# Source: mat2d.js

``````import * as glMatrix from "./common.js";

/**
* 2x3 Matrix
* @module mat2d
* @description
* A mat2d contains six elements defined as:
* <pre>
* [a, b,
*  c, d,
*  tx, ty]
* </pre>
* This is a short form for the 3x3 matrix:
* <pre>
* [a, b, 0,
*  c, d, 0,
*  tx, ty, 1]
* </pre>
* The last column is ignored so the array is shorter and operations are faster.
*/

/**
* Creates a new identity mat2d
*
* @returns {mat2d} a new 2x3 matrix
*/
export function create() {
let out = new glMatrix.ARRAY_TYPE(6);
if (glMatrix.ARRAY_TYPE != Float32Array) {
out[1] = 0;
out[2] = 0;
out[4] = 0;
out[5] = 0;
}
out[0] = 1;
out[3] = 1;
return out;
}

/**
* Creates a new mat2d initialized with values from an existing matrix
*
* @param {ReadonlyMat2d} a matrix to clone
* @returns {mat2d} a new 2x3 matrix
*/
export function clone(a) {
let out = new glMatrix.ARRAY_TYPE(6);
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
out[4] = a[4];
out[5] = a[5];
return out;
}

/**
* Copy the values from one mat2d to another
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the source matrix
* @returns {mat2d} out
*/
export function copy(out, a) {
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
out[4] = a[4];
out[5] = a[5];
return out;
}

/**
* Set a mat2d to the identity matrix
*
* @param {mat2d} out the receiving matrix
* @returns {mat2d} out
*/
export function identity(out) {
out[0] = 1;
out[1] = 0;
out[2] = 0;
out[3] = 1;
out[4] = 0;
out[5] = 0;
return out;
}

/**
* Create a new mat2d with the given values
*
* @param {Number} a Component A (index 0)
* @param {Number} b Component B (index 1)
* @param {Number} c Component C (index 2)
* @param {Number} d Component D (index 3)
* @param {Number} tx Component TX (index 4)
* @param {Number} ty Component TY (index 5)
* @returns {mat2d} A new mat2d
*/
export function fromValues(a, b, c, d, tx, ty) {
let out = new glMatrix.ARRAY_TYPE(6);
out[0] = a;
out[1] = b;
out[2] = c;
out[3] = d;
out[4] = tx;
out[5] = ty;
return out;
}

/**
* Set the components of a mat2d to the given values
*
* @param {mat2d} out the receiving matrix
* @param {Number} a Component A (index 0)
* @param {Number} b Component B (index 1)
* @param {Number} c Component C (index 2)
* @param {Number} d Component D (index 3)
* @param {Number} tx Component TX (index 4)
* @param {Number} ty Component TY (index 5)
* @returns {mat2d} out
*/
export function set(out, a, b, c, d, tx, ty) {
out[0] = a;
out[1] = b;
out[2] = c;
out[3] = d;
out[4] = tx;
out[5] = ty;
return out;
}

/**
* Inverts a mat2d
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the source matrix
* @returns {mat2d} out
*/
export function invert(out, a) {
let aa = a[0],
ab = a[1],
ac = a[2],
let atx = a[4],
aty = a[5];

let det = aa * ad - ab * ac;
if (!det) {
return null;
}
det = 1.0 / det;

out[0] = ad * det;
out[1] = -ab * det;
out[2] = -ac * det;
out[3] = aa * det;
out[4] = (ac * aty - ad * atx) * det;
out[5] = (ab * atx - aa * aty) * det;
return out;
}

/**
* Calculates the determinant of a mat2d
*
* @param {ReadonlyMat2d} a the source matrix
* @returns {Number} determinant of a
*/
export function determinant(a) {
return a[0] * a[3] - a[1] * a[2];
}

/**
* Multiplies two mat2d's
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the first operand
* @param {ReadonlyMat2d} b the second operand
* @returns {mat2d} out
*/
export function multiply(out, a, b) {
let a0 = a[0],
a1 = a[1],
a2 = a[2],
a3 = a[3],
a4 = a[4],
a5 = a[5];
let b0 = b[0],
b1 = b[1],
b2 = b[2],
b3 = b[3],
b4 = b[4],
b5 = b[5];
out[0] = a0 * b0 + a2 * b1;
out[1] = a1 * b0 + a3 * b1;
out[2] = a0 * b2 + a2 * b3;
out[3] = a1 * b2 + a3 * b3;
out[4] = a0 * b4 + a2 * b5 + a4;
out[5] = a1 * b4 + a3 * b5 + a5;
return out;
}

/**
* Rotates a mat2d by the given angle
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the matrix to rotate
* @param {Number} rad the angle to rotate the matrix by
