Microsoft DirectX 8.0 (C++)

Output Registers

Output registers are defined as the inputs to the rasterizer. Generated data is written into the output register file, which has write-only access.

The output registers are defined by the register model of the raster shader, which must support the following minimum counts.

Name I/O Permissions Count
oDn write-only 2 4-D vectors
oFog write-only 1 scalar float
oPos write-only 1 4-D vector
oPts write-only 1 scalar float
oTn write-only 4 4-D vectors

Write operations to destination registers not indicated above are ignored.

Register names are preceded by a lower case 'o,' indicating that the output registers are write-only.

When using vertex shaders with an implementation supporting only the Microsoft® DirectX® 6.0 or 7.0 pixel processing model—that is, an implementation without pixels shaders—the following output registers are available.

Name I/0 Permissions Count Description
oDn write-only 2 vectors Output color data. Required for diffuse color and specular color.
oPos write-only 1 vector Output position. Required for clipping.
oTn write-only 2 vectors Output texture coordinates. Required for maximum number of textures that can be simultaneously bound to the texture blending stages.