phaser/wip/verlet/AngleConstraint.js

var Phaser;
(function (Phaser) {
    /// <reference path="../Game.ts" />
    /// <reference path="Particle.ts" />
    /// <reference path="../geom/Vector2.ts" />
    /**
    * Phaser - AngleConstraint
    *
    * constrains 3 particles to an angle
    */
    (function (Verlet) {
        var AngleConstraint = (function () {
            /**
            * Creates a new AngleConstraint object.
            * @class AngleConstraint
            * @constructor
            * @param {Number} x The x coordinate of vector2
            * @param {Number} y The y coordinate of vector2
            * @return {AngleConstraint} This object
            **/
            function AngleConstraint(a, b, c, stiffness) {
                this.a = a;
                this.b = b;
                this.c = c;
                this.angle = this.b.pos.angle2(this.a.pos, this.c.pos);
                this.stiffness = stiffness;
            }
            AngleConstraint.prototype.relax = function (stepCoef) {
                var angle = this.b.pos.angle2(this.a.pos, this.c.pos);
                var diff = angle - this.angle;
                if(diff <= -Math.PI) {
                    diff += 2 * Math.PI;
                } else if(diff >= Math.PI) {
                    diff -= 2 * Math.PI;
                }
                diff *= stepCoef * this.stiffness;
                this.a.pos = this.a.pos.rotate(this.b.pos, diff);
                this.c.pos = this.c.pos.rotate(this.b.pos, -diff);
                this.b.pos = this.b.pos.rotate(this.a.pos, diff);
                this.b.pos = this.b.pos.rotate(this.c.pos, -diff);
            };
            AngleConstraint.prototype.render = function (ctx) {
                ctx.beginPath();
                ctx.moveTo(this.a.pos.x, this.a.pos.y);
                ctx.lineTo(this.b.pos.x, this.b.pos.y);
                ctx.lineTo(this.c.pos.x, this.c.pos.y);
                var tmp = ctx.lineWidth;
                ctx.lineWidth = 5;
                ctx.strokeStyle = "rgba(255,255,0,0.2)";
                ctx.stroke();
                ctx.lineWidth = tmp;
            };
            return AngleConstraint;
        })();
        Verlet.AngleConstraint = AngleConstraint;        
    })(Phaser.Verlet || (Phaser.Verlet = {}));
    var Verlet = Phaser.Verlet;
})(Phaser || (Phaser = {}));
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