Put ray lookAt function

src/math/Ray.js

@@ -45,6 +45,12 @@ THREE.Ray.prototype = {
 
 	},
 
+	lookAt: function ( v ) {
+
+		this.direction.copy( v ).sub( this.origin ).normalize();
+
+	},
+
 	recast: function () {
 
 		var v1 = new THREE.Vector3();
@@ -239,11 +245,8 @@ THREE.Ray.prototype = {
 		return function ( sphere, optionalTarget ) {
 
 			v1.subVectors( sphere.center, this.origin );
-
 			var tca = v1.dot( this.direction );
-
 			var d2 = v1.dot( v1 ) - tca * tca;
-
 			var radius2 = sphere.radius * sphere.radius;
 
 			if ( d2 > radius2 ) return null;