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

/**
 * @author hughes
 */

THREE.CircleGeometry = function ( radius, segments, thetaStart, thetaLength ) {

    THREE.Geometry.call( this );

    this.radius = radius = radius || 50;
    this.segments = segments = segments !== undefined ? Math.max( 3, segments ) : 8;

    this.thetaStart = thetaStart = thetaStart !== undefined ? thetaStart : 0;
    this.thetaLength = thetaLength = thetaLength !== undefined ? thetaLength : Math.PI * 2;

    var i, uvs = [],
    center = new THREE.Vector3(), centerUV = new THREE.Vector2( 0.5, 0.5 );

    this.vertices.push(center);
    uvs.push( centerUV );

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

        var vertex = new THREE.Vector3();
        var segment = thetaStart + i / segments * thetaLength;

        vertex.x = radius * Math.cos( segment );
        vertex.y = radius * Math.sin( segment );

        this.vertices.push( vertex );
        uvs.push( new THREE.Vector2( ( vertex.x / radius + 1 ) / 2, ( vertex.y / radius + 1 ) / 2 ) );

    }

    var n = new THREE.Vector3( 0, 0, 1 );

    for ( i = 1; i <= segments; i ++ ) {

        var v1 = i;
        var v2 = i + 1 ;
        var v3 = 0;

        this.faces.push( new THREE.Face3( v1, v2, v3, [ n.clone(), n.clone(), n.clone() ] ) );
        this.faceVertexUvs[ 0 ].push( [ uvs[ i ].clone(), uvs[ i + 1 ].clone(), centerUV.clone() ] );

    }

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

    this.boundingSphere = new THREE.Sphere( new THREE.Vector3(), radius );

};

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