Upload cube map.
virtual void CL_TextureProvider::set_cube_map( CL_PixelBuffer & cube_map_positive_x, CL_PixelBuffer & cube_map_negative_x, CL_PixelBuffer & cube_map_positive_y, CL_PixelBuffer & cube_map_negative_y, CL_PixelBuffer & cube_map_positive_z, CL_PixelBuffer & cube_map_negative_z, int level);