Accessing shader properties in Cg
Shader declares it's properties in a Properties block. If you want to access some of those properties in a Cg shader program, you need to declare a Cg variable with the same name and a matching type. An example is provided in Shader Tutorial: Vertex and Fragment Programs.
For example these shader properties:
_MyColor ("Some Color", Color) = (1,1,1,1)
_MyVector ("Some Vector", Vector) = (0,0,0,0)
_MyFloat ("My float", Float) = 0.5
_MyTexture ("Texture", 2D) = "white" {}
_MyCubemap ("Cubemap", CUBE) = "" {}
would be declared for access in Cg code as:
float4 _MyColor; float4 _MyVector; float _MyFloat; sampler2D _MyTexture; samplerCUBE _MyCubemap;
Cg can also accept uniform keyword, but it is not necessary:
uniform float4 _MyColor;
Property types in ShaderLab map to Cg variable types this way:
- Color and Vector properties map to float4 variables.
- Range and Float properties map to float variables.
- Texture properties map to sampler2D variables for regular (2D) textures. CUBE and RECT textures map to samplerCUBE and samplerRECT variables respectively.