/**
 * @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);
	}
};