/**
* @author mrdoob / http://mrdoob.com/
* @author WestLangley / http://github.com/WestLangley
*/
export class FaceNormalsHelper {
   // THREE.FaceNormalsHelper = function(object, size, hex, linewidth) {
   //    // FaceNormalsHelper only supports THREE.Geometry
   //    this.object = object;
   //    this.size = (size !== undefined) ? size : 1;
   //    var color = (hex !== undefined) ? hex : 0xffff00;
   //    var width = (linewidth !== undefined) ? linewidth : 1;
   //    //
   //    var nNormals = 0;
   //    var objGeometry = this.object.geometry;
   //    if (objGeometry instanceof THREE.Geometry) {
   //       nNormals = objGeometry.faces.length;
   //    } else {
   //       console.warn('THREE.FaceNormalsHelper: only THREE.Geometry is supported. Use THREE.VertexNormalsHelper, instead.');
   //    }
   //    //
   //    var geometry = new THREE.BufferGeometry();
   //    var positions = new THREE.Float32Attribute(nNormals * 2 * 3, 3);
   //    geometry.addAttribute('position', positions);
   //    THREE.LineSegments.call(this, geometry, new THREE.LineBasicMaterial({ color: color, linewidth: width }));
   //    //
   //    this.matrixAutoUpdate = false;
   //    this.update();
   // };
   // THREE.FaceNormalsHelper.prototype = Object.create(THREE.LineSegments.prototype);
   // THREE.FaceNormalsHelper.prototype.constructor = THREE.FaceNormalsHelper;
   // THREE.FaceNormalsHelper.prototype.update = (function() {
   //    var v1 = new THREE.Vector3();
   //    var v2 = new THREE.Vector3();
   //    var normalMatrix = new THREE.Matrix3();
   //    return function update() {
   //       this.object.updateMatrixWorld(true);
   //       normalMatrix.getNormalMatrix(this.object.matrixWorld);
   //       var matrixWorld = this.object.matrixWorld;
   //       var position = this.geometry.attributes.position;
   //       //
   //       var objGeometry = this.object.geometry;
   //       var vertices = objGeometry.vertices;
   //       var faces = objGeometry.faces;
   //       var idx = 0;
   //       for (var i = 0, l = faces.length; i < l; i++) {
   //          var face = faces[i];
   //          var normal = face.normal;
   //          v1.copy(vertices[face.a])
   //             .add(vertices[face.b])
   //             .add(vertices[face.c])
   //             .divideScalar(3)
   //             .applyMatrix4(matrixWorld);
   //          v2.copy(normal).applyMatrix3(normalMatrix).normalize().multiplyScalar(this.size).add(v1);
   //          position.setXYZ(idx, v1.x, v1.y, v1.z);
   //          idx = idx + 1;
   //          position.setXYZ(idx, v2.x, v2.y, v2.z);
   //          idx = idx + 1;
   //       }
   //       position.needsUpdate = true;
   //       return this;
   //    }
   // } ());
}