# matrix3x4_t

** matrix3x4_t** is a C++ class that represents a matrix: a mathematical construct that allows Vectors to be transformed.

Matrices are chiefly used to rotate vectors, since translation and scaling are taken care of by vector addition and multiplication respectively. A single matrix can store a transformation in all three modes however, making them useful in transformation-intense operations like vertex rendering and 3D view set-up.

**To do: **What is `VMatrix`

, and what relationship does it have to this class?

## Functions

### Generation

Matrix generation is best left to Source's pre-existing functions:

```
void AngleMatrix( QAngle angle, matrix_3x4_t& out ); // Rotation; can also use Quaternions or Radians
void PositionMatrix( Vector position, matrix3x4_t& out ); // Translation
void AngleMatrix( QAngle angle, Vector position, matrix3x4_t& out ); // Rotation + translation
void SetScaleMatrix( float scale, matrix3x4_t& out ); // Scale
```

Use `MatrixMultiply()`

to combine two matrices into one. You can do this any number of times.

### Application

**Tip:**Unless re-using an existing matrix you are better off rotating a vector with

`VectorRotate()`

, which accepts angles directly.The mathematical notation for a matrix transformation is (vector * matrix). Source does not support that syntax, though it would be trivial to add if you so wanted, and instead offers these functions:

```
void VectorTransform( Vector in1, matrix3x4_t in2, Vector& out );
void VectorITransform( Vector in1, matrix3x4_t in2, Vector& out ); // 'Inverse' of the above
```

There is an overload of `VectorRotate()`

that accepts a `matrix3x4_t`

. It seems to behave in the same way as `VectorTransform()`

.

### Other / utility

`void MatrixAngles()`

`void MatrixPosition()`

`void MatrixVectors()`

- Extract angles and vectors from a matrix.
`MatrixAngles()`

has many overloads. There is no way to extract a scale. `void MatrixTranspose()`

- Transposes a matrix.
**To do:**What this is good for. `void MatrixInvert()`

- Reverses a matrix, making it transform in the opposite direction(s). You could also use
`VectorITransform()`

to apply the matrix. `bool MatricesAreEqual()`

- Instead of (matrix1 == matrix2).
`void MatrixCopy()`

**Confirm:**Instead of (matrix1 = matrix2).