code: function (col, opaque) {
              this.save();
              this.resetTransform();
              this.currentColor.copy(col);
              if (opaque) {
                  this.compositor.clear();
              }
              else {
                  this.fillRect(0, 0, this.canvas.width, this.canvas.height);
              }
              this.restore();
          }
docs: Clears the gl context with the given color.
  @name clearColor
  @memberOf me.WebGLRenderer.prototype
  @function
  @param {me.Color|String} color CSS color.
  @param {Boolean} [opaque=false] Allow transparency [default] or clear the surface completely [true]