dp4 (Pixel Shader)

Computes the four-component dot product of the source registers.

Syntax

dp4 dst, src0, src1

where

dst is the destination register.
src0 is a source register.
src1 is a source register.

Remarks

Pixel shader versions	1_1	1_2	1_3	1_4	2_0	2_x	2_sw	3_0	3_sw
dp4	x	x	x	x	x	x	x	x	x

The following code fragment shows the operations performed:

dest.w = (src0.x * src1.x) + (src0.y * src1.y) + 
         (src0.z * src1.z) + (src0.w * src1.w);
dest.x = dest.y = dest.z = unused;

In version 1_X, this instruction cannot be co-issued.

In version 1_X, this instruction does not automatically clamp the output result between zero and one. If clamping is necessary, use the Instruction Modifiers.

In version 1_X, this instruction runs in both the vector and alpha pipeline.

Limitations for versions 1_2 and 1_3:

Each shader can use up to a maximum of fourdp instructions.
Each dp4 instruction counts as two arithmetic instructions.

Instruction Information

Minimum operating system	Windows 98