ShaderLab builtin values

Unity provides a handful of builtin values for your shaders: things like current object's transformation matrices, time etc.

You just use them in ShaderLab like you'd use any other property, the only difference is that you don't have to declare it somewhere - they are "built in".

Using them in programmable shaders requires including UnityCG.cginc file.

Transformations

float4x4 UNITY_MATRIX_MVP

Current model*view*projection matrix

float4x4 UNITY_MATRIX_MV

Current model*view matrix

float4x4 UNITY_MATRIX_P

Current projection matrix

float4x4 UNITY_MATRIX_T_MV

Transpose of model*view matrix

float4x4 UNITY_MATRIX_IT_MV

Inverse transpose of model*view matrix

float4x4 UNITY_MATRIX_TEXTURE0 to UNITY_MATRIX_TEXTURE3

Texture transformation matrices

float4x4 _Object2World

Current model matrix

float4x4 _World2Object

Inverse of current world matrix

float3 _WorldSpaceCameraPos

World space position of the camera

float4 unity_Scale

xyz components unused; .w contains scale for uniformly scaled objects.

Lighting

In plain ShaderLab, you access the following properties by appending zero at the end: e.g. the light's model*light color is _ModelLightColor0. In Cg shaders, they are exposed as arrays with a single element, so the same in Cg is _ModelLightColor[0].

Name	Type	Value
_ModelLightColor	float4	Material's Main * Light color
_SpecularLightColor	float4	Material's Specular * Light color
_ObjectSpaceLightPos	float4	Light's position in object space. w component is 0 for directional lights, 1 for other lights
_Light2World	float4x4	Light to World space matrix
_World2Light	float4x4	World to Light space matrix
_Object2Light	float4x4	Object to Light space matrix

Various

• float4 _Time : Time (t/20, t, t*2, t*3), use to animate things inside the shaders
• float4 _SinTime : Sine of time: (t/8, t/4, t/2, t)
• float4 _CosTime : Cosine of time: (t/8, t/4, t/2, t)
• float4 _ProjectionParams :
  x is 1.0 or -1.0, negative if currently rendering with a flipped projection matrix
  y is camera's near plane
  z is camera's far plane
  w is 1/FarPlane.
• float4 _ScreenParams :
  x is current render target width in pixels
  y is current render target height in pixels
  z is 1.0 + 1.0/width
  w is 1.0 + 1.0/height

Page last updated: 2012-09-04