Initial commit

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

@@ -0,0 +1,75 @@
+( function () {
+
+	/**
+ * NURBS curve object
+ *
+ * Derives from THREE.Curve, overriding getPoint and getTangent.
+ *
+ * Implementation is based on (x, y [, z=0 [, w=1]]) control points with w=weight.
+ *
+ **/
+
+	class NURBSCurve extends THREE.Curve {
+
+		constructor( degree, knots
+			/* array of reals */
+			, controlPoints
+			/* array of Vector(2|3|4) */
+			, startKnot
+			/* index in knots */
+			, endKnot
+			/* index in knots */
+		) {
+
+			super();
+			this.degree = degree;
+			this.knots = knots;
+			this.controlPoints = []; // Used by periodic NURBS to remove hidden spans
+
+			this.startKnot = startKnot || 0;
+			this.endKnot = endKnot || this.knots.length - 1;
+
+			for ( let i = 0; i < controlPoints.length; ++ i ) {
+
+				// ensure THREE.Vector4 for control points
+				const point = controlPoints[ i ];
+				this.controlPoints[ i ] = new THREE.Vector4( point.x, point.y, point.z, point.w );
+
+			}
+
+		}
+
+		getPoint( t, optionalTarget = new THREE.Vector3() ) {
+
+			const point = optionalTarget;
+			const u = this.knots[ this.startKnot ] + t * ( this.knots[ this.endKnot ] - this.knots[ this.startKnot ] ); // linear mapping t->u
+			// following results in (wx, wy, wz, w) homogeneous point
+
+			const 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 point.set( hpoint.x, hpoint.y, hpoint.z );
+
+		}
+
+		getTangent( t, optionalTarget = new THREE.Vector3() ) {
+
+			const tangent = optionalTarget;
+			const u = this.knots[ 0 ] + t * ( this.knots[ this.knots.length - 1 ] - this.knots[ 0 ] );
+			const ders = THREE.NURBSUtils.calcNURBSDerivatives( this.degree, this.knots, this.controlPoints, u, 1 );
+			tangent.copy( ders[ 1 ] ).normalize();
+			return tangent;
+
+		}
+
+	}
+
+	THREE.NURBSCurve = NURBSCurve;
+
+} )();