distant_shprog(Resources::get_global().get<Program>("_sky_distant.glsl.shader")),
fullscreen_mesh(Resources::get_global().get<Mesh>("_fullscreen_quad.mesh")),
backdrop_shprog(Resources::get_global().get<Program>("_sky_backdrop.glsl.shader")),
distant_shprog(Resources::get_global().get<Program>("_sky_distant.glsl.shader")),
fullscreen_mesh(Resources::get_global().get<Mesh>("_fullscreen_quad.mesh")),
backdrop_shprog(Resources::get_global().get<Program>("_sky_backdrop.glsl.shader")),