Vector2.js

/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2018 Photon Storm Ltd.
 * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
 */

//  Adapted from [gl-matrix](https://github.com/toji/gl-matrix) by toji
//  and [vecmath](https://github.com/mattdesl/vecmath) by mattdesl

var Class = require('../utils/Class');

/**
 * @typedef {object} Vector2Like
 *
 * @property {number} x - The x component.
 * @property {number} y - The y component.
 */

/**
 * @classdesc
 * A representation of a vector in 2D space.
 *
 * A two-component vector.
 *
 * @class Vector2
 * @memberOf Phaser.Math
 * @constructor
 * @since 3.0.0
 *
 * @param {number|Vector2Like} [x] - The x component, or an object with `x` and `y` properties.
 * @param {number} [y] - The y component.
 */
var Vector2 = new Class({

    initialize:

    function Vector2 (x, y)
    {
        /**
         * The x component of this Vector.
         *
         * @name Phaser.Math.Vector2#x
         * @type {number}
         * @default 0
         * @since 3.0.0
         */
        this.x = 0;

        /**
         * The y component of this Vector.
         *
         * @name Phaser.Math.Vector2#y
         * @type {number}
         * @default 0
         * @since 3.0.0
         */
        this.y = 0;

        if (typeof x === 'object')
        {
            this.x = x.x || 0;
            this.y = x.y || 0;
        }
        else
        {
            if (y === undefined) { y = x; }

            this.x = x || 0;
            this.y = y || 0;
        }
    },

    /**
     * Make a clone of this Vector2.
     *
     * @method Phaser.Math.Vector2#clone
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} A clone of this Vector2.
     */
    clone: function ()
    {
        return new Vector2(this.x, this.y);
    },

    /**
     * Copy the components of a given Vector into this Vector.
     *
     * @method Phaser.Math.Vector2#copy
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to copy the components from.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    copy: function (src)
    {
        this.x = src.x || 0;
        this.y = src.y || 0;

        return this;
    },

    /**
     * Set the component values of this Vector from a given Vector2Like object.
     *
     * @method Phaser.Math.Vector2#setFromObject
     * @since 3.0.0
     *
     * @param {Vector2Like} obj - The object containing the component values to set for this Vector.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    setFromObject: function (obj)
    {
        this.x = obj.x || 0;
        this.y = obj.y || 0;

        return this;
    },

    /**
     * Set the `x` and `y` components of the this Vector to the given `x` and `y` values.
     *
     * @method Phaser.Math.Vector2#set
     * @since 3.0.0
     *
     * @param {number} x - The x value to set for this Vector.
     * @param {number} [y=x] - The y value to set for this Vector.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    set: function (x, y)
    {
        if (y === undefined) { y = x; }

        this.x = x;
        this.y = y;

        return this;
    },

    /**
     * This method is an alias for `Vector2.set`.
     *
     * @method Phaser.Math.Vector2#setTo
     * @since 3.4.0
     *
     * @param {number} x - The x value to set for this Vector.
     * @param {number} [y=x] - The y value to set for this Vector.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    setTo: function (x, y)
    {
        return this.set(x, y);
    },

    /**
     * Sets the `x` and `y` values of this object from a given polar coordinate.
     *
     * @method Phaser.Math.Vector2#setToPolar
     * @since 3.0.0
     *
     * @param {number} azimuth - The angular coordinate, in radians.
     * @param {number} [radius=1] - The radial coordinate (length).
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    setToPolar: function (azimuth, radius)
    {
        if (radius == null) { radius = 1; }

        this.x = Math.cos(azimuth) * radius;
        this.y = Math.sin(azimuth) * radius;

        return this;
    },

    /**
     * Check whether this Vector is equal to a given Vector.
     *
     * Performs a strict equality check against each Vector's components.
     *
     * @method Phaser.Math.Vector2#equals
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} v - The vector to compare with this Vector.
     *
     * @return {boolean} Whether the given Vector is equal to this Vector.
     */
    equals: function (v)
    {
        return ((this.x === v.x) && (this.y === v.y));
    },

    /**
     * Calculate the angle between this Vector and the positive x-axis, in radians.
     *
     * @method Phaser.Math.Vector2#angle
     * @since 3.0.0
     *
     * @return {number} The angle between this Vector, and the positive x-axis, given in radians.
     */
    angle: function ()
    {
        // computes the angle in radians with respect to the positive x-axis

        var angle = Math.atan2(this.y, this.x);

        if (angle < 0)
        {
            angle += 2 * Math.PI;
        }

        return angle;
    },

    /**
     * Add a given Vector to this Vector. Addition is component-wise.
     *
     * @method Phaser.Math.Vector2#add
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to add to this Vector.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    add: function (src)
    {
        this.x += src.x;
        this.y += src.y;

        return this;
    },

    /**
     * Subtract the given Vector from this Vector. Subtraction is component-wise.
     *
     * @method Phaser.Math.Vector2#subtract
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to subtract from this Vector.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    subtract: function (src)
    {
        this.x -= src.x;
        this.y -= src.y;

        return this;
    },

    /**
     * Perform a component-wise multiplication between this Vector and the given Vector.
     *
     * Multiplies this Vector by the given Vector.
     *
     * @method Phaser.Math.Vector2#multiply
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to multiply this Vector by.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    multiply: function (src)
    {
        this.x *= src.x;
        this.y *= src.y;

        return this;
    },

    /**
     * Scale this Vector by the given value.
     *
     * @method Phaser.Math.Vector2#scale
     * @since 3.0.0
     *
     * @param {number} value - The value to scale this Vector by.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    scale: function (value)
    {
        if (isFinite(value))
        {
            this.x *= value;
            this.y *= value;
        }
        else
        {
            this.x = 0;
            this.y = 0;
        }