* @returns {mat2d} out
*/
export function rotate(out, a, rad) {
let a0 = a[0],
a1 = a[1],
a2 = a[2],
a3 = a[3],
a4 = a[4],
a5 = a[5];
let s = Math.sin(rad);
let c = Math.cos(rad);
out[0] = a0 * c + a2 * s;
out[1] = a1 * c + a3 * s;
out[2] = a0 * -s + a2 * c;
out[3] = a1 * -s + a3 * c;
out[4] = a4;
out[5] = a5;
return out;
}

/**
* Scales the mat2d by the dimensions in the given vec2
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the matrix to translate
* @param {ReadonlyVec2} v the vec2 to scale the matrix by
* @returns {mat2d} out
**/
export function scale(out, a, v) {
let a0 = a[0],
a1 = a[1],
a2 = a[2],
a3 = a[3],
a4 = a[4],
a5 = a[5];
let v0 = v[0],
v1 = v[1];
out[0] = a0 * v0;
out[1] = a1 * v0;
out[2] = a2 * v1;
out[3] = a3 * v1;
out[4] = a4;
out[5] = a5;
return out;
}

/**
* Translates the mat2d by the dimensions in the given vec2
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the matrix to translate
* @param {ReadonlyVec2} v the vec2 to translate the matrix by
* @returns {mat2d} out
**/
export function translate(out, a, v) {
let a0 = a[0],
a1 = a[1],
a2 = a[2],
a3 = a[3],
a4 = a[4],
a5 = a[5];
let v0 = v[0],
v1 = v[1];
out[0] = a0;
out[1] = a1;
out[2] = a2;
out[3] = a3;
out[4] = a0 * v0 + a2 * v1 + a4;
out[5] = a1 * v0 + a3 * v1 + a5;
return out;
}

/**
* Creates a matrix from a given angle
* This is equivalent to (but much faster than):
*
*     mat2d.identity(dest);
*     mat2d.rotate(dest, dest, rad);
*
* @param {mat2d} out mat2d receiving operation result
* @param {Number} rad the angle to rotate the matrix by
* @returns {mat2d} out
*/
export function fromRotation(out, rad) {
let s = Math.sin(rad),
out[0] = c;
out[1] = s;
out[2] = -s;
out[3] = c;
out[4] = 0;
out[5] = 0;
return out;
}

/**
* Creates a matrix from a vector scaling
* This is equivalent to (but much faster than):
*
*     mat2d.identity(dest);
*     mat2d.scale(dest, dest, vec);
*
* @param {mat2d} out mat2d receiving operation result
* @param {ReadonlyVec2} v Scaling vector
* @returns {mat2d} out
*/
export function fromScaling(out, v) {
out[0] = v[0];
out[1] = 0;
out[2] = 0;
out[3] = v[1];
out[4] = 0;
out[5] = 0;
return out;
}

/**
* Creates a matrix from a vector translation
* This is equivalent to (but much faster than):
*
*     mat2d.identity(dest);
*     mat2d.translate(dest, dest, vec);
*
* @param {mat2d} out mat2d receiving operation result
* @param {ReadonlyVec2} v Translation vector
* @returns {mat2d} out
*/
export function fromTranslation(out, v) {
out[0] = 1;
out[1] = 0;
out[2] = 0;
out[3] = 1;
out[4] = v[0];
out[5] = v[1];
return out;
}

/**
* Returns a string representation of a mat2d
*
* @param {ReadonlyMat2d} a matrix to represent as a string
* @returns {String} string representation of the matrix
*/
export function str(a) {
return (
"mat2d(" +
a[0] +
", " +
a[1] +
", " +
a[2] +
", " +
a[3] +
", " +
a[4] +
", " +
a[5] +
")"
);
}

/**
* Returns Frobenius norm of a mat2d
*
* @param {ReadonlyMat2d} a the matrix to calculate Frobenius norm of
* @returns {Number} Frobenius norm
*/
export function frob(a) {
return Math.hypot(a[0], a[1], a[2], a[3], a[4], a[5], 1);
}

/**
* Adds two mat2d's
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the first operand
* @param {ReadonlyMat2d} b the second operand
* @returns {mat2d} out
*/
export function add(out, a, b) {
out[0] = a[0] + b[0];
out[1] = a[1] + b[1];
out[2] = a[2] + b[2];
out[3] = a[3] + b[3];
out[4] = a[4] + b[4];
out[5] = a[5] + b[5];
return out;
}

/**
* Subtracts matrix b from matrix a
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the first operand
* @param {ReadonlyMat2d} b the second operand
* @returns {mat2d} out
*/
export function subtract(out, a, b) {
out[0] = a[0] - b[0];
out[1] = a[1] - b[1];
out[2] = a[2] - b[2];
out[3] = a[3] - b[3];
out[4] = a[4] - b[4];
out[5] = a[5] - b[5];
return out;
}

/**
* Multiply each element of the matrix by a scalar.
