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.
• UnityCG.cginc - commonly used global variables and 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 mostly declares various preprocessor macros to aid in multi-platform shader development.

UnityCG.cginc

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

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.