Object Layer Control

This picture shows explicit layering control for objects, a proposed extension for X-Plane 850. In this case the blue square, red square, and yellow cube are three separate objects, all sharing a texture. The blue and red objects use polygon-offset (ATTR_poly_os) to avoid flicker. The blue and red objects also contain an experimental layer controll attribute (ATTR_layer_group. The red object has a layer number lower than airports, putting it under the runways, while the blue object contains a layer number higher than airports but lower than 3-d objects, guaranteeing that the yellow cube goes over it and not vice versa. Without these the load order would be random and every object would be on top of the runways.