3D draw order incorrect with transparent surfaces

[slishak]

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

Setting all trace opacities in the above codepen to 1, all surfaces and scatter3ds are drawn in the correct order (when looking from above I can only see the blue surface, when looking from below only the red surface).

Setting the opacities to 0.999, the draw order seems solely determined by the order in which the traces were defined (so the red surface, which is defined first, is always occluded by the blue surface and all scatter3ds).

Transparent lines with opaque surfaces seem to be drawn correctly.

[etpinard]

Essentially a duplicate of #3243

Thanks for the very clear report!

[slishak]

Ah sorry, didn't find that open issue! :)

[etpinard]

No worries!