        return this;
    },

    /**
     * Perform a component-wise division between this Vector and the given Vector.
     *
     * Divides this Vector by the given Vector.
     *
     * @method Phaser.Math.Vector2#divide
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to divide this Vector by.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    divide: function (src)
    {
        this.x /= src.x;
        this.y /= src.y;

        return this;
    },

    /**
     * Negate the `x` and `y` components of this Vector.
     *
     * @method Phaser.Math.Vector2#negate
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    negate: function ()
    {
        this.x = -this.x;
        this.y = -this.y;

        return this;
    },

    /**
     * Calculate the distance between this Vector and the given Vector.
     *
     * @method Phaser.Math.Vector2#distance
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to calculate the distance to.
     *
     * @return {number} The distance from this Vector to the given Vector.
     */
    distance: function (src)
    {
        var dx = src.x - this.x;
        var dy = src.y - this.y;

        return Math.sqrt(dx * dx + dy * dy);
    },

    /**
     * Calculate the distance between this Vector and the given Vector, squared.
     *
     * @method Phaser.Math.Vector2#distanceSq
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector to calculate the distance to.
     *
     * @return {number} The distance from this Vector to the given Vector, squared.
     */
    distanceSq: function (src)
    {
        var dx = src.x - this.x;
        var dy = src.y - this.y;

        return dx * dx + dy * dy;
    },

    /**
     * Calculate the length (or magnitude) of this Vector.
     *
     * @method Phaser.Math.Vector2#length
     * @since 3.0.0
     *
     * @return {number} The length of this Vector.
     */
    length: function ()
    {
        var x = this.x;
        var y = this.y;

        return Math.sqrt(x * x + y * y);
    },

    /**
     * Calculate the length of this Vector squared.
     *
     * @method Phaser.Math.Vector2#lengthSq
     * @since 3.0.0
     *
     * @return {number} The length of this Vector, squared.
     */
    lengthSq: function ()
    {
        var x = this.x;
        var y = this.y;

        return x * x + y * y;
    },

    /**
     * Normalize this Vector.
     *
     * Makes the vector a unit length vector (magnitude of 1) in the same direction.
     *
     * @method Phaser.Math.Vector2#normalize
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    normalize: function ()
    {
        var x = this.x;
        var y = this.y;
        var len = x * x + y * y;

        if (len > 0)
        {
            len = 1 / Math.sqrt(len);

            this.x = x * len;
            this.y = y * len;
        }

        return this;
    },

    /**
     * Right-hand normalize (make unit length) this Vector.
     *
     * @method Phaser.Math.Vector2#normalizeRightHand
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    normalizeRightHand: function ()
    {
        var x = this.x;

        this.x = this.y * -1;
        this.y = x;

        return this;
    },

    /**
     * Calculate the dot product of this Vector and the given Vector.
     *
     * @method Phaser.Math.Vector2#dot
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector2 to dot product with this Vector2.
     *
     * @return {number} The dot product of this Vector and the given Vector.
     */
    dot: function (src)
    {
        return this.x * src.x + this.y * src.y;
    },

    /**
     * [description]
     *
     * @method Phaser.Math.Vector2#cross
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - [description]
     *
     * @return {number} [description]
     */
    cross: function (src)
    {
        return this.x * src.y - this.y * src.x;
    },

    /**
     * Linearly interpolate between this Vector and the given Vector.
     *
     * Interpolates this Vector towards the given Vector.
     *
     * @method Phaser.Math.Vector2#lerp
     * @since 3.0.0
     *
     * @param {Phaser.Math.Vector2} src - The Vector2 to interpolate towards.
     * @param {number} [t=0] - The interpolation percentage, between 0 and 1.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    lerp: function (src, t)
    {
        if (t === undefined) { t = 0; }

        var ax = this.x;
        var ay = this.y;

        this.x = ax + t * (src.x - ax);
        this.y = ay + t * (src.y - ay);

        return this;
    },

    /**
     * Transform this Vector with the given Matrix.
     *
     * @method Phaser.Math.Vector2#transformMat3
     * @since 3.0.0
     *
     * @param {Phaser.Math.Matrix3} mat - The Matrix3 to transform this Vector2 with.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    transformMat3: function (mat)
    {
        var x = this.x;
        var y = this.y;
        var m = mat.val;

        this.x = m[0] * x + m[3] * y + m[6];
        this.y = m[1] * x + m[4] * y + m[7];

        return this;
    },

    /**
     * Transform this Vector with the given Matrix.
     *
     * @method Phaser.Math.Vector2#transformMat4
     * @since 3.0.0
     *
     * @param {Phaser.Math.Matrix4} mat - The Matrix4 to transform this Vector2 with.
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    transformMat4: function (mat)
    {
        var x = this.x;
        var y = this.y;
        var m = mat.val;

        this.x = m[0] * x + m[4] * y + m[12];
        this.y = m[1] * x + m[5] * y + m[13];

        return this;
    },

    /**
     * Make this Vector the zero vector (0, 0).
     *
     * @method Phaser.Math.Vector2#reset
     * @since 3.0.0
     *
     * @return {Phaser.Math.Vector2} This Vector2.
     */
    reset: function ()
    {
        this.x = 0;
        this.y = 0;

        return this;
    }

});

/**
 * A static zero Vector2 for use by reference.
 *
 * @constant
 * @name Phaser.Math.Vector2.ZERO
 * @type {Vector2}
 * @since 3.1.0
 */
Vector2.ZERO = new Vector2();

module.exports = Vector2;