Cubeの各面に異なるマテリアルを使うときはTHREE.jsのバージョンに注意! ref: http://qiita.com/naoyashiga/items/269a9bc3658956afc379

test.js

    var cube_geo = new THREE.CubeGeometry(
        CUBE_WIDTH,
        CUBE_HEIGHT,
        CUBE_DEPTH,
        CUBE_WIDTH_SEGMENTS,
        CUBE_HEIGHT_SEGMENTS,
        CUBE_DEPTH_SEGMENTS
    );
    //空のマテリアル
    var cube_material = new THREE.MeshFaceMaterial(materials);