如何应用threejs实现立方体每个面用图片替换

var geometry = new THREE.BoxGeometry(200, 200, 200);
var materialsbg = [];

for (var i = 0; i < geometry.faces.length / 2; i += 1) {
    var material = new THREE.MeshBasicMaterial({
        map: THREE.ImageUtils.loadTexture('./css/images/' + (i + 1) + '.png',
        )
    });
    materialsbg[i] = material

}

cube = new THREE.Mesh(geometry, materialsbg);
scene.add(cube);