phaser/src/geom/circle/Circle.js

var Class = require('../../utils/Class');
var Contains = require('./Contains');
var GetPoint = require('./GetPoint');
var GetPoints = require('./GetPoints');
var Random = require('./Random');

/**
 * A Circle object.
 *
 * This is a geometry object, containing numerical values and related methods to inspect and modify them.
 * It is not a Game Object, in that you cannot add it to the display list, and it has no texture.
 * To render a Circle you should look at the capabilities of the Graphics class.
 *
 * @class Circle
 * @memberOf Phaser.Geom
 * @constructor
 * @since 3.0.0
 *
 * @param {number} [x=0] - The x position of the center of the circle.
 * @param {number} [y=0] - The y position of the center of the circle.
 * @param {number} [radius=0] - The radius of the circle.
 */
var Circle = new Class({

    initialize:

    function Circle (x, y, radius)
    {
        if (x === undefined) { x = 0; }
        if (y === undefined) { y = 0; }
        if (radius === undefined) { radius = 0; }

        /**
         * The x position of the center of the circle.
         *
         * @property {number} x
         * @since 3.0.0
         */
        this.x = x;

        /**
         * The y position of the center of the circle.
         *
         * @property {number} y
         * @since 3.0.0
         */
        this.y = y;

        /**
         * The internal radius of the circle.
         *
         * @property {number} _radius
         * @private
         * @since 3.0.0
         */
        this._radius = radius;

        /**
         * The internal diameter of the circle.
         *
         * @property {number} _diameter
         * @private
         * @since 3.0.0
         */
        this._diameter = radius * 2;
    },

    /**
     * Check to see if the Circle contains the given x / y coordinates.
     *
     * @method Phaser.Geom.Circle#contains
     * @since 3.0.0
     *
     * @param {number} x - The x coordinate to check within the circle.
     * @param {number} y - The y coordinate to check within the circle.
     *
     * @return {boolean} True if the coordinates are within the circle, otherwise false.
     */
    contains: function (x, y)
    {
        return Contains(this, x, y);
    },

    /**
     * Returns a Point object containing the coordinates of a point on the circumference of the Circle
     * based on the given angle normalized to the range 0 to 1. I.e. a value of 0.5 will give the point
     * at 180 degrees around the circle.
     *
     * @method Phaser.Geom.Circle#getPoint
     * @since 3.0.0
     *
     * @param {float} position - A value between 0 and 1, where 0 equals 0 degrees, 0.5 equals 180 degrees and 1 equals 360 around the circle.
     * @param {Phaser.Geom.Point|object} [out] - An object to store the return values in. If not given a Point object will be created.
     *
     * @return {Phaser.Geom.Point|object} A Point, or point-like object, containing the coordinates of the point around the circle.
     */
    getPoint: function (position, point)
    {
        return GetPoint(this, position, point);
    },

    /**
     * Returns an array of Point objects containing the coordinates of the points around the circumference of the Circle,
     * based on the given quantity or stepRate values.
     *
     * @method Phaser.Geom.Circle#getPoints
     * @since 3.0.0
     *
     * @param {integer} quantity - The amount of points to return. If a falsey value the quantity will be derived from the `stepRate` instead.
     * @param {number} [stepRate] - Sets the quantity by getting the circumference of the circle and dividing it by the stepRate.
     * @param {array} [output] - An array to insert the points in to. If not provided a new array will be created.
     *
     * @return {Phaser.Geom.Point[]} An array of Point objects pertaining to the points around the circumference of the circle.
     */
    getPoints: function (quantity, stepRate, output)
    {
        return GetPoints(this, quantity, stepRate, output);
    },

    /**
     * Returns a uniformly distributed random point from anywhere within the Circle.
     *
     * @method Phaser.Geom.Circle#getRandomPoint
     * @since 3.0.0
     *
     * @param {Phaser.Geom.Point|object} [point] - A Point or point-like object to set the random `x` and `y` values in.
     *
     * @return {Phaser.Geom.Point|object} A Point object with the random values set in the `x` and `y` properties.
     */
    getRandomPoint: function (point)
    {
        return Random(this, point);
    },

