Craig Peeper Software Architect Windows Graphics & Gaming Technologies Microsoft Corporation

Transcription

1 Gaming Technologies Craig Peeper Software Architect Windows Graphics & Gaming Technologies Microsoft Corporation

2 Overview Games Yesterday & Today Game Components PC Platform & WGF 2.0 Game Trends Big Challenges in Game Creation Summary

3 Games Yesterday & Today Prince of Persia Doom Quake Max Payne Far Cry Age of Empires III

4 Game Components Content + Engine Platform

5 Content Components scripting sound effects as well as user interface story lighting Content modeling level design texturing / surfacing animation visual technologies

6 Content Creation Tool driven Combination of tools forms Art Pipeline Character Pipeline 3D Model/Sculpting Animation/Rigging Skinning Texturing Lighting/Shading An artist often specializes on one part of pipeline

7 Game Engine Components AI Graphics Physics Audio Engine Networking + I/O as well as installation patching resource management multithreading disk i/o state save/restore

8 Game Engines Studio chooses to build or buy Quake Source, Unreal engines Renderware, Gamebryo middleware Often come with great authoring tools (level editors, etc.) Componentized software May buy specialized components How many people can write a physics engine? Video codecs, etc Engine may be optimized for game genre/style Engine bounds range of content Global illumination, terrain, indoor scenes

9 Game Platform Components CPU + Memory Graphics Storage SW + HW Platform Audio Networking + Input

10 Game Platforms Console 10M 100M installed base fixed platform Moderately powerful hardware Standard & High definition video resolution (1080i, 720p) Controller, wheel (& keyboard, mouse) input Refreshed every 4-5 years 10 experience on TV

11 Game Platforms (cont.) PC 600M installed base (running Microsoft Windows) Non-uniform platform (video cards, memory, CPU) Most powerful hardware Least powerful too Very high resolution (1600x1200, 1920x1080, ) Keyboard, mouse (& controller) input 2 & 10 (desk vs living room) Notebook (portable gaming) Upgraded yearly!

12 Other Platforms Hand-held Dedicated consoles (PSP, Gameboy) Controller-like input Mobile phones 700M phones/year Non-uniform platform Keypad input Modest resolution (320x x480) 1995-class PC graphics Arcade Industrial version of home console?

13 PC as a Platform Large installed base Least expensive to publish on No platform royalties Large hw variation, rapidly evolving Large number of support calls Supports rapid innovation Profit from selling PC hardware! Games must span variability Influences content & engine Reach versus development cost Challenges Abstract hardware differences in platform Support innovation

14 New Direction for PC Platform Reduce unnecessary hardware variation Programmable hardware causes new problems Shading programs are part of content not engine Shading programs more complex Content must be portable & reusable Approach: Specify details that matter Representation, precision, accuracy Don t specify non-observable implementation details Use virtual machine model

15 Windows Graphics Foundation 2.0 Maintain consistent feature set Eliminate capability bits (optional features) Well defined behavior Multiple implementations produce same result E.g., IEEE-754 arithmetic Migrate legacy fixed functions to shaders Fixed-function lighting, alpha test, etc Consistent shader programming model Vertex and pixel shaders use common instruction set Obsolete assembly level programming Add optimizations where large benefit Scenario-specific formats (high dynamic range, normal maps)

16 Innovation in WGF 2.0 Integer & floating-point processing More general data flow Stream out to memory after vertex processing Unify textures, render targets, vertex buffers Arrayed resources Select array element to render to in shader Enables single-pass render to cube map New pipeline stage (geometry shader) Whole-primitive processing

17 Geometry Shader Shader stage that sees whole primitive 3 vertices of a triangle (or 2 vertices of a line) As well as adjacency (6 vertices per triangle) Can compute per-primitive data Pass to pixel shader Barycentric parameters Plane equations Can amplify data Extrude edges, expand points, generate shells Find silhouette edges Limited amplification (not a general tessellator)

18 WGF 2.0 Pipeline fixed programmable memory Constant Constant Constant Input Assembler Vertex Shader Geometry Shader Setup Rasterizer Pixel Shader Output Merger Sampler Sampler Stream out Sampler Vertex Buffer Index Buffer Texture Texture Stream Buffer Texture Depth Stencil Render Target Memory

