Microsoft DirectX 8.1 (pixel shader versions 1.2 and 1.3) |
texdp3tex
Performs a three-component dot product and uses the result to do a 1-D texture lookup.
texdp3tex dest, src
Registers
Argument | Description | Registers | Version | |||
---|---|---|---|---|---|---|
vn | cn | tn | rn | |||
dest | Destination register | x | 1.2, 1.3 | |||
src | Source register | x | 1.2, 1.3 |
Remarks
Texture registers must use the following sequence.
tex t(n) // Define tn as a standard 3-vector (tn must be // defined in some way before texdp3tex uses it). texdp3tex t(m), t(n) // where m > n. // Perform a three-component dot product between t(n) and // the texture coordinate set m. Use the scalar result to // do a 1-D texture lookup at texturestage m and place // the result in t(m).
Here is more detail about how the dot product and texture lookup are done.
// The texdp3tex instruction performs a three-component dot product. u' = TextureCoordinates(stage m)UVW • t(n)RGB // The result is used to sample the texture at texture stage m by performing // a 1-D lookup. t(m)RGBA = TextureSample(stage m)RGBA using (u',0,0) as coordinates.