Gaming Technologies
Craig Peeper
Software Architect
Windows Graphics & Gaming Technologies
Microsoft Corporation
Overview
Games Yesterday & Today
Game Components
PC Platform & WGF 2.0
Game Trends
Big Challenges in Game Creation
Summary
Games Yesterday & Today
Prince of Persia - 1989
Max Payne - 2001
Doom - 1993
Far Cry - 2004
Quake 2 - 1997
Age of Empires III
Game Components
Content + Engine
Platform
Content Components
sound
effects
scripting
story
as well as …
• user interface
lighting
Content
modeling
level
design
texturing /
surfacing
animation
visual
technologies
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
Game Engine Components
AI
Graphics
Engine
Physics
Audio
Networking
+
I/O
as well as …
• installation
• patching
• resource management
• multithreading
• disk i/o
• state save/restore
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
Game Platform Components
CPU
+
Memory
Graphics
SW + HW
Platform
Storage
Audio
Networking
+
Input
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
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!
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?
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
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
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)
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
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)
WGF 2.0 Pipeline
fixed
programmable
memory
Input
Assembler
Constant
Constant
Vertex
Shader
Geometry
Shader
Sampler
Vertex
Buffer
Index
Buffer
Texture
Constant
Setup
Rasterizer
Sampler Stream out
Texture
Memory
Stream
Buffer
Pixel
Shader
Output
Merger
Sampler
Texture
Depth Render
Stencil Target
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
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
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
Hardware
Lots of Room To Grow?
Enthusiast GPU today (soon):
1-2 Teraflops
110-90nm
~300-350M transistors
~80 Watts
Increasing attention on
power
efficiency
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
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?
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
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
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?
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
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 = 32MB @ 2x compression
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
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
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?
Skinned Control Mesh
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
Games Tomorrow
Questions