Gaming Technologies

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

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Games Yesterday Today
Quake 2 - 1997
Prince of Persia - 1989
Doom - 1993
Far Cry - 2004
Max Payne - 2001
Age of Empires III
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Game Components
Content Engine
Platform
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Content Components
sound
effects
scripting

• as well as
• user interface

story
lighting
Content
modeling
level design
animation
texturing / surfacing
visual technologies
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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

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Game Engine Components
AI
Graphics
Physics
Engine

• as well as
• installation
• patching
• resource management
• multithreading
• disk i/o
• state save/restore

Networking I/O
Audio
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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

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

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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!

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Other Platforms

• Hand-held
• Dedicated consoles (PSP, Gameboy)
• Controller-like input
• Mobile phones
• 700M phones/year
• Non-uniform platform
• Keypad input
• Modest resolution (320x200 640x480)
• 1995-class PC graphics
• Arcade
• Industrial version of home console?

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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

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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
• Dont specify non-observable implementation
  details
• Use virtual machine model

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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)

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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

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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)

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

• 2004-2005 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

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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

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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

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HardwareLots of Room To Grow?

• Enthusiast GPU today (soon)
• 1-2 Teraflops
• 110-90nm
• 300-350M transistors
• 80 Watts
• Increasing attention on
• power
• efficiency

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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

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GPU as Solution

• How best to use performance increases?
• CPU bottlenecks
• Offload more processing to the GPU?
• Simulations, physics?
• Content
• Support greater detail
• Dont create more work for artists
• Procedural detail?

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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

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Scene Composition Post

• Post effects becoming common place
• HDR, bloom, tints, grain, motion blur, depth of
  field .
• Global atmosphere
• Dont 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

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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

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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?

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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

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Texture Maps

• Resolution increasing rapidly
• 4Kx4K high-resolution maps
• Nearing the 8Kx8K used for film
• Too much work to paint this much detail
• Dont paint individual skin pores
• Digital camera capture not the answer
• 4Kx4K RGBA 32MB _at_ 2x compression

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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

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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

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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?

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Skinned Control Mesh
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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

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Games Tomorrow
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Questions