code: function strokeLine(startX, startY, endX, endY) {
           var points = this._glPoints;
           points[0].x = startX;
           points[0].y = startY;
           points[1].x = endX;
           points[1].y = endY;
           this.compositor.drawLine(points, 2, true);
         }
docs: Stroke a line of the given two points
  @name strokeLine
  @memberOf me.WebGLRenderer.prototype
  @function
  @param {Number} startX the start x coordinate
  @param {Number} startY the start y coordinate
  @param {Number} endX the end x coordinate
  @param {Number} endY the end y coordinate