解答：取代 createTail() 裡創造尾巴的部分：

var tailTexture = THREE.ImageUtils.loadTexture( '/cs291/texture/feather.png' );
var tail = new THREE.Mesh(
	new THREE.PlaneGeometry( 100, 100, 1, 1 ),
	new THREE.MeshLambertMaterial(
		{ map: tailTexture, side: THREE.DoubleSide, transparent: true } ) );