three.js/src/extras/geometries/TorusGeometry.js

/**
 * @author oosmoxiecode
 * @author mrdoob / http://mrdoob.com/
 * based on http://code.google.com/p/away3d/source/browse/trunk/fp10/Away3DLite/src/away3dlite/primitives/Torus.as?r=2888
 */

THREE.TorusGeometry = function ( radius, tube, radialSegments, tubularSegments, arc ) {

	THREE.Geometry.call( this );

	this.type = 'TorusGeometry';

	this.parameters = {
		radius: radius,
		tube: tube,
		radialSegments: radialSegments,
		tubularSegments: tubularSegments,
		arc: arc
	};

	radius = radius || 100;
	tube = tube || 40;
	radialSegments = radialSegments || 8;
	tubularSegments = tubularSegments || 6;
	arc = arc || Math.PI * 2;

	var center = new THREE.Vector3(), uvs = [], normals = [];

	for ( var j = 0; j <= radialSegments; j ++ ) {

		for ( var i = 0; i <= tubularSegments; i ++ ) {

			var u = i / tubularSegments * arc;
			var v = j / radialSegments * Math.PI * 2;

			center.x = radius * Math.cos( u );
			center.y = radius * Math.sin( u );

			var vertex = new THREE.Vector3();
			vertex.x = ( radius + tube * Math.cos( v ) ) * Math.cos( u );
			vertex.y = ( radius + tube * Math.cos( v ) ) * Math.sin( u );
			vertex.z = tube * Math.sin( v );

			this.vertices.push( vertex );

			uvs.push( new THREE.Vector2( i / tubularSegments, j / radialSegments ) );
			normals.push( vertex.clone().sub( center ).normalize() );

		}

	}

	for ( var j = 1; j <= radialSegments; j ++ ) {

		for ( var i = 1; i <= tubularSegments; i ++ ) {

			var a = ( tubularSegments + 1 ) * j + i - 1;
			var b = ( tubularSegments + 1 ) * ( j - 1 ) + i - 1;
			var c = ( tubularSegments + 1 ) * ( j - 1 ) + i;
			var d = ( tubularSegments + 1 ) * j + i;

			var face = new THREE.Face3( a, b, d, [ normals[ a ].clone(), normals[ b ].clone(), normals[ d ].clone() ] );
			this.faces.push( face );
			this.faceVertexUvs[ 0 ].push( [ uvs[ a ].clone(), uvs[ b ].clone(), uvs[ d ].clone() ] );

			face = new THREE.Face3( b, c, d, [ normals[ b ].clone(), normals[ c ].clone(), normals[ d ].clone() ] );
			this.faces.push( face );
			this.faceVertexUvs[ 0 ].push( [ uvs[ b ].clone(), uvs[ c ].clone(), uvs[ d ].clone() ] );

		}

	}

	this.computeFaceNormals();

};

THREE.TorusGeometry.prototype = Object.create( THREE.Geometry.prototype );
THREE.TorusGeometry.prototype.constructor = THREE.TorusGeometry;

THREE.TorusGeometry.prototype.clone = function () {

	var geometry = new THREE.TorusGeometry(
		this.parameters.radius,
		this.parameters.tube,
		this.parameters.radialSegments,
		this.parameters.tubularSegments,
		this.parameters.arc
	);

	return geometry;

};