source: other-projects/playing-in-the-street/summer-2013/trunk/Playing-in-the-Street-WPF/Content/Web/mrdoob-three.js-4862f5f/src/extras/geometries/TorusKnotGeometry.js@ 28897

/**
 * @author oosmoxiecode
 * based on http://code.google.com/p/away3d/source/browse/trunk/fp10/Away3D/src/away3d/primitives/TorusKnot.as?spec=svn2473&r=2473
 */

THREE.TorusKnotGeometry = function ( radius, tube, radialSegments, tubularSegments, p, q, heightScale ) {

    THREE.Geometry.call( this );

    var scope = this;

    this.radius = radius || 100;
    this.tube = tube || 40;
    this.radialSegments = radialSegments || 64;
    this.tubularSegments = tubularSegments || 8;
    this.p = p || 2;
    this.q = q || 3;
    this.heightScale = heightScale || 1;
    this.grid = new Array( this.radialSegments );

    var tang = new THREE.Vector3();
    var n = new THREE.Vector3();
    var bitan = new THREE.Vector3();

    for ( var i = 0; i < this.radialSegments; ++ i ) {

        this.grid[ i ] = new Array( this.tubularSegments );
        var u = i / this.radialSegments * 2 * this.p * Math.PI;
        var p1 = getPos( u, this.q, this.p, this.radius, this.heightScale );
        var p2 = getPos( u + 0.01, this.q, this.p, this.radius, this.heightScale );
        tang.subVectors( p2, p1 );
        n.addVectors( p2, p1 );

        bitan.crossVectors( tang, n );
        n.crossVectors( bitan, tang );
        bitan.normalize();
        n.normalize();

        for ( var j = 0; j < this.tubularSegments; ++ j ) {

            var v = j / this.tubularSegments * 2 * Math.PI;
            var cx = - this.tube * Math.cos( v ); // TODO: Hack: Negating it so it faces outside.
            var cy = this.tube * Math.sin( v );

            var pos = new THREE.Vector3();
            pos.x = p1.x + cx * n.x + cy * bitan.x;
            pos.y = p1.y + cx * n.y + cy * bitan.y;
            pos.z = p1.z + cx * n.z + cy * bitan.z;

            this.grid[ i ][ j ] = scope.vertices.push( pos ) - 1;

        }

    }

    for ( var i = 0; i < this.radialSegments; ++ i ) {

        for ( var j = 0; j < this.tubularSegments; ++ j ) {

            var ip = ( i + 1 ) % this.radialSegments;
            var jp = ( j + 1 ) % this.tubularSegments;

            var a = this.grid[ i ][ j ];
            var b = this.grid[ ip ][ j ];
            var c = this.grid[ ip ][ jp ];
            var d = this.grid[ i ][ jp ];

            var uva = new THREE.Vector2( i / this.radialSegments, j / this.tubularSegments );
            var uvb = new THREE.Vector2( ( i + 1 ) / this.radialSegments, j / this.tubularSegments );
            var uvc = new THREE.Vector2( ( i + 1 ) / this.radialSegments, ( j + 1 ) / this.tubularSegments );
            var uvd = new THREE.Vector2( i / this.radialSegments, ( j + 1 ) / this.tubularSegments );

            this.faces.push( new THREE.Face3( a, b, d ) );
            this.faceVertexUvs[ 0 ].push( [ uva, uvb, uvd ] );

            this.faces.push( new THREE.Face3( b, c, d ) );
            this.faceVertexUvs[ 0 ].push( [ uvb.clone(), uvc, uvd.clone() ] );

        }
    }

    this.computeCentroids();
    this.computeFaceNormals();
    this.computeVertexNormals();

    function getPos( u, in_q, in_p, radius, heightScale ) {

        var cu = Math.cos( u );
        var su = Math.sin( u );
        var quOverP = in_q / in_p * u;
        var cs = Math.cos( quOverP );

        var tx = radius * ( 2 + cs ) * 0.5 * cu;
        var ty = radius * ( 2 + cs ) * su * 0.5;
        var tz = heightScale * radius * Math.sin( quOverP ) * 0.5;

        return new THREE.Vector3( tx, ty, tz );

    }

};

THREE.TorusKnotGeometry.prototype = Object.create( THREE.Geometry.prototype );