void loadMaterials() throws Exception {
material = new N3Material(scene, "mat1");
InputStream is = new FileInputStream("files/nu3a.png");
N3JDKImageLoader loader = new N3JDKImageLoader(is);
N3Texture2D texture = new N3Texture2D(scene, "textura1");
texture.genTexture(loader, render);
material.addTexture(texture);
material.setAmbientColor(new N3ColorRGBA(1, 1, 1));
material.setDiffuseColor(new N3ColorRGBA(1, 1, 1));