texdp3tex (Pixel Shader)

Performs a three-component dot product and uses the result to do a 1-D texture lookup.

Syntax

texdp3tex (Pixel Shader) dest, src

Registers

dest

Destination register.

src

Input source register.

Remarks

Pixel shader versions	1_1	1_2	1_3	1_4	2_0	2_x	2_sw	3_0	3_sw
texdp3tex		x	x

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.

Instruction Information

Minimum operating systems	Windows 98