*
* @param {mat2d} out the receiving matrix
* @param {ReadonlyMat2d} a the matrix to scale
* @param {Number} b amount to scale the matrix's elements by
* @returns {mat2d} out
*/
export function multiplyScalar(out, a, b) {
out[0] = a[0] * b;
out[1] = a[1] * b;
out[2] = a[2] * b;
out[3] = a[3] * b;
out[4] = a[4] * b;
out[5] = a[5] * b;
return out;
}

/**
* Adds two mat2d's after multiplying each element of the second operand by a scalar value.
*
* @param {mat2d} out the receiving vector
* @param {ReadonlyMat2d} a the first operand
* @param {ReadonlyMat2d} b the second operand
* @param {Number} scale the amount to scale b's elements by before adding
* @returns {mat2d} out
*/
export function multiplyScalarAndAdd(out, a, b, scale) {
out[0] = a[0] + b[0] * scale;
out[1] = a[1] + b[1] * scale;
out[2] = a[2] + b[2] * scale;
out[3] = a[3] + b[3] * scale;
out[4] = a[4] + b[4] * scale;
out[5] = a[5] + b[5] * scale;
return out;
}

/**
* Returns whether or not the matrices have exactly the same elements in the same position (when compared with ===)
*
* @param {ReadonlyMat2d} a The first matrix.
* @param {ReadonlyMat2d} b The second matrix.
* @returns {Boolean} True if the matrices are equal, false otherwise.
*/
export function exactEquals(a, b) {
return (
a[0] === b[0] &&
a[1] === b[1] &&
a[2] === b[2] &&
a[3] === b[3] &&
a[4] === b[4] &&
a[5] === b[5]
);
}

/**
* Returns whether or not the matrices have approximately the same elements in the same position.
*
* @param {ReadonlyMat2d} a The first matrix.
* @param {ReadonlyMat2d} b The second matrix.
* @returns {Boolean} True if the matrices are equal, false otherwise.
*/
export function equals(a, b) {
let a0 = a[0],
a1 = a[1],
a2 = a[2],
a3 = a[3],
a4 = a[4],
a5 = a[5];
let b0 = b[0],
b1 = b[1],
b2 = b[2],
b3 = b[3],
b4 = b[4],
b5 = b[5];
return (
Math.abs(a0 - b0) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a0), Math.abs(b0)) &&
Math.abs(a1 - b1) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a1), Math.abs(b1)) &&
Math.abs(a2 - b2) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a2), Math.abs(b2)) &&
Math.abs(a3 - b3) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a3), Math.abs(b3)) &&
Math.abs(a4 - b4) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a4), Math.abs(b4)) &&
Math.abs(a5 - b5) <=
glMatrix.EPSILON * Math.max(1.0, Math.abs(a5), Math.abs(b5))
);
}

/**
* Alias for {@link mat2d.multiply}
* @function
*/
export const mul = multiply;

/**
* Alias for {@link mat2d.subtract}
* @function
*/
export const sub = subtract;
``````