# m4x3 - vs

Multiplies a 4-component vector by a 4x3 matrix.

## Syntax

m4x3 dst, src0, src1 |
---|

where

- dst is the destination register. Result is a 3-component vector.
- src0 is a source register representing a 4-component vector.
- src1 is a source register representing a 4x3 matrix, which corresponds to the first of 3 consecutive registers.

## Remarks

Vertex shader versions | 1_1 | 2_0 | 2_x | 2_sw | 3_0 | 3_sw |
---|---|---|---|---|---|---|

m4x3 | x | x | x | x | x | x |

The xyz mask is required for the destination register. Negate and swizzle modifiers are allowed for src0, but not for src1.

The following code fragment 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);
```

The input vector is in register src0. The input 4x3 matrix is in register src1, and the next two higher registers, as shown in the expansion below. A 3D result is produced, leaving the other element of the destination register (dest.w) unaffected.

This operation is commonly used for transforming a position vector by a matrix that has no projective effect, such as occurs in model-space transformations. This instruction is implemented as a pair of dot products as shown below.

```
m4x3 r0.xyz, r1, c0 will be expanded to:
dp4 r0.x, r1, c0
dp4 r0.y, r1, c1
dp4 r0.z, r1, c2
```

Swizzle and negate modifiers are invalid for the src1 register. The dst and src0 register cannot be the same.

## Related topics