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pixi.js / src / core / math / Matrix.js
@Chad Engler Chad Engler on 22 May 2015 7 KB add out param to Matrix#toArray
var Point = require('./Point');

/**
 * The pixi Matrix class as an object, which makes it a lot faster,
 * here is a representation of it :
 * | a | b | tx|
 * | c | d | ty|
 * | 0 | 0 | 1 |
 *
 * @class
 * @memberof PIXI
 */
function Matrix()
{
    /**
     * @member {number}
     * @default 1
     */
    this.a = 1;

    /**
     * @member {number}
     * @default 0
     */
    this.b = 0;

    /**
     * @member {number}
     * @default 0
     */
    this.c = 0;

    /**
     * @member {number}
     * @default 1
     */
    this.d = 1;

    /**
     * @member {number}
     * @default 0
     */
    this.tx = 0;

    /**
     * @member {number}
     * @default 0
     */
    this.ty = 0;
}

Matrix.prototype.constructor = Matrix;
module.exports = Matrix;

/**
 * Creates a Matrix object based on the given array. The Element to Matrix mapping order is as follows:
 *
 * a = array[0]
 * b = array[1]
 * c = array[3]
 * d = array[4]
 * tx = array[2]
 * ty = array[5]
 *
 * @param array {number[]} The array that the matrix will be populated from.
 */
Matrix.prototype.fromArray = function (array)
{
    this.a = array[0];
    this.b = array[1];
    this.c = array[3];
    this.d = array[4];
    this.tx = array[2];
    this.ty = array[5];
};

/**
 * Creates an array from the current Matrix object.
 *
 * @param transpose {boolean} Whether we need to transpose the matrix or not
 * @return {number[]} the newly created array which contains the matrix
 */
Matrix.prototype.toArray = function (transpose, out)
{
    if (!this.array)
    {
        this.array = new Float32Array(9);
    }

    var array = out || this.array;

    if (transpose)
    {
        array[0] = this.a;
        array[1] = this.b;
        array[2] = 0;
        array[3] = this.c;
        array[4] = this.d;
        array[5] = 0;
        array[6] = this.tx;
        array[7] = this.ty;
        array[8] = 1;
    }
    else
    {
        array[0] = this.a;
        array[1] = this.c;
        array[2] = this.tx;
        array[3] = this.b;
        array[4] = this.d;
        array[5] = this.ty;
        array[6] = 0;
        array[7] = 0;
        array[8] = 1;
    }

    return array;
};

/**
 * Get a new position with the current transformation applied.
 * Can be used to go from a child's coordinate space to the world coordinate space. (e.g. rendering)
 *
 * @param pos {Point} The origin
 * @param [newPos] {Point} The point that the new position is assigned to (allowed to be same as input)
 * @return {Point} The new point, transformed through this matrix
 */
Matrix.prototype.apply = function (pos, newPos)
{
    newPos = newPos || new Point();

    var x = pos.x;
    var y = pos.y;

    newPos.x = this.a * x + this.c * y + this.tx;
    newPos.y = this.b * x + this.d * y + this.ty;

    return newPos;
};

/**
 * Get a new position with the inverse of the current transformation applied.
 * Can be used to go from the world coordinate space to a child's coordinate space. (e.g. input)
 *
 * @param pos {Point} The origin
 * @param [newPos] {Point} The point that the new position is assigned to (allowed to be same as input)
 * @return {Point} The new point, inverse-transformed through this matrix
 */
Matrix.prototype.applyInverse = function (pos, newPos)
{
    newPos = newPos || new Point();

    var id = 1 / (this.a * this.d + this.c * -this.b);

    var x = pos.x;
    var y = pos.y;

    newPos.x = this.d * id * x + -this.c * id * y + (this.ty * this.c - this.tx * this.d) * id;
    newPos.y = this.a * id * y + -this.b * id * x + (-this.ty * this.a + this.tx * this.b) * id;

    return newPos;
};

/**
 * Translates the matrix on the x and y.
 *
 * @param {number} x
 * @param {number} y
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.translate = function (x, y)
{
    this.tx += x;
    this.ty += y;

    return this;
};

