 9800, gt 2xx Performance Simulators 2009-Pres NVIDIA Corporation - Developer Technology Wut
- 5. NVIDIA Corporation Developer Technology GameOptimization Developer Education GDC, Siggraph, etc New feature integration Tessellation 3D Vision Research Realtime Per-face Texture Mapping PN-AEN triangles (crack-free PN triangles)
- 6. NVIDIA Corporation Anatomy ofthe Game Industry Developers Make Games Publishers Finance Games Advertise First Party – Developers that are owned by a publisher Bioware, id, Maxis, Ensemble (RIP) Third Party – Independent development houses Valve, Epic, Gearbox
- 7. NVIDIA Corporation Developers from10’ Large developers often split into two or more teams: Engine Team (usually one) Game Team (usually one per title in simultaneous development) Engine Team focuses on reusable components Game Team focuses on everything needed for one game Other aspects of Game Development Art – Models, Textures, Animation Sound / Music Design – Level design, Gameplay design, etc Q/A – Make sure everything works! Production – Everything else
- 8. NVIDIA Corporation Art pipelinefrom 5’ Art is a complex pipeline with many pieces Concept art – 2D artwork that conveys mood and tone Modeling – In a DCC such as 3DS Max or Maya Unwrap – Often combined with Modeling these days Sculpting – Creation of normal maps Rigging – Assigning a skeleton to vertices for animation / attachments Texturing – Material properties to be applied to a model Animation – Everything relating to model motion
- 9. NVIDIA Corporation Engine Components Modernengines are as complex as some OSes Filesystem GUI Controller input (Keyboard/Mouse/Gamepad) Windowing system Audio Rendering Threading / Fibers AI And have strong realtime requirements 60 Hz is only 16.66… ms
- 10. NVIDIA Corporation Filesystem? Problem: fopenis verrrrrrry slow Solution: WADs. Giant conglomeration of all files (at least of one type) needed by the game fopen only called once Header read from the file into memory As other data is needed, just fseek into the wad and fread big chunks But you don’t want everyone to have to know about the WAD Generally use Fseek or engine::fseek, etc.
- 11. NVIDIA Corporation GUI Today’s gamessupport complex, rich interaction with gamers Some embed complete HTML renderers (!!) Problems: Relying on the OS’s windowing system… Makes it harder to port Subjects the developer to OS bugs Solution: Homegrown Often built with Scaleform or similar technologies But still require significant game development and time One of the most important aspects for making a game feel ―tight‖
- 12. NVIDIA Corporation Audio Engine Scheduling,play and decode of audio effects Play and decode generally handled by the Miles Sound System ~10Ks of titles have used MSS Scheduling, pre-caching and prioritization still handled by application, though As well as placement and movement throughout the world Generally 32 or 64 voices can be dealt with at once Application prioritizes based on volume, importance, distance, etc Other samples are culled Avoid clipping!
- 13. NVIDIA Corporation Threading Amdahl’s Law:A system can only be as fast as the sum of the length of the critical path. By and large, games tend to be mostly single-threaded But this subjects them heavily to Amdahl’s Law Multithreaded programming is still hard Most common thread division Main Thread – Message Pump management, simulation updates Rendering Thread – Just issues D3D calls as fast as possible Loading Thread – Loads assets from disk asyncronously Main thread is still subject to Amdahl’s Law
- 14. NVIDIA Corporation Why notthread the simulation? For peer-to-peer topologies, this is very hard Need absolutely deterministic behavior on all clients To make this possible, would need to make agent updates commutative Client-Server is no picnic, either Still subject to all of the usual multithreading issues And client-server tends to have radically fewer agents
- 15. NVIDIA Corporation Rendering My personalfavorite Typically split into two phases View phase Draw phase View Phase makes broad determinations about visibility Simulation updates view objects, which always exist What is on screen? Near the screen? Far away? Which chunks need to be resident in memory? Which can be evicted from a cache and pushed back to disk?
