text: /**
   * @author renej
   * NURBS surface object
   *
   * Implementation is based on (x, y [, z=0 [, w=1]]) control points with w=weight.
   *
   **/
  
  
  /**************************************************************
   *	NURBS surface
   **************************************************************/
  
  THREE.NURBSSurface = function ( degree1, degree2, knots1, knots2 /* arrays of reals */, controlPoints /* array^2 of Vector(2|3|4) */) {
  
  	this.degree1 = degree1;
  	this.degree2 = degree2;
  	this.knots1 = knots1;
  	this.knots2 = knots2;
  	this.controlPoints = [];
  
  	var len1 = knots1.length - degree1 - 1;
  	var len2 = knots2.length - degree2 - 1;
  
  	// ensure Vector4 for control points
  	for (var i = 0; i < len1; ++ i) {
  		this.controlPoints[i] = [];
  		for (var j = 0; j < len2; ++ j) {
  			var point = controlPoints[i][j];
  			this.controlPoints[i][j] = new THREE.Vector4(point.x, point.y, point.z, point.w);
  		}
  	}
  };
  
  
  THREE.NURBSSurface.prototype = {
  
  	constructor: THREE.NURBSSurface,
  
  	getPoint: function ( t1, t2 ) {
  
  		var u = this.knots1[0] + t1 * (this.knots1[this.knots1.length - 1] - this.knots1[0]); // linear mapping t1->u
  		var v = this.knots2[0] + t2 * (this.knots2[this.knots2.length - 1] - this.knots2[0]); // linear mapping t2->u
  
  		return THREE.NURBSUtils.calcSurfacePoint(this.degree1, this.degree2, this.knots1, this.knots2, this.controlPoints, u, v);
  	}
  };
  
  
  