The semantics can be used to access easily a variable that want to use, but some semantics can't be used because they are already defined. Next semantics are the list of semantics already defined.
(source: http://msdn.microsoft.com/en-us/library/bb509650(VS.85).aspx )
<Development shader system using semantics - 4.June, 06 by sonee>
Vertex Shader Semantics
These semantics have meaning when attached to a vertex-shader parameters. These semantics are supported in both Direct3D 9 and Direct3D 10.
| Input | Description | Type |
|---|---|---|
| BINORMAL[n] | Binormal | float4 |
| BLENDINDICES[n] | Blend indices | uint |
| BLENDWEIGHT[n] | Blend weights | float |
| COLOR[n] | Diffuse and specular color | float4 |
| NORMAL[n] | Normal vector | float4 |
| POSITION[n] | Vertex position in object space. | float4 |
| POSITIONT | Transformed vertex position. | float4 |
| PSIZE[n] | Point size | float |
| TANGENT[n] | Tangent | float4 |
| TEXCOORD[n] | Texture coordinates | float4 |
| Output | Description | Type |
| COLOR[n] | Diffuse or specular color | float4 |
| FOG | Vertex fog | float |
| POSITION[n] | Position of a vertex in homogenous space. Compute position in screen-space by dividing (x,y,z) by w. Every vertex shader must write out a parameter with this semantic. | float4 |
| PSIZE | Point size | float |
| TESSFACTOR[n] | Tessellation factor | float |
| TEXCOORD[n] | Texture coordinates | float4 |
n is an optional integer between 0 and the number of resources supported. For example, POSITION0, TEXCOOR1, etc.
Generally, the most programmers are using TEXCOORD[n] semantics to give pixel shader any parameters to present their special materials in Vertex Shader.
Pixel Shader Semantics
These semantics have meaning when attached to a pixel-shader input parameter. These semantics are supported in both Direct3D 9 and Direct3D 10.
| Input | Description | Type |
|---|---|---|
| COLOR[n] | Diffuse or specular color. | float4 |
| TEXCOORD[n] | Texture coordinates | float4 |
| VFACE | Floating-point scalar that indicates a back-facing primitive. A negative value faces backwards, while a positive value faces the camera. | float |
| VPOS | Contains the current pixel (x,y) location. | float2 |
| Output | Description | Type |
| COLOR[n] | Output color | float4 |
| DEPTH[n] | Output depth | float |
n is an optional integer between 0 and the number of resources supported. For example, PSIZE0, COLOR1, etc.
The COLOR semantic is only valid in shader compatibility mode (that is, when the shader is created using D3D10_SHADER_ENABLE_BACKWARDS_COMPATIBILITY).
