function Color (opt) {
  if (opt.length == 3) {
    this.r = opt[0];
    this.g = opt[1];
    this.b = opt[2];
    this.a = 1;
  }
  else if (opt.length == 4) {
    this.r = opt[0];
    this.g = opt[1];
    this.b = opt[2];
    this.a = opt[3];
  }
}
Color.prototype.toString = function(){
  return "rgba(" + this.r + "," + this.g + "," + this.b + "," + this.a + ")";
}
Color.prototype.rgb = function(){
  return [ this.r, this.g, this.b ];
}
Color.prototype.rgba = function(){
  return [ this.r, this.g, this.b, this.a ];
}
Color.prototype.hsl = function(){
}
Color.prototype.copy = function(){
  return new Color( this.rgba() );
}
Color.prototype.alpha = function(a){
  var c = this.copy()
  c.a = a;
  return c;
}

var colors = {
  red: new Color([ 255,0,0,0.1 ]),
  blue: new Color([ 0,0,255 ]),
  black: new Color([ 0,0,0 ]),
  green: new Color([ 0,128,0 ]),
  cyan: new Color([ 0,255,255 ]),
  yellow: new Color([ 255,255,0 ]),
  peru: new Color([ 205,133,63 ]),
}