phaser/Phaser/utils/CircleUtils.ts

/// <reference path="../_definitions.ts" />

/**
* @author       Richard Davey <rich@photonstorm.com>
* @copyright    2013 Photon Storm Ltd.
* @license      https://github.com/photonstorm/phaser/blob/master/license.txt  MIT License
* @module       Phaser
*/
module Phaser {

    /**
    * A collection of methods useful for manipulating and comparing Circle objects.
    *
    * @class CircleUtils
    */
    export class CircleUtils {

        /**
        * Returns a new Circle object with the same values for the x, y, width, and height properties as the given Circle object.
        * @method clone
        * @param {Phaser.Circle} a The Circle object to be cloned.
        * @param {Phaser.Circle} out Optional Circle object. If given the values will be set into the object, otherwise a brand new Circle object will be created and returned.
        * @return {Phaser.Circle} The cloned Circle object.
        */
        public static clone(a: Phaser.Circle, out: Phaser.Circle = new Phaser.Circle): Phaser.Circle {
            return out.setTo(a.x, a.y, a.diameter);
        }

        /**
        * Return true if the given x/y coordinates are within the Circle object.
        * @method contains
        * @param {Phaser.Circle} a The Circle to be checked.
        * @param {Number} x The X value of the coordinate to test.
        * @param {Number} y The Y value of the coordinate to test.
        * @return {bool} True if the coordinates are within this circle, otherwise false.
        */
        public static contains(a: Phaser.Circle, x: number, y: number): bool {

            //  Check if x/y are within the bounds first
            if (x >= a.left && x <= a.right && y >= a.top && y <= a.bottom)
            {
                var dx: number = (a.x - x) * (a.x - x);
                var dy: number = (a.y - y) * (a.y - y);
                return (dx + dy) <= (a.radius * a.radius);
            }

            return false;

        }

        /**
        * Return true if the coordinates of the given Point object are within this Circle object.
        * @method containsPoint
        * @param {Phaser.Circle} a The Circle object.
        * @param {Phaser.Point} point The Point object to test.
        * @return {bool} True if the coordinates are within this circle, otherwise false.
        */
        public static containsPoint(a: Phaser.Circle, point: Phaser.Point): bool {
            return CircleUtils.contains(a, point.x, point.y);
        }

        /**
        * Return true if the given Circle is contained entirely within this Circle object.
        * @method containsCircle
        * @param {Phaser.Circle} a The Circle object to test.
        * @param {Phaser.Circle} b The Circle object to test.
        * @return {bool} True if Circle B is contained entirely inside of Circle A, otherwise false.
        */
        public static containsCircle(a: Phaser.Circle, b: Phaser.Circle): bool {
            //return ((a.radius + b.radius) * (a.radius + b.radius)) >= Collision.distanceSquared(a.x, a.y, b.x, b.y);
            return true;
        }

        /**
        * Returns the distance from the center of the Circle object to the given object 
        * (can be Circle, Point or anything with x/y properties)
        * @method distanceBetween
        * @param {Phaser.Circle} a The Circle object.
        * @param {Phaser.Circle} b The target object. Must have visible x and y properties that represent the center of the object.
        * @param {bool} [optional] round Round the distance to the nearest integer (default false)
        * @return {Number} The distance between this Point object and the destination Point object.
        */
        public static distanceBetween(a: Phaser.Circle, target: any, round: bool = false): number {

            var dx = a.x - target.x;
            var dy = a.y - target.y;

            if (round === true)
            {
                return Math.round(Math.sqrt(dx * dx + dy * dy));
            }
            else
            {
                return Math.sqrt(dx * dx + dy * dy);
            }

        }

        /**
        * Determines whether the two Circle objects match. This method compares the x, y and diameter properties.
        * @method equals
        * @param {Phaser.Circle} a The first Circle object.
        * @param {Phaser.Circle} b The second Circle object.
        * @return {bool} A value of true if the object has exactly the same values for the x, y and diameter properties as this Circle object; otherwise false.
        */
        public static equals(a: Phaser.Circle, b: Phaser.Circle): bool {
            return (a.x == b.x && a.y == b.y && a.diameter == b.diameter);
        }

        /**
        * Determines whether the two Circle objects intersect.
        * This method checks the radius distances between the two Circle objects to see if they intersect.
        * @method intersects
        * @param {Phaser.Circle} a The first Circle object.
        * @param {Phaser.Circle} b The second Circle object.
        * @return {bool} A value of true if the specified object intersects with this Circle object; otherwise false.
        */
        public static intersects(a: Phaser.Circle, b: Phaser.Circle): bool {
            return (Phaser.CircleUtils.distanceBetween(a, b) <= (a.radius + b.radius));
        }

        /**
        * Returns a Point object containing the coordinates of a point on the circumference of the Circle based on the given angle.
        * @method circumferencePoint
        * @param {Phaser.Circle} a The first Circle object.
        * @param {Number} angle The angle in radians (unless asDegrees is true) to return the point from.
        * @param {bool} asDegrees Is the given angle in radians (false) or degrees (true)?
        * @param {Phaser.Point} [optional] output An optional Point object to put the result in to. If none specified a new Point object will be created.
        * @return {Phaser.Point} The Point object holding the result.
        */
        public static circumferencePoint(a: Phaser.Circle, angle: number, asDegrees: bool = false, out: Phaser.Point = new Phaser.Point): Phaser.Point {

            if (asDegrees === true)
            {
                angle = angle * Phaser.GameMath.DEG_TO_RAD;
            }

            return out.setTo(a.x + a.radius * Math.cos(angle), a.y + a.radius * Math.sin(angle));

        }

        /**
        * Checks if the given Circle and Rectangle objects intersect.
        * @method intersectsRectangle
        * @param {Phaser.Circle} c The Circle object to test.
        * @param {Phaser.Rectangle} r The Rectangle object to test.
        * @return {bool} True if the two objects intersect, otherwise false.
        */
        public static intersectsRectangle(c: Phaser.Circle, r: Phaser.Rectangle): bool {

            var cx: number = Math.abs(c.x - r.x - r.halfWidth);
            var xDist: number = r.halfWidth + c.radius;

            if (cx > xDist)
            {
                return false;
            }

            var cy: number = Math.abs(c.y - r.y - r.halfHeight);
            var yDist: number = r.halfHeight + c.radius;

            if (cy > yDist)
            {
                return false;
            }

            if (cx <= r.halfWidth || cy <= r.halfHeight)
            {
                return true;
            }

            var xCornerDist: number = cx - r.halfWidth;
            var yCornerDist: number = cy - r.halfHeight;
            var xCornerDistSq = xCornerDist * xCornerDist;
            var yCornerDistSq = yCornerDist * yCornerDist;
            var maxCornerDistSq = c.radius * c.radius;

            return xCornerDistSq + yCornerDistSq <= maxCornerDistSq;

        }

    }

}