code: function (x, y, radius, start, end, antiClockwise, fill) {
              if (fill === true ) {
                  this.fillArc(x, y, radius, start, end, antiClockwise);
              } else {
                  // XXX to be optimzed using a specific shader
                  var points = this._glPoints;
                  var len = Math.floor(24 * Math.sqrt(radius * 2));
                  var theta = (end - start) / (len * 2);
                  var theta2 = theta * 2;
                  var cos_theta = Math.cos(theta);
                  var sin_theta = Math.sin(theta);
  
                  // Grow internal points buffer if necessary
                  for (i = points.length; i < len + 1; i++) {
                      points.push(new me.Vector2d());
                  }
  
                  // calculate and draw all segments
                  for (var i = 0; i < len; i++) {
                      var angle = ((theta) + start + (theta2 * i));
                      var cos = Math.cos(angle);
                      var sin = -Math.sin(angle);
  
                      points[i].x = x + (((cos_theta * cos) + (sin_theta * sin)) * radius);
                      points[i].y = y + (((cos_theta * -sin) + (sin_theta * cos)) * radius);
                  }
                  // batch draw all lines
                  this.compositor.drawLine(points, len, true);
              }
          }
docs: Stroke an arc at the specified coordinates with given radius, start and end points
  @name strokeArc
  @memberOf me.WebGLRenderer.prototype
  @function
  @param {Number} x arc center point x-axis
  @param {Number} y arc center point y-axis
  @param {Number} radius
  @param {Number} start start angle in radians
  @param {Number} end end angle in radians
  @param {Boolean} [antiClockwise=false] draw arc anti-clockwise