adding THREE.ArrowHelper

src/extras/helpers/ArrowHelper.js

+/**
+ * @author WestLangley / https://github.com/WestLangley
+ * @author zz85 / https://github.com/zz85
+ */
+THREE.ArrowHelper = function (origin, dir, scale, color) {
+
+    THREE.Object3D.call( this );
+
+    // line
+    var lineGeometry = new THREE.Geometry();
+    lineGeometry.vertices.push( new THREE.Vertex() );
+    lineGeometry.vertices.push( new THREE.Vertex( new THREE.Vector3( 0, 1, 0 ) ) );
+    line = new THREE.Line( lineGeometry, new THREE.LineBasicMaterial( { color : color } ) );
+    this.add( line );
+    
+    // tip
+    var coneGeometry = new THREE.CylinderGeometry( 0, 0.05, 0.25, 5, 1 );
+    cone = new THREE.Mesh( coneGeometry, new THREE.MeshBasicMaterial( { color : color } ) );
+    cone.position.set( 0, 1, 0 );
+    this.add( cone );
+    
+    // position
+    this.position = origin;
+    
+    this.orientate(dir);
+    
+    this.scale.set( scale, scale, scale );
+
+};
+
+THREE.ArrowHelper.prototype = new THREE.Object3D();
+THREE.ArrowHelper.prototype.constructor = THREE.ArrowHelper;
+
+THREE.ArrowHelper.prototype.orientate = function(dir) {
+      // orientation - object matrix
+    var axis = new THREE.Vector3( 0, 1, 0 ).crossSelf( dir );
+    var radians = Math.acos( new THREE.Vector3( 0, 1, 0 ).dot( dir.normalize() ) );
+    var rotationMatrix = new THREE.Matrix4();
+    rotationMatrix.setRotationAxis( axis.normalize(), radians );
+    this.matrix.multiplySelf( rotationMatrix );
+    
+    // orientation - euler rotation vector
+    this.rotation.getRotationFromMatrix( this.matrix, this.scale );
+};
\ No newline at end of file

utils/build.py

@@ -121,6 +121,7 @@ EXTRAS_FILES = [
 'extras/geometries/OctahedronGeometry.js',
 'extras/geometries/TetrahedronGeometry.js',
 'extras/helpers/AxisHelper.js',
+'extras/helpers/ArrowHelper.js',
 'extras/helpers/CameraHelper.js',
 'extras/modifiers/SubdivisionModifier.js',
 'extras/loaders/Loader.js',