FOOTBALL AT 60 FPS: FOOTBALL AT 60 FPS: The Challenges of Rendering Madden NFL 10.
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Transcript of FOOTBALL AT 60 FPS: FOOTBALL AT 60 FPS: The Challenges of Rendering Madden NFL 10.
FOOTBALL AT 60 FOOTBALL AT 60 FPS: FPS: The Challenges of Rendering Madden NFL 10
Introduction
• Jayeson Lee-Steere– Technical Director for Football’s Central
Graphics & Infrastructure– 7 Years with EA Tiburon– 17 Years in Industry
• Joe Harmon– Lead Technical Artist for Madden NFL
Football– 4 Years with EA Tiburon
Overview
• Challenges facing Madden Football• Shader Authoring Workflow• Lighting Workflow• Fields• Faces• Crowd Rendering• Colorization and Texture Compositing
The Challenges of Rendering Madden Football
Madden Rendering Challenges
• Scale– 60,000+ characters on screen– 100+ characters on field – authentic stadium– realistic grass– costly post effects
• Lighting Variation– geographic locations– time of day– weather conditions
• Raising the bar– 6 iterations between 360/PlayStation 3– 30fps -> 60fps
Shader Authoring Workflow
Shader Authoring Workflow
• Madden shaders authored primarily by Technical Artists
• Each shader is custom written for its application
• No ‘do everything’ shaders
• Shaders written using a variant of HLSL which compiles for both xbox 360 and ps3
• We use a custom version of Maya that allows artists to view the same real time shaders as used in game.
• Artists set and tune material parameters within Maya
Maya rendering with game shaders
Shader Authoring Workflow
• The Madden rendering technology automatically binds runtime variables to shader parameters to improve efficiency of rendering• Normalizing the light direction• Player Numbers and names
Lighting Workflow
Lighting Workflow
• Lighting is key for realistic sports rendering
• Realistic lighting can also get expensive• Madden’s lighting solution is a hybrid of
baked and real-time lighting– Increases efficiency
• Environment objects and characters have separate lighting functions– Allows individual tuning for unique settings– Character lighting is more expensive
Lighting Workflow
• All Madden shaders use global lighting functions– Important for consistency– Global changes can be made quickly
• Environment lighting formula:– Color texture * (diffuse + ambient + night
bake)– Night bake = vertex color * occlusion texture
• Character lighting formula:– Color texture * (diffuse + ambient) + specular– Specular = rim spec + cube spec + direct spec
Lighting Workflow
• Nearly all lighting tuned live in game• Lighting parameters controlled
through blending files (basically XML) authored by lighting artists
• Each BLE has keyframes for times of day
• Lighters use our lighting tool, Glint, to adjust lighting parameters
• Lighters control post effects through Glint
Glint
Time of day
Fields
View of field from game play camera
Fields
• Field rendering is challenging due to the size of the field– A small shader change can have a large
performance cost
• Field rendering Performance and visual quality impact one another and must be balanced
• The Field must support dynamic degradation and weather effects• Tunable through glint
Field Texture Components
Field with no degradation
Field with heavy degradation
Field with snow
Faces
Faces
• Madden has 29 high res face texture sets loaded at any given moment• 22 Players• 2 Coaches• 5 Referees
• Maintaining high visual quality becomes challenging due to memory limitations
• Player heads consistently loading and unloading
Hue, Saturation, Value (HSV)
• HSV is a color space, like RGB• Hue: A color• Saturation: The amount of a color• Value: The darkness of a color
• Storing the color information in HSV format allows each channel to be compressed individually when using separate textures
RGB Hue Saturation Value
Hue, Saturation, Value (HSV)
• The Hue texture is the RGB representation of Hue• Storing the Hue as an RGB texture avoids
costly shader math when converting HSV to RGB
