Transparent faces in mesh plots overlap incorrectly

Normally, when a face is opaque it can obscure other faces, or if the camera is rotated 180 degrees the first is now obscured by the second. This is currently not true for faces with opacity < 1. Instead it seems as if they are always layered in order of creation, so the first face in the mesh will always be on top (or beneath?) the others, no matter their relative 3D location.

The example contains 4 triangles: the two on the left are opaque while the two on the right are transparent.

• Notice how the orange face is always in front of the blue one, even though they intersect and part of it should be behind, as demonstrated by the purple and red triangles.
• Even if the camera is rotated.

https://codepen.io/anon/pen/bQqeMg

This leads to situations where obscured objects are drawn in front. All the boxes in the image below are either behind or inside the Blue one.

Observed in Chrome 70.0.3538.102 and Firefox 63.0.1 (64-bit) on Win 10

Commencez par la reproduction CodePen liée et exécutez-la dans Chrome ou Firefox. Comparez les triangles opaques et transparents qui se croisent en faisant pivoter la caméra, puis vérifiez que les faces transparentes sont ordonnées selon leur position 3D plutôt que selon leur ordre de création, et que les objets masqués ne sont plus rendus au premier plan.