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Computes the product of a 4-component vector and a 4x4 matrix.
| m4x4 dst, src0, src1 |
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where
| Pixel shader versions | 1_1 | 1_2 | 1_3 | 1_4 | 2_0 | 2_x | 2_sw | 3_0 | 3_sw |
|---|---|---|---|---|---|---|---|---|---|
| m4x4 | x | x | x | x | x |
The xyzw (default) mask is required for the destination register. Negate and swizzle modifiers are allowed for src0, but not for src1.
Swizzle and negate modifiers are invalid for the src0 register. The dst and src0 registers cannot be the same.
The following code snippet shows the operations performed.
dest.x = (src0.x*src1.x) + (src0.y*src1.y) + (src0.z*src1.z) + (src0.w*src1.w); dest.y = (src0.x*src2.x) + (src0.y*src2.y) + (src0.z*src2.z) + (src0.w*src2.w); dest.z = (src0.x*src3.x) + (src0.y*src3.y) + (src0.z*src3.z) + (src0.w*src3.w); dest.w = (src0.x*src4.x) + (src0.y*src4.y) + (src0.z*src4.z) + (src0.w*src4.w);
The input vector is in register src0. The input 4x4 matrix is in register src1, and the next three higher registers, as shown in the expansion below.
This operation is commonly used for transforming a position by a projection matrix. This instruction is implemented as a set of dot products as shown here.
m4x4 r0.xyzw, r1, c0 will be expanded to: dp4 r0.x, r1, c0 dp4 r0.y, r1, c1 dp4 r0.z, r1, c2 dp4 r0.w, r1, c3