webvr js meetup initial commit

node_modules/three/examples/js/curves/NURBSCurve.js

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+/**
+ * @author renej
+ * NURBS curve object
+ *
+ * Derives from Curve, overriding getPoint and getTangent.
+ *
+ * Implementation is based on (x, y [, z=0 [, w=1]]) control points with w=weight.
+ *
+ **/
+
+
+/**************************************************************
+ *	NURBS curve
+ **************************************************************/
+
+THREE.NURBSCurve = function ( degree, knots /* array of reals */, controlPoints /* array of Vector(2|3|4) */ ) {
+
+	this.degree = degree;
+	this.knots = knots;
+	this.controlPoints = [];
+	for ( var i = 0; i < controlPoints.length; ++ i ) {
+
+		// ensure Vector4 for control points
+		var point = controlPoints[ i ];
+		this.controlPoints[ i ] = new THREE.Vector4( point.x, point.y, point.z, point.w );
+
+	}
+
+};
+
+
+THREE.NURBSCurve.prototype = Object.create( THREE.Curve.prototype );
+THREE.NURBSCurve.prototype.constructor = THREE.NURBSCurve;
+
+
+THREE.NURBSCurve.prototype.getPoint = function ( t ) {
+
+	var u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] ); // linear mapping t->u
+
+	// following results in (wx, wy, wz, w) homogeneous point
+	var hpoint = THREE.NURBSUtils.calcBSplinePoint( this.degree, this.knots, this.controlPoints, u );
+
+	if ( hpoint.w != 1.0 ) {
+
+		// project to 3D space: (wx, wy, wz, w) -> (x, y, z, 1)
+		hpoint.divideScalar( hpoint.w );
+
+	}
+
+	return new THREE.Vector3( hpoint.x, hpoint.y, hpoint.z );
+
+};
+
+
+THREE.NURBSCurve.prototype.getTangent = function ( t ) {
+
+	var u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] );
+	var ders = THREE.NURBSUtils.calcNURBSDerivatives( this.degree, this.knots, this.controlPoints, u, 1 );
+	var tangent = ders[ 1 ].clone();
+	tangent.normalize();
+
+	return tangent;
+
+};
+