Shader Compilation

Import time – when you create a .shader file

• compile the shader variants only when needed, etc. platform, variants

Build time – when you build a player

• [level 1] ShaderLab -> glsl or hlsl or …etc
  • if platform supports, from [level 2] hlsl -> IL or MetalSL to AIR…etc
• Cache identical shaders under Library/ShaderCache
• compile only not-yet-ever-compiled shaders (variants for this platform only)

Run time – when you open the app

• [level 3] glsl or hlsl or IL or AIR…etc -> driver (GPU bytecode)
  • because target device is unknown for PC/mobile at buildtime
• Depends on driver, when to compile these codes e.g. only when it’s used
  • use shader pre-warm to “use” shaders to trigger compilation

Sources from lukasc, robs, Unity Manual and https://blogs.unity3d.com/2014/05/06/shader-compilation-in-unity-4-5/