Fast mobile shaders or rather Mobile! Fast!

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It’s very hard (i.e. practically impossible) to get GPU timing for a draw call on TBDR, makingprofiling hard. Often easier to profile on Tegra or Adreno.Tiled Deferred Caveats••Scene splitsMore transistors for smarts• Less “raw power”•No GPU time per draw call• Easier to profile on non-TBDR: Tegra orAdrenoSo it seems that TBDR architecture is all awesome, but of course it has some drawbacks aswell.If vertex data per frame (number of vertices * storage required after vertex shader) exceedsthe internal buffers allocated by the driver, the scene has to be “split” which costsperformance. The driver might allocate a larger buffer after this point, or you might need toreduce your vertex count. We ran into this on iPad2 (iOS 4.3) at around 100 thousand verticeswith quite complex shaders.TBDR needs more transistors allocated for the tiling & deferred parts, leaving conceptuallyless transistors for “raw performance”.
Case: OptimizingSHADOWGUN forTegra 2Case study: optimizing SHADOWGUN
Page 1 and 2: Fast mobile shadersor ratherMobile!
Page 3 and 4: Outline• Desktop vs. Mobile• GP
Page 5 and 6: 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: Case: Mipmaps•••Turn off mipm
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 and 58: Precision•Minimize conversion bet
Page 59 and 60: Shader Performance•Some shaders
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
Page 109 and 110:
FXAA 3.11•Latest FXAA 3.1 “cons
Page 111 and 112:
Optimizing FXAA 3.11•Down to 12.7
Page 113 and 114:
Extra SlidesExtra stuff we had init
Page 115 and 116:
“Proper way”•Bake a bunch of
Page 117 and 118:
Actually reflectedThis is what is a
Page 119 and 120:
Ta-da!
Page 121 and 122:
Reflection UVs••Not much physic
Page 123 and 124:
Without Bloom
Page 125 and 126:
Also Color Adj•Can also do simple
Page 127 and 128:
“Mood Boxes” in Unity 3.4 Angry
Page 129:
Mood Boxes•When entering new mood
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Fast mobile shaders or rather Mobile! Fast!

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