- 16. NVIDIA Corporation View Phase(cont’d) Many types of visibility determination Chunking View Frustum culling (Bounding volume testing) Occlusion queries Quad or Oct trees Once an object is determined to be on or near screen It is submitted to the rendering queue, which will actually draw it If the data is not available to render, the view might ask to load it It might block (causing a stall—yuck) Or it might just say ―load this asap, we’ll skip it this frame‖ Avoiding stalls without breaking immersion is tricky
- 17. NVIDIA Corporation Draw Phase D3D9is still the most common :,( Consoles control this D3D11 is becoming more common OpenGL is (unfortunately) the Linux of graphics APIs Technically superior, but somewhat unloved 2008, THE YEAR OF OPEN/GL 2011, THE YEAR OF OPEN/GL 2015, THE YEAR OF OPEN/GL Fear not! Which API you know is less important than understanding the graphics pipeline.
- 18. NVIDIA Corporation Types ofRenderers Two main forms of real-time rendering Forward rendering Deferred rendering In forward rendering, objects are shaded final colors, including all lights, as you go If N is # objects and L is # lights, then naively this is O(N * L) Can mean waste as you render an object, then render something over the top of it. D’oh! Can be mitigated with a depth prepass First, only lay down depth Next, render objects, but use a depth test of == with no depth write
- 19. NVIDIA Corporation Deferred Rendering Deferredrendering is two-pass First pass, lay down material properties In theory, this is good, simple shaders In practice, this is fairly bandwidth intensive, which directly translates to W Second pass, apply lighting. For N objects and L lights, deferred rendering is O(N + L) Better! And no real need for a depth-only prepass
- 20. NVIDIA Corporation AI Broadly ―whatshould NPCs do?‖ Can often be a significant portion of the frame time More convincing AI is often more expensive But there are also ―tricks‖ that can look convincing without actually being expensive
- 21. NVIDIA Corporation Breakdown ofa frame In most games, Care and Feeding of the GPU is the most expensive CPU task Talking to the APIs is unfortunately expensive Better with D3D11 and OGL, but still an issue AI / Pathfinding is generally the second most expensive chunk of time Both suffer (fundamentally) from Amdahl’s Law: The GPU is a giant state machine, so it’s difficult to hold many conversations with it at once AI needs to reason about the game world, and that is hard to do if the game world isn’t frozen in time (at least briefly)
- 22. NVIDIA Corporation Life asa Game Developer
- 23. NVIDIA Corporation Life asa Game Dev Initially, very hard Expect long hours And comparatively low pay Many, many, many programmers want to be game developers Like all of you Multiplied by every college in the country Except University of Florida, because… Florida. But the game industry isn’t that big So supply and demand is working against labor
- 24. NVIDIA Corporation Life asa Game Dev (cont’d) Move Early, Move Often Most areas have 0-2 game developers (heavily skewed towards 0) This means as a developer, you will move geographically and frequently The game industry has an abnormally high divorce rate Approaching 75%. Yikes. Spouses often refer to themselves as widows with husbands/wives You do not play games for a living.
- 25. NVIDIA Corporation Crunch time Crunchis ubiquitous Even Valve Suckitude of crunch varies by employer Much better at Valve, id, EA (modern EA)
- 26. NVIDIA Corporation Still notdissuaded? Ship titles. Shipped titles are freedom in the game industry Figure out what’s important to you, and negotiate for that. You will be a peon for your first game. I’m sorry! To be fair, you’ll be a peon for your first gig regardless But Game Industry Peon << Any other industry Peon There are upsides Everyone you work with loves games as much as you do You get to work on your hobby You get immediate feedback about the cool shit you’ve done You can point to something tangible, and say ―I made that.‖ You will be the hero of kids everywhere
- 27. NVIDIA Corporation Getting therefrom here So how do you get there? Good fundamentals. I cannot stress this enough. Algorithm analysis, quick O estimations Computer organization and assembler Debugging Be sociable / personable Personal Projects / OSS
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Editor's Notes
- #6 Titles: DOTA 2, Portal 2, L4D2, StarCraft 2, Rage, UE3, Borderlands,