Sparkle

sketch.js

var unit = 50;
var count;
var mods = [];

function preload() {
    bg = loadImage("library-full.jpg");
}

function setup() {
  createCanvas(windowWidth, windowHeight);
  noStroke();
//  var wideCount = width / unit;
//  var highCount = height / unit;
//  count = wideCount * highCount;

  var index = 0;
    for (var x = 0; x < 50; x++) {
//      mods[index++] = new Module(x*unit, y*unit, unit/2, unit/2, 
//        random(0.05, 0.8), unit);
        
        mods[index++] = new Module(random(width), random(height), 
        random(0.05, 0.8), unit);
    }
}

function draw() {
  background(bg, 100);
  Sparkle();
}

function Sparkle() {
    for (var i = 0; i < count; i++) {
    mods[i].update();
    mods[i].draw();
  }
}


function Module(_x, _y, _speed, _unit) {
    this.x = _x;
    this.y = _y;
    this.speed = _speed;
    this.unit = _unit;
    this.xDir = 1;
    this.yDir = 1;
    this.alpha = random(255);
    this.lightUp = true;
}

// Custom method for updating the variables
Module.prototype.update = function() {
//  this.x = this.x + (this.speed * this.xDir);
//  if (this.x >= this.unit || this.x <= 0) {
//    this.xDir *= -1;
//    this.x = this.x + (1 * this.xDir);
//    this.y = this.y + (1 * this.yDir);
//  }
//  if (this.y >= this.unit || this.y <= 0) {
//    this.yDir *= -1;
//    this.y = this.y + (1 * this.yDir);
//  }
        
    if(this.lightUp == true) {
        this.alpha += 10;
    }
    
    if(this.alpha >= 255) {
        this.lightUp = false;
    }
    
    if(this.lightUp == false) {
        this.alpha -= 10;
    }
    
    if(this.alpha <= 0) {
//        this.x = random(width);
//        this.y = random(height);
        this.lightUp = true;
    }
    
//    this.width = this.height = map(this.alpha, 0, 255, 8, 15);
}

// Custom method for drawing the object
Module.prototype.draw = function() {
  fill(random(255), 0, 255, this.alpha);
//  ellipse(this.xOff + this.x, this.yOff + this.y, 6, 6);
//      star(this.x, this.y, map(this.alpha, 0, 255, 8, 15), 2, 4);
    ellipse(this.x, this.y, 10,10);
}

// Star shape
function star(x, y, radius1, radius2, npoints) {
  var angle = TWO_PI / npoints;
  var halfAngle = angle/2.0;
  beginShape();
  for (var a = 0; a < TWO_PI; a += angle) {
    var sx = x + cos(a) * radius2;
    var sy = y + sin(a) * radius2;
    vertex(sx, sy);
    sx = x + cos(a+halfAngle) * radius1;
    sy = y + sin(a+halfAngle) * radius1;
    vertex(sx, sy);
  }
  endShape(CLOSE);
}