code: function RainyDay(options) {
      this.img = document.getElementById(options.element);
      this.opacity = options.opacity || 1;
      this.blurRadius = options.blur || 10;
      this.w = this.img.clientWidth;
      this.h = this.img.clientHeight;
      this.drops = [];
  
      // prepare canvas elements
      this.canvas = this.prepareCanvas(this.img);
      this.prepareBackground(this.w, this.h);
      this.prepareGlass();
  
      // assume defaults
      this.reflection = this.REFLECTION_MINIATURE;
      this.trail = this.TRAIL_DROPS;
      this.gravity = this.GRAVITY_NON_LINEAR;
      this.collision = this.COLLISION_SIMPLE;
      this.VARIABLE_GRAVITY_THRESHOLD = 3;
      this.VARIABLE_GRAVITY_ANGLE = Math.PI / 2;
      this.VARIABLE_GRAVITY_ANGLE_VARIANCE = 0;
      this.VARIABLE_FPS = options.fps;
      this.VARIABLE_FILL_STYLE = '#8ED6FF';
      this.VARIABLE_COLLISIONS = true;
      this.REFLECTION_SCALEDOWN_FACTOR = 5;
      this.REFLECTION_DROP_MAPPING_WIDTH = 200;
      this.REFLECTION_DROP_MAPPING_HEIGHT = 200;
  }
docs: Defines a new instance of the rainyday.js.
  @param options options element with script parameters