(x) class fgOBJECT {
    // material property pointer
    int material_ptr;

    // culling data
    double ref[3];
    double radius;

    // OpenGL display list for object data
    GLint display_list_ptr;
}


(x) class fgTILE {
    // culling data
    double ref[3];
    double radius;

    list < fgOBJECT > object_list;
}


class fgMATERIAL {
    int list_size;
    int counter;

public:

    // material properties
    GLfloat ambient[4], diffuse[4], specular[4];
    GLint texture_ptr;

    // transient list of objects with this material type (used for sorting
    // by material to reduce GL state changes when rendering the scene
    fgOBJECT *material_object_list[lots];

    init_list();
    append_list();
    list_traverse_init();
    next_obj()
}


class fgMATERIAL_MGR {
    list < fgMATERIAL > material_list;
}
