Cursor trails

	var al = [];

    function setup() {
        createCanvas(windowWidth, windowHeight);
    }
    function draw() {
        background('#fff');

        //닷 
        stroke('rgb(237, 34, 93)');
        strokeWeight(2);
        for(var i=0; i<width; i=i+20) {
            for(var j=0; j<height; j=j+20) {
                point(i, j);
            }                         
        }
        strokeWeight(1);

        al.push(new Rays());
        for( var i = 0; i < al.length; i++ ) {
            var r = al[i];
            r.applyForce(new p5.Vector(random(0.5, 0.5), random(0.5, 0.5)));
            r.update();
            r.render();
            if(r.isDead())
            al.shift();
        }
    }
    function windowResized() {
        resizeCanvas(windowWidth, windowHeight);
    }
    function Rays() {
        this.counter = 0;
        this.position = new p5.Vector(mouseX,mouseY );
        this.velocity = new p5.Vector(0, 0);
        this.acceleration = new p5.Vector(0, 0);
        this.lifeSpan = 3;
    }
    Rays.prototype.applyForce = function(force) {
        acceleration = force;
    }
    Rays.prototype.update = function() {
        this.velocity.add(this.acceleration);
        this.position.add(this.velocity);
        this.lifeSpan -= 0.04;
    }
    Rays.prototype.render = function() {
        var c = color('rgba(237, 34, 93,' + this.lifeSpan + ')');
        stroke( c ); 
        line(this.position.x, this.position.y, pmouseX, pmouseY);
    }
    Rays.prototype.isDead = function() {
        if( this.lifeSpan < 0.001 )
            return true;
        else
            return false;
    }