Microsoft DirectX 8.0 (C++)

Setting Pixel Shader Texture Inputs

There is a direct mapping between the input register colors and the texture stages. The temporary registers of the Direct3DX pixel shader assembler are preloaded with the texture colors from the corresponding texture stages. Conversely, the textures are bound directly to the temporary registers by calling the IDirect3DDevice8::SetTexture method.

In addition, texture coordinates are mapped directly and defined by texture declarations.