code: function strokeEllipse(x, y, w, h, fill) {
           if (fill === true) {
             this.fillEllipse(x, y, w, h);
           } else {
             // XXX to be optimzed using a specific shader
             var len = Math.floor(24 * Math.sqrt(w)) || Math.floor(12 * Math.sqrt(w + h));
             var segment = me.Math.TAU / len;
             var points = this._glPoints,
                 i; // Grow internal points buffer if necessary
  
             for (i = points.length; i < len; i++) {
               points.push(new me.Vector2d());
             } // calculate and draw all segments
  
  
             for (i = 0; i < len; i++) {
               points[i].x = x + Math.sin(segment * -i) * w;
               points[i].y = y + Math.cos(segment * -i) * h;
             } // batch draw all lines
  
  
             this.compositor.drawLine(points, len);
           }
         }
docs: Stroke an ellipse at the specified coordinates with given radius
  @name strokeEllipse
  @memberOf me.WebGLRenderer.prototype
  @function
  @param {Number} x ellipse center point x-axis
  @param {Number} y ellipse center point y-axis
  @param {Number} w horizontal radius of the ellipse
  @param {Number} h vertical radius of the ellipse