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

/**
 * @author mrdoob / http://mrdoob.com/
 * @author WestLangley / http://github.com/WestLangley
*/

THREE.FaceNormalsHelper = function ( object, size, hex, linewidth ) {

    this.object = object;

    this.size = ( size !== undefined ) ? size : 1;

    var color = ( hex !== undefined ) ? hex : 0xffff00;

    var width = ( linewidth !== undefined ) ? linewidth : 1;

    var geometry = new THREE.Geometry();

    var faces = this.object.geometry.faces;

    for ( var i = 0, l = faces.length; i < l; i ++ ) {

        geometry.vertices.push( new THREE.Vector3() );
        geometry.vertices.push( new THREE.Vector3() );

    }

    THREE.Line.call( this, geometry, new THREE.LineBasicMaterial( { color: color, linewidth: width } ), THREE.LinePieces );

    this.matrixAutoUpdate = false;

    this.normalMatrix = new THREE.Matrix3();

    this.update();

};

THREE.FaceNormalsHelper.prototype = Object.create( THREE.Line.prototype );

THREE.FaceNormalsHelper.prototype.update = ( function ( object ) {

    var v1 = new THREE.Vector3();

    return function ( object ) {

        this.object.updateMatrixWorld( true );

        this.normalMatrix.getNormalMatrix( this.object.matrixWorld );

        var vertices = this.geometry.vertices;

        var faces = this.object.geometry.faces;

        var worldMatrix = this.object.matrixWorld;

        for ( var i = 0, l = faces.length; i < l; i ++ ) {

            var face = faces[ i ];

            v1.copy( face.normal ).applyMatrix3( this.normalMatrix ).normalize().multiplyScalar( this.size );

            var idx = 2 * i;

            vertices[ idx ].copy( face.centroid ).applyMatrix4( worldMatrix );

            vertices[ idx + 1 ].addVectors( vertices[ idx ], v1 );

        }

        this.geometry.verticesNeedUpdate = true;

        return this;

    }

}());