# Matrix3

A class representing a 3x3 matrix.

## Example

``` var m = new Matrix3(); ```

## A Note on Row-Major and Column-Major Ordering

The set() method takes arguments in row-major order, while internally they are stored in the elements array in column-major order.

This means that calling ``` m.set(11, 12, 13, 21, 22, 23, 31, 32, 33); ``` will result in the elements array containing: ``` m.elements = [11, 21, 31, 12, 22, 32, 13, 23, 33]; ``` and internally all calculations are performed using column-major ordering. However, as the actual ordering makes no difference mathematically and most people are used to thinking about matrices in row-major order, the Verge3D documentation shows matrices in row-major order. Just bear in mind that if you are reading the source code, you'll have to take the transpose of any matrices outlined here to make sense of the calculations.

## Constructor

### Matrix3()

Creates and initializes the Matrix3 to the 3x3 identity matrix.

## Properties

### # .elements : Array

A column-major list of matrix values.

## Methods

### # .clone () : Matrix3

Creates a new Matrix3 and with identical elements to this one.

### # .copy (m : Matrix3) : this

Copies the elements of matrix m into this matrix.

### # .determinant () : Float

Computes and returns the determinant of this matrix.

### # .equals (m : Matrix3) : Boolean

Return true if this matrix and m are equal.

### # .fromArray (array : Array, offset : Integer) : this

array - the array to read the elements from.
offset - (optional) index of first element in the array. Default is 0.

Sets the elements of this matrix based on an array in column-major format.

### # .getInverse (m : Matrix3, throwOnDegenerate : Boolean) : this

m - the matrix to take the inverse of.
throwOnDegenerate - (optional) If true, throw an error if the matrix is degenerate (not invertible).

Set this matrix to the inverse of the passed matrix m, using the analytic method. If throwOnDegenerate is not set and the matrix is not invertible, set this to the 3x3 identity matrix.

### # .getNormalMatrix (m : Matrix4) : this

m - Matrix4

Sets this matrix as the upper left 3x3 of the normal matrix of the passed matrix4. The normal matrix is the inverse transpose of the matrix m.

### # .identity () : this

Resets this matrix to the 3x3 identity matrix: ``` 1, 0, 0 0, 1, 0 0, 0, 1 ```

### # .multiply (m : Matrix3) : this

Post-multiplies this matrix by m.

### # .multiplyMatrices (a : Matrix3, b : Matrix3) : this

Sets this matrix to a x b.

### # .multiplyScalar (s : Float) : this

Multiplies every component of the matrix by the scalar value s.

### # .set (n11 : Float, n12 : Float, n13 : Float, n21 : Float, n22 : Float, n23 : Float, n31 : Float, n32 : Float, n33 : Float) : this

n11 - value to put in row 1, col 1.
n12 - value to put in row 1, col 2.
...
...
n32 - value to put in row 3, col 2.
n33 - value to put in row 3, col 3.

Sets the 3x3 matrix values to the given row-major sequence of values.

### # .premultiply (m : Matrix3) : this

Pre-multiplies this matrix by m.

### # .setFromMatrix4 (m : Matrix4) : this

Set this matrx to the upper 3x3 matrix of the Matrix4 m.

### # .setUvTransform (tx : Float, ty : Float, sx : Float, sy : Float, rotation : Float, cx : Float, cy : Float) : this

tx - offset x
ty - offset y
sx - repeat x
sy - repeat y
cx - center x of rotation
cy - center y of rotation

Sets the UV transform matrix from offset, repeat, rotation, and center.

### # .toArray (array : Array, offset : Integer) : Array

array - (optional) array to store the resulting vector in. If not given a new array will be created.
offset - (optional) offset in the array at which to put the result.

Writes the elements of this matrix to an array in column-major format.

### # .transpose () : this

Transposes this matrix in place.

### # .transposeIntoArray (array : Array) : this

array - array to store the resulting vector in.

Transposes this matrix into the supplied array, and returns itself unchanged.