Initial commit

HTML/ThreeJS/node_modules/three/examples/js/geometries/ParametricGeometry.js

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+( function () {
+
+	/**
+ * Parametric Surfaces Geometry
+ * based on the brilliant article by @prideout https://prideout.net/blog/old/blog/index.html@p=44.html
+ */
+
+	class ParametricGeometry extends THREE.BufferGeometry {
+
+		constructor( func = ( u, v, target ) => target.set( u, v, Math.cos( u ) * Math.sin( v ) ), slices = 8, stacks = 8 ) {
+
+			super();
+			this.type = 'ParametricGeometry';
+			this.parameters = {
+				func: func,
+				slices: slices,
+				stacks: stacks
+			}; // buffers
+
+			const indices = [];
+			const vertices = [];
+			const normals = [];
+			const uvs = [];
+			const EPS = 0.00001;
+			const normal = new THREE.Vector3();
+			const p0 = new THREE.Vector3(),
+				p1 = new THREE.Vector3();
+			const pu = new THREE.Vector3(),
+				pv = new THREE.Vector3();
+
+			if ( func.length < 3 ) {
+
+				console.error( 'THREE.ParametricGeometry: Function must now modify a THREE.Vector3 as third parameter.' );
+
+			} // generate vertices, normals and uvs
+
+
+			const sliceCount = slices + 1;
+
+			for ( let i = 0; i <= stacks; i ++ ) {
+
+				const v = i / stacks;
+
+				for ( let j = 0; j <= slices; j ++ ) {
+
+					const u = j / slices; // vertex
+
+					func( u, v, p0 );
+					vertices.push( p0.x, p0.y, p0.z ); // normal
+					// approximate tangent vectors via finite differences
+
+					if ( u - EPS >= 0 ) {
+
+						func( u - EPS, v, p1 );
+						pu.subVectors( p0, p1 );
+
+					} else {
+
+						func( u + EPS, v, p1 );
+						pu.subVectors( p1, p0 );
+
+					}
+
+					if ( v - EPS >= 0 ) {
+
+						func( u, v - EPS, p1 );
+						pv.subVectors( p0, p1 );
+
+					} else {
+
+						func( u, v + EPS, p1 );
+						pv.subVectors( p1, p0 );
+
+					} // cross product of tangent vectors returns surface normal
+
+
+					normal.crossVectors( pu, pv ).normalize();
+					normals.push( normal.x, normal.y, normal.z ); // uv
+
+					uvs.push( u, v );
+
+				}
+
+			} // generate indices
+
+
+			for ( let i = 0; i < stacks; i ++ ) {
+
+				for ( let j = 0; j < slices; j ++ ) {
+
+					const a = i * sliceCount + j;
+					const b = i * sliceCount + j + 1;
+					const c = ( i + 1 ) * sliceCount + j + 1;
+					const d = ( i + 1 ) * sliceCount + j; // faces one and two
+
+					indices.push( a, b, d );
+					indices.push( b, c, d );
+
+				}
+
+			} // build geometry
+
+
+			this.setIndex( indices );
+			this.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
+			this.setAttribute( 'normal', new THREE.Float32BufferAttribute( normals, 3 ) );
+			this.setAttribute( 'uv', new THREE.Float32BufferAttribute( uvs, 2 ) );
+
+		}
+
+	}
+
+	THREE.ParametricGeometry = ParametricGeometry;
+
+} )();