Built-in shader helper functions

Unity has a number of built-in utility functions designed to make writing shaders simpler and easier.

Functions declared in UnityCG.cginc

See Built-in shader include files for an overview of shader include files provided with Unity.

Vertex transformation functions in UnityCG.cginc

Function:	Description:
float4 UnityObjectToClipPos(float3 pos)	Transforms a point from object space to the camera’s clip space in homogeneous coordinates. This is the equivalent of mul(UNITY_MATRIX_MVP, float4(pos, 1.0)), and should be used in its place.
float3 UnityObjectToViewPos(float3 pos)	Transforms a point from object space to view space. This is the equivalent of mul(UNITY_MATRIX_MV, float4(pos, 1.0)).xyz, and should be used in its place.

Generic helper functions in UnityCG.cginc

Function:	Description:
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.
float2 EncodeFloatRG (float v)	Encodes [0..1) range float into a float2.
float DecodeFloatRG (float2 enc)	Decodes a previously-encoded RG float.
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).

Function:	Description:
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.

Screen-space helper functions in UnityCG.cginc

The following functions are helpers to compute coordinates used for sampling screen-space textures. They return float4 where the final coordinate to sample texture with can be computed via perspective division (for example xy/w).

The functions also take care of platform differences in render texture coordinates.

Function:	Description:
float4 ComputeScreenPos (float4 clipPos)	Computes texture coordinate for doing a screenspace-mapped texture sample. Input is clip space position.
float4 ComputeGrabScreenPos (float4 clipPos)	Computes texture coordinate for sampling a GrabPass texure. Input is clip space position.

Vertex-lit helper functions in UnityCG.cginc

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

Function:	Description:
float3 ShadeVertexLights (float4 vertex, float3 normal)	Computes illumination from four per-vertex lights and ambient, given object space position & normal.