• Once the Hue is stored as RGB into a texture the shader logic becomes simpleFloat3 Hue = tex2D(hueSampler, texCoords);Float3 Sat = tex2D(satSampler, texCoords);Float3 Val = tex2D(valSampler, texCoords);
Float3 finalColor = lerp(1, Hue, Sat) * Val;
Hue, Saturation, Value (HSV)
• The Hue and Saturation can be combined into a single texture for optimization
• We call the combined texture ‘chroma’Float3 Chroma = tex2D(chromaSampler, texCoords);Float3 Val = tex2D(valSampler, texCoords);
Float3 finalColor = Chroma * Val;
RGB Hue andSaturation combined
Value
One DXT5 512x256 texture One 128x128 A8R8G8B8One 512x512 DXT1
One DXT5 512x256 texture One 128x128 A8R8G8B8
One 512x512 DXT1
Crowd Rendering
Crowd Rendering
• Not about card rendering• About 3D characters that:– Support swap parts for variety– Are easy to author– Render super fast• = one shader, one set of shader
parameters*, one draw for everyone
* We call a shader selection + set of parameters a material
Crowd Rendering
Crowd Rendering
• Can we just author the previous group as one mesh with one material?– Yes, we’ve done this– Have to duplicate it to get enough people– Lots of redundant authoring (e.g.
duplicating mesh parts to assign unique UV’s)
– Character locations fixed– Obvious patterns show up– Some workarounds possible but difficult,
hacky and reduces performance
Crowd Rendering
• Authoring for our solution–Make skinned meshes like usual– Restriction 1: All must use the same
shader– Restriction 2: All textures must be the
same size– Can have lots of meshes, materials– Swap parts defined using an existing
technique– Now we need some pipeline/runtime
magic to turn that into one draw call
Crowd Rendering
• The pipeline/runtime magic– Collapse to one mesh• Similar to standard instanced rendering
techniques
– Collapse to one material• Copy all parameters into one
– Collapse textures to texture atlas– Technical details in appendix slides
Crowd Rendering
• Good– Authoring– Extensible content– Super fast (100x
+)– Variety
• Bad– Complicated
shader– Complicated
pipeline/runtime
– 1 shader (alpha?)
Colorization and texture compositing
Colorization and Texture Compositing• Common methods of authoring
shaders:– Shader language• e.g. HLSL
– Visual, node based• Maya layered shader, Houdini, etc.• Converted to shader language for game?
• What about a hybrid?– Node based– Each node is a HLSL shader
Colorization and Texture Compositing• Our node + shader language
implementation– Performs a rendering step for each node• The inputs are textures and other
parameters• The output is a texture
–Mostly used to bake results at load time– A sort is performed so that nodes are
rendered in optimal order for memory usage
ExampleSelectSelect
ColorizeColorize ColorizeColorize
CompositeComposite
CompositeComposite
Selection
ColorsColors
Colorization and Texture Compositing• Insights• A handful of generic shaders meet
majority of needs• Select• Colorize• Composite
• More intermediate textures actually reduces memory overhead• No need to create do-all-in-one-step shaders
Questions?
Appendix: Crowd Tech Details
• Mesh collapsing– General solution
• Put all vertex data in one giant vertex buffer• For each character, copy swap part indices to
one new index buffer per character• Use standard instanced rendering techniques
to draw multiple characters at once
– Software vertex pipeline (e.g. SPU)• Modify to combine output vertex data into a
big buffer• Most flexible option, can make every
character have unique look, behavior and animation
Appendix: Crowd Tech Details
• Material Collapsing– Assign each material an index– Copy index into vertex data– Unique per material parameters copied to
shader constant array (e.g. float4 params[])• Texture assignments• Specular power• Colorization choices• etc.
– Shader uses index in vertex data to look up material parameters
Appendix: Crowd Tech Details
• Texture Collapsing– No texture [] in shader language– Tile each texture into one large texture
(atlas)– Store texture index in float []– Shader uses index to do UV offset