m4x4 - ps

Multiplies a 4-component vector by a 4x4 matrix.


m4x4 dst, src0, src1



  • dst is the destination register. Result is a 4-component vector.
  • src0 is a source register representing a 4-component vector.
  • src1 is a source register representing a 4x4 matrix, which corresponds to the first of 4 consecutive registers.


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

Pixel Shader Instructions