matrix3x4_t

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matrix3x4_t represents a matrix: a mathematical construct that allows Vectors to be transformed.

Matrices are chiefly used to rotate vectors, since vector addition and multiplication respectively take care of translation and scaling. A single matrix can store a transformation in all three modes however, making it powerful in calculation-heavy areas like vertex rendering and 3D view set-up.

Usage

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

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, and instead it 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().

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 MatrixMultiply(matrix3x4_t in1, matrix3x4_t in2, matrix3x4_t out)
Combines two matrices into one.
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).

See also