GL::Sequence::Step *step = &shadow_seq->add_step("shadow", content);
step->set_depth_test(&GL::DepthTest::lequal());
shadow_map = make_unique<GL::ShadowMap>(shadow_size, *sky, sun, *shadow_seq);
GL::Sequence::Step *step = &shadow_seq->add_step("shadow", content);
step->set_depth_test(&GL::DepthTest::lequal());
shadow_map = make_unique<GL::ShadowMap>(shadow_size, *sky, sun, *shadow_seq);