Built-in shader include files

Unity contains several files that can be used by your shader programs to bring in predefined variables and helper functions. This is done by the standard #include directive, e.g.:

CGPROGRAM
// ...
#include "UnityCG.cginc"
// ...
ENDCG

Shader include files in Unity are with .cginc extension, and the built-in ones are:

• HLSLSupport.cginc - (automatically included) Helper macros and definitions for cross-platform shader compilation.
• UnityShaderVariables.cginc - (automatically included) Commonly used global variables.
• UnityCG.cginc - commonly used helper functions.
• AutoLight.cginc - lighting & shadowing functionality, e.g. surface shaders use this file internally.
• Lighting.cginc - standard surface shader lighting models; automatically included when you’re writing surface shaders.
• TerrainEngine.cginc - helper functions for Terrain & Vegetation shaders.

These files are found inside Unity application ({unity install path}/Data/CGIncludes/UnityCG.cginc on Windows, /Applications/Unity/Unity.app/Contents/CGIncludes/UnityCG.cginc on Mac), if you want to take a look at what exactly is done in any of the helper code.

HLSLSupport.cginc

This file is automatically included when compiling shaders. It declares various preprocessor macros to aid in multi-platform shader development.

UnityShaderVariables.cginc

This file is automatically included when compiling shaders. It declares various built-in global variables that are commonly used in shaders.

UnityCG.cginc

This file is often included in Unity shaders to bring in many helper functions.

Data structures in UnityCG.cginc

• struct appdata_base: vertex shader input with position, normal, one texture coordinate.
• struct appdata_tan: vertex shader input with position, normal, tangent, one texture coordinate.
• struct appdata_full: vertex shader input with position, normal, tangent, vertex color and two texture coordinates.
• struct appdata_img: vertex shader input with position and one texture coordinate.

Generic helper functions in UnityCG.cginc

• float3 WorldSpaceViewDir (float4 v) - returns world space direction (not normalized) from given object space vertex position towards the camera.
• float3 ObjSpaceViewDir (float4 v) - returns object space direction (not normalized) from given object space vertex position towards the camera.
• float2 ParallaxOffset (half h, half height, half3 viewDir) - calculates UV offset for parallax normal mapping.
• fixed Luminance (fixed3 c) - converts color to luminance (grayscale).
• fixed3 DecodeLightmap (fixed4 color) - decodes color from Unity lightmap (RGBM or dLDR depending on platform).
• float4 EncodeFloatRGBA (float v) - encodes [0..1) range float into RGBA color, for storage in low precision render target.
• float DecodeFloatRGBA (float4 enc) - decodes RGBA color into a float.
• Similarly, float2 EncodeFloatRG (float v) and float DecodeFloatRG (float2 enc) that use two color channels.
• float2 EncodeViewNormalStereo (float3 n) - encodes view space normal into two numbers in 0..1 range.
• float3 DecodeViewNormalStereo (float4 enc4) - decodes view space normal from enc4.xy.

Forward rendering helper functions in UnityCG.cginc

These functions are only useful when using forward rendering (ForwardBase or ForwardAdd pass types).

• float3 WorldSpaceLightDir (float4 v) - computes world space direction (not normalized) to light, given object space vertex position.
• float3 ObjSpaceLightDir (float4 v) - computes object space direction (not normalized) to light, given object space vertex position.
• float3 Shade4PointLights (...) - computes illumination from four point lights, with light data tightly packed into vectors. Forward rendering uses this to compute per-vertex lighting.

Vertex-lit helper functions in UnityCG.cginc

These functions are only useful when using per-vertex lit shaders (“Vertex” pass type).

• float3 ShadeVertexLights (float4 vertex, float3 normal) - computes illumination from four per-vertex lights and ambient, given object space position & normal.