19 Game Trends Record sales Visually stunning titles Half Life 2, Halo 2, Far Cry, Doom 3 Largest worlds Most detailed levels of realism Not just graphics: AI, physics, animation Longest development times Largest development costs Bulk of cost in producing content Increasing ratio of artists : programmers

20 Trends - Software Demand for larger worlds Demand for more detail Floppies vs CDs vs DVDs HALO2 4.2GB HD-DVD/Blueray 20GB Rising development cost Content creation is the bottleneck $10M content budget Art Pipeline is not scaling Amortize cost over multiple platforms

21 Trends Hardware CPU performance Clock speed brick wall Transition to multi-core CPUs Games are CPU-limited Games are tuned until they are not GPU-limited PC & consoles GPU performance 2x increase every 2 years

22 Hardware Lots of Room To Grow? Enthusiast GPU today (soon): 1-2 Teraflops nm ~ M transistors ~80 Watts Increasing attention on power efficiency

23 Game Development Challenges Creating & Managing Detail Scalable process for content creation CPU overload Multi-core not a panacea Volume of data Effective run-time management of data Tool power & expressiveness Traditional tools not powerful enough

24 GPU as Solution How best to use performance increases? CPU bottlenecks Offload more processing to the GPU? Simulations, physics? Content Support greater detail Don t create more work for artists Procedural detail?

25 Procedural Detail Techniques used in film production Scene Composition & Post Processing Translucency & Antialiasing Filter & Blend Texture Detail Procedural generation Modeling & Animation Tessellation + Displacement/Normal Maps

26 Scene Composition & Post Post effects becoming common place HDR, bloom, tints, grain, motion blur, depth of field. Global atmosphere Don t merge into individual assets Next step, on the fly Apply to individual scene elements Composite scene elements together Use to break up the scene detailing

27 Composition Commonly use render target blending Porter-Duff composition More generally use pixel shader to Apply curves and filters (blurs) Limiting factors Performance Transparency & depth compositing

28 Transparency Traditionally render back to front with blend Sort on CPU Interactions with other algorithms (e.g., shadows) Different algorithms for Objects with feathered edges (trees) Transparent objects (windows) Volumetric effects (particle systems) Opacity versus Coverage Use alpha to represent both Can we solve with hardware?

29 Unsorted Transparency Traditionally solved with a-buffer algorithm Save all of the pixel fragments for each pixel Resolve at end of frame Arbitrary number of fragments per pixel Lists (linked), dynamic allocation Look at good enough solutions Save some maximum number of fragments Fixed-function or programmable solution? Fixed-function more efficient, but extra hardware

30 Texture Maps Resolution increasing rapidly 4Kx4K high-resolution maps Nearing the 8Kx8K used for film Too much work to paint this much detail Don t paint individual skin pores Digital camera capture not the answer 4Kx4K RGBA = 2x compression

31 Texture Maps GPU virtual memory helps with size, but Can we ever really store enough resolution? A better way? Use procedural texture techniques Shaders now expressive enough Do they have enough performance? Artists concentrate on form Algorithmically add detail paint algorithm ids

32 Surfaces and Tessellation Increasing character complexity 2K 5K 15K triangles/character Increased skinning and morphing complexity k weights for each vertex Hand-tuned for animation Silhouette edges still look poor Compared to lighting and shading quality Alternative use higher-order surfaces Beziers, Catmull-Clark subdivision, NURBS, Many studios already model with surfaces Convert to triangles when packaging content

33 Tessellation Advantages Animate and skin the control mesh Less computation than per-vertex Tessellate the resulting control mesh Combine with displacement mapping Use for additional geometric detail Adds detail to silhouette edges Use normal maps for fine shading detail Combine with adaptive tessellation?

34 Skinned Control Mesh

35 Summary Games increasingly more complex World size, detail Bulk of cost in producing content Content creation process not scaling Amortize cost over multiple platforms Try to reduce cost of additional detail Run-time generation of detail Improved tools for controlling detail Good areas for additional research

36 Games Tomorrow

37 Questions