three.proton/src/emitter/FollowEmitter.js

three.Proton is an easily customizable html5 particle engine for three.js

(function(Proton, undefined) {
    /**
     * The FollowEmitter class inherits from Proton.Emitter
     *
     * use the FollowEmitter will emit particle when mousemoving
     *
     * @class Proton.FollowEmitter
     * @constructor
     * @param {Element} mouseTarget mouseevent's target;
     * @param {Number} ease the easing of following speed;
     * @default 0.7
     * @param {Object} pObj the parameters object;
     */
    function FollowEmitter(mouseTarget, ease, pObj) {
        this.mouseTarget = Proton.Util.initValue(mouseTarget, window);
        this.ease = Proton.Util.initValue(ease, .7);
        this._allowEmitting = false;
        this.initEventHandler();
        FollowEmitter._super_.call(this, pObj);
    };

    Proton.Util.inherits(FollowEmitter, Proton.Emitter);
    FollowEmitter.prototype.initEventHandler = function() {
        var self = this;
        this.mousemoveHandler = function(e) {
            self.mousemove.call(self, e);
        };

        this.mousedownHandler = function(e) {
            self.mousedown.call(self, e);
        };

        this.mouseupHandler = function(e) {
            self.mouseup.call(self, e);
        };
        
        this.mouseTarget.addEventListener('mousemove', this.mousemoveHandler, false);
    }

    /**
     * start emit particle
     * @method emit
     */
    FollowEmitter.prototype.emit = function() {
        this._allowEmitting = true;
    }

    /**
     * stop emiting
     * @method stopEmit
     */
    FollowEmitter.prototype.stopEmit = function() {
        this._allowEmitting = false;
    }

    FollowEmitter.prototype.setCameraAndCanvas = function(camera, canvas) {
        this.camera = camera;
        this.canvas = canvas;
    }

    FollowEmitter.prototype.mousemove = function(e) {
        if (e.layerX || e.layerX == 0) {
            this.p.x += (e.layerX - this.p.x) * this.ease;
            this.p.y += (e.layerY - this.p.y) * this.ease;
        } else if (e.offsetX || e.offsetX == 0) {
            this.p.x += (e.offsetX - this.p.x) * this.ease;
            this.p.y += (e.offsetY - this.p.y) * this.ease;
        }

        this.p.copy(Proton.THREEUtil.toSpacePos(this.p, this.camera, this.canvas));

        if (this._allowEmitting)
            FollowEmitter._super_.prototype.emit.call(this, 'once');
    };

    /**
     * Destory this Emitter
     * @method destroy
     */
    FollowEmitter.prototype.destroy = function() {
        FollowEmitter._super_.prototype.destroy.call(this);
        this.mouseTarget.removeEventListener('mousemove', this.mousemoveHandler, false);
    }

    Proton.FollowEmitter = FollowEmitter;
})(Proton);