Controlling Draw Order

This article describes how you can control draw order inside a scenery pack.

= Draw Order Within an OBJ =

Draw order within an X-Plane object is deterministic - X-Plane always draws objects in the order of their command structure. Therefore you can control draw order using your 3-d modeling tool.


 * The ac3d exporter will export models in the order shown in the hierarchy view.
 * The Blender exporter will sort your model, but will keep groups separated, and will put mesh triangles marked "alpha" last.
 * LR's modified blender exporter for v10 (to be staged with v10 - contact LR if you want to merge the changes into another distro) sorts triangles back to front and front to back to help make translucent surfaces work.

X-Plane 10 Only: the order of additive LODs is not guaranteed; X-Plane may draw the LODs in any order.

= Layer Groups and Draw Order Between OBJs =

All art assets in X-Plane belong to a layer group. Layer groups are always drawn in order, but within a layer group the draw order is unpredictable. This means:
 * You can force one object to always be drawn before another by putting it in a lower layer group (using ATTR_layer_group).
 * You cannot dynamically change the draw order at runtime - you must pick which object is drawn first.
 * You cannot change the draw order based on camera angle.

Note that using layer groups disables X-Plane's ability to optimize object draw order for performance (because it forces a particular, possibly non-optimal draw order); use layer groups only where you must use them for correct visual output.