Fast mobile shaders or rather Mobile! Fast!

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Varyings / Interpolants••Pass data from vertex to fragmentMost GPUs: minimize count & pack• PowerVR, not so much!•Usually much cheaper to use morevaryings if it helps avoiding indirecttexture reads• Likewise, do not pack 2 UVs into onefloat4/vec4 varying for PowerVROn PowerVR, varyings are very cheap (NOT like almost all other GPUs). Using more varyingscan be a big win there if it helps avoid doing some math in the shader.One particular case: texture2D(...,var.xy) is good on PVR; texture2D(...,var.zw) is bad - theGPU treats it as a dependent texture read which can’t be prefetched. So do NOT pack two UVsinto one vec4 varying if you care about PowerVR performance!
Shader Performance•Some shaders• color• texture• texture * color• diffuse normal map w/ dir. light• no light/material colors; light color; light+mat colors• specular Blinn-Phong w/ dir. light• approx. per vertex specular; full per pixelPerformance experiments with some shaders, from the simplest possible one to relativelycomplex for mobile (fully per-pixel Blinn-Phong)
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Fast mobile shadersor ratherMobile!
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Outline• Desktop vs. Mobile• GP
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Mobile•••Needs to use 100x le
Page 7 and 8: Old Is New•Techniques from 2001 i
Page 9 and 10: Workload••Frequency of computat
Page 11 and 12: Scene•••Opaque is the bestAvo
Page 13 and 14: “Onload” CPU?••More fast co
Page 15 and 16: GPU Species••••ImgTec Power
Page 17 and 18: Architectures•Tiled Deferred• P
Page 19 and 20: Case: HSR Performance•0.8-3.5ms t
Page 21 and 22: Hidden Surface Removal•Simple geo
Page 23 and 24: Saving BW & ALU•Framebuffer write
Page 25 and 26: Tiled Framebuffers•Higher Z preci
Page 27 and 28: Case: MSAA•4xMSAA, iPad2• 6ms i
Page 29 and 30: Case: Mipmaps•••Turn off mipm
Page 31 and 32: Case: OptimizingSHADOWGUN forTegra
Page 33 and 34: SHADOWGUN+Tegra2••Target 30 FPS
Page 35 and 36: Sort opaque geometry!•Saved ~15ms
Page 37 and 38: LUT Baking ToolsAnother bonus: sinc
Page 39 and 40: Texture Compression•••Tegra h
Page 41 and 42: Profiling toolsTools
Page 43 and 44: PVRUniSCoPVRUniSCo gives cycles for
Page 45 and 46: PerfHUD ES
Page 47 and 48: Tools: Android + Adreno•Adreno Pr
Page 49 and 50: Shader Performance
Page 51 and 52: GLSL ES specific•Precision qualif
Page 53 and 54: General Intuition•••Note: Han
Page 55 and 56: Precision: half / mediump••16 b
Page 57: Precision•Minimize conversion bet
Page 61 and 62: Shader Performance••Normalized
Page 63 and 64: Relative Performance•All lines in
Page 65 and 66: Unannouced TitleHigh poly, lots of
Page 67 and 68: Current state••37FPS after opti
Page 69 and 70: Getting GPU time on iOS•Force CPU
Page 71 and 72: Post-processing•Precision: lowp/f
Page 73 and 74: Burning Walls shader
Page 75 and 76: Burning Walls shader•Saved ~8ms p
Page 77 and 78: Optimize Particles•Reduce overdra
Page 79 and 80: Case: AngryBots
Page 81 and 82: AngryBots••Not much optimizatio
Page 83 and 84: Added for PC•••Depth of Field
Page 85 and 86: Wet floor•Render subset of scene
Page 87 and 88: Planar reflection
Page 89 and 90: Albedo
Page 91 and 92: Gloss (A of albedo tex)
Page 93 and 94: Pixel shader
Page 95 and 96: Splashes: geom + atlasWater splashe
Page 97 and 98: Post-fx costs••At native device
Page 99 and 100: Combine post-fx•Color Correction
Page 101 and 102: Cheat a bit•Scratch texture on no
Page 103 and 104: FXAA•Fast Approximate AA• Post
Page 105 and 106: Fail #1•FXAA is all float/highp
Page 107 and 108: Win #1•Use more (5) vec2 varyings
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FXAA 3.11•Latest FXAA 3.1 “cons
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Optimizing FXAA 3.11•Down to 12.7
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Extra SlidesExtra stuff we had init
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“Proper way”•Bake a bunch of
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Actually reflectedThis is what is a
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Ta-da!
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Reflection UVs••Not much physic
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Without Bloom
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Also Color Adj•Can also do simple
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“Mood Boxes” in Unity 3.4 Angry
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Mood Boxes•When entering new mood
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Fast mobile shaders or rather Mobile! Fast!

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