/**
 * Applies a scale transformation to the matrix.
 *
 * @param {number} x The amount to scale horizontally
 * @param {number} y The amount to scale vertically
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.scale = function (x, y)
{
    this.a *= x;
    this.d *= y;
    this.c *= x;
    this.b *= y;
    this.tx *= x;
    this.ty *= y;

    return this;
};


/**
 * Applies a rotation transformation to the matrix.
 *
 * @param {number} angle - The angle in radians.
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.rotate = function (angle)
{
    var cos = Math.cos( angle );
    var sin = Math.sin( angle );

    var a1 = this.a;
    var c1 = this.c;
    var tx1 = this.tx;

    this.a = a1 * cos-this.b * sin;
    this.b = a1 * sin+this.b * cos;
    this.c = c1 * cos-this.d * sin;
    this.d = c1 * sin+this.d * cos;
    this.tx = tx1 * cos - this.ty * sin;
    this.ty = tx1 * sin + this.ty * cos;

    return this;
};

/**
 * Appends the given Matrix to this Matrix.
 *
 * @param {Matrix} matrix
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.append = function (matrix)
{
    var a1 = this.a;
    var b1 = this.b;
    var c1 = this.c;
    var d1 = this.d;

    this.a  = matrix.a * a1 + matrix.b * c1;
    this.b  = matrix.a * b1 + matrix.b * d1;
    this.c  = matrix.c * a1 + matrix.d * c1;
    this.d  = matrix.c * b1 + matrix.d * d1;

    this.tx = matrix.tx * a1 + matrix.ty * c1 + this.tx;
    this.ty = matrix.tx * b1 + matrix.ty * d1 + this.ty;

    return this;
};

/**
 * Prepends the given Matrix to this Matrix.
 *
 * @param {Matrix} matrix
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.prepend = function(matrix)
{
    var tx1 = this.tx;

    if (matrix.a !== 1 || matrix.b !== 0 || matrix.c !== 0 || matrix.d !== 1)
    {
        var a1 = this.a;
        var c1 = this.c;
        this.a  = a1*matrix.a+this.b*matrix.c;
        this.b  = a1*matrix.b+this.b*matrix.d;
        this.c  = c1*matrix.a+this.d*matrix.c;
        this.d  = c1*matrix.b+this.d*matrix.d;
    }

    this.tx = tx1*matrix.a+this.ty*matrix.c+matrix.tx;
    this.ty = tx1*matrix.b+this.ty*matrix.d+matrix.ty;

    return this;
};

/**
 * Inverts this matrix
 *
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.invert = function()
{
    var a1 = this.a;
    var b1 = this.b;
    var c1 = this.c;
    var d1 = this.d;
    var tx1 = this.tx;
    var n = a1*d1-b1*c1;

    this.a = d1/n;
    this.b = -b1/n;
    this.c = -c1/n;
    this.d = a1/n;
    this.tx = (c1*this.ty-d1*tx1)/n;
    this.ty = -(a1*this.ty-b1*tx1)/n;

    return this;
};


/**
 * Resets this Matix to an identity (default) matrix.
 *
 * @return {Matrix} This matrix. Good for chaining method calls.
 */
Matrix.prototype.identity = function ()
{
    this.a = 1;
    this.b = 0;
    this.c = 0;
    this.d = 1;
    this.tx = 0;
    this.ty = 0;

    return this;
};

/**
 * Creates a new Matrix object with the same values as this one.
 *
 * @return {Matrix} A copy of this matrix. Good for chaining method calls.
 */
Matrix.prototype.clone = function ()
{
    var matrix = new Matrix();
    matrix.a = this.a;
    matrix.b = this.b;
    matrix.c = this.c;
    matrix.d = this.d;
    matrix.tx = this.tx;
    matrix.ty = this.ty;

    return matrix;
};

/**
 * Changes the values of the given matrix to be the same as the ones in this matrix
 *
 * @return {Matrix} The matrix given in parameter with its values updated.
 */
Matrix.prototype.copy = function (matrix)
{
    matrix.a = this.a;
    matrix.b = this.b;
    matrix.c = this.c;
    matrix.d = this.d;
    matrix.tx = this.tx;
    matrix.ty = this.ty;

    return matrix;
};

/**
 * A default (identity) matrix
 */
Matrix.IDENTITY = new Matrix();
/**
 * A temp matrix
 */
Matrix.TEMP_MATRIX = new Matrix();