    /**
     * Sets the x, y and radius of this circle.
     *
     * @method Phaser.Geom.Circle#setTo
     * @since 3.0.0
     *
     * @param {number} [x=0] - The x position of the center of the circle.
     * @param {number} [y=0] - The y position of the center of the circle.
     * @param {number} [radius=0] - The radius of the circle.
     *
     * @return {Phaser.Geom.Circle} This Circle object.
     */
    setTo: function (x, y, radius)
    {
        this.x = x;
        this.y = y;
        this._radius = radius;
        this._diameter = radius * 2;

        return this;
    },

    /**
     * Sets this Circle to be empty with a radius of zero.
     * Does not change its position.
     *
     * @method Phaser.Geom.Circle#setEmpty
     * @since 3.0.0
     *
     * @return {Phaser.Geom.Circle} This Circle object.
     */
    setEmpty: function ()
    {
        this._radius = 0;
        this._diameter = 0;

        return this;
    },

    /**
     * Sets the position of this Circle.
     *
     * @method Phaser.Geom.Circle#setPosition
     * @since 3.0.0
     *
     * @param {number} [x=0] - The x position of the center of the circle.
     * @param {number} [y=0] - The y position of the center of the circle.
     *
     * @return {Phaser.Geom.Circle} This Circle object.
     */
    setPosition: function (x, y)
    {
        if (y === undefined) { y = x; }

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

        return this;
    },

    /**
     * Checks to see if the Circle is empty: has a radius of zero.
     *
     * @method Phaser.Geom.Circle#isEmpty
     * @since 3.0.0
     *
     * @return {boolean} True if the Circle is empty, otherwise false.
     */
    isEmpty: function ()
    {
        return (this._radius <= 0);
    },

    /**
     * The radius of the Circle.
     * 
     * @name Phaser.Geom.Circle#radius
     * @property {number} radius
     * @since 3.0.0
     */
    radius: {

        get: function ()
        {
            return this._radius;
        },

        set: function (value)
        {
            this._radius = value;
            this._diameter = value * 2;
        }

    },

    /**
     * The diameter of the Circle.
     * 
     * @name Phaser.Geom.Circle#diameter
     * @property {number} diameter
     * @since 3.0.0
     */
    diameter: {

        get: function ()
        {
            return this._diameter;
        },

        set: function (value)
        {
            this._diameter = value;
            this._radius = value * 0.5;
        }

    },

    /**
     * The left position of the Circle.
     * 
     * @name Phaser.Geom.Circle#left
     * @property {number} left
     * @since 3.0.0
     */
    left: {

        get: function ()
        {
            return this.x - this._radius;
        },

        set: function (value)
        {
            this.x = value + this._radius;
        }

    },

    /**
     * The right position of the Circle.
     * 
     * @name Phaser.Geom.Circle#right
     * @property {number} right
     * @since 3.0.0
     */
    right: {

        get: function ()
        {
            return this.x + this._radius;
        },

        set: function (value)
        {
            this.x = value - this._radius;
        }

    },

    /**
     * The top position of the Circle.
     * 
     * @name Phaser.Geom.Circle#top
     * @property {number} top
     * @since 3.0.0
     */
    top: {

        get: function ()
        {
            return this.y - this._radius;
        },

        set: function (value)
        {
            this.y = value + this._radius;
        }

    },

    /**
     * The bottom position of the Circle.
     * 
     * @name Phaser.Geom.Circle#bottom
     * @property {number} bottom
     * @since 3.0.0
     */
    bottom: {

        get: function ()
        {
            return this.y + this._radius;
        },

        set: function (value)
        {
            this.y = value - this._radius;
        }

    }

});

module.exports = Circle;