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

/**
 * @author zz85 / https://github.com/zz85
 * Parametric Surfaces Geometry
 * based on the brilliant article by @prideout http://prideout.net/blog/?p=44
 *
 * new THREE.ParametricGeometry( parametricFunction, uSegments, ySegements );
 *
 */

THREE.ParametricGeometry = function ( func, slices, stacks ) {

    THREE.Geometry.call( this );

    var verts = this.vertices;
    var faces = this.faces;
    var uvs = this.faceVertexUvs[ 0 ];

    var i, il, j, p;
    var u, v;

    var stackCount = stacks + 1;
    var sliceCount = slices + 1;

    for ( i = 0; i <= stacks; i ++ ) {

        v = i / stacks;

        for ( j = 0; j <= slices; j ++ ) {

            u = j / slices;

            p = func( u, v );
            verts.push( p );

        }
    }

    var a, b, c, d;
    var uva, uvb, uvc, uvd;

    for ( i = 0; i < stacks; i ++ ) {

        for ( j = 0; j < slices; j ++ ) {

            a = i * sliceCount + j;
            b = i * sliceCount + j + 1;
            c = (i + 1) * sliceCount + j + 1;
            d = (i + 1) * sliceCount + j;

            uva = new THREE.Vector2( j / slices, i / stacks );
            uvb = new THREE.Vector2( ( j + 1 ) / slices, i / stacks );
            uvc = new THREE.Vector2( ( j + 1 ) / slices, ( i + 1 ) / stacks );
            uvd = new THREE.Vector2( j / slices, ( i + 1 ) / stacks );

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

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

        }

    }

    // console.log(this);

    // magic bullet
    // var diff = this.mergeVertices();
    // console.log('removed ', diff, ' vertices by merging');

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

};

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