case 'patch': {
         var cplines = this.xmlelem.children;
         var cPointsArray  = [];
          var i = 0;
          var j = 0;

          for(; i < cplines.length; i++) {

            for(; j < cplines[i].children.length; j++) {
              var x = this.graph.reader.getFloat(cplines[i].children[j], 'xx');
              var y = this.graph.reader.getFloat(cplines[i].children[j], 'yy');
              var z = this.graph.reader.getFloat(cplines[i].children[j], 'zz');
              var w = this.graph.reader.getFloat(cplines[i].children[j], 'ww');
              cPointsArray.push(vec4.fromValues(x, y, z, w));
         }
        }

          var degreeU = i-1;
          var degreeV = j-1;

          var leaf = new MyNurb(this.graph.scene, this.args[0], this.args[1], degreeU, degreeV, cPointsArray);
          break;
      }
        default:
            return;
    }