Feature request: Add support for self masking of semi-transparent materials.

[RedStoneMatt]

I have a fish model, with some parts of its texture being transparent:

The problem is, when these faces are put in front of other faces from the same object, the transparent part hides them instead of displaying over it:

This makes it impossible to look through the transparent part. This problem does not seem to happen when rendering the transparent faces over faces of a different object, but I can't just manually separate every single element into multiple objects because these models are automatically exported and there's 160 of them.

The model I used: Sardine.zip

[UX3D-hohenester]

In this instance you can easily fix the issue by using "MASK" as alpha blend mode in the transparent material.

[RedStoneMatt]

In this instance you can easily fix the issue by using "MASK" as alpha blend mode in the transparent material.

This isn't really a fix, it only works because this specific model's textures do not have important semi-transparent areas, but I've got 160 fish models and a lot of them do, in which case the MASK alpha blend mode will just erase half of it ^^'

[UX3D-hohenester]

That is unfortunate to hear. Unfortunately Sample Viewer does not yet support proper self masking for semi-transparent materials.
I've marked this issue as feature request (and also changed the title. Old title: "With a material using alpha BLEND mode, faces of an object will hide each other, even when there's transparency.")

Technical explanation:
Currently sample viewer handles transparency (for blend mode "BLEND") only on a node basis. Nodes are sorted according to their z-depth. The alpha blending is then performed based on that ordering. This is done for performance reasons (as far as i know babylon.js does more or less the same). Unfortunately this produces slightly wrong results in cases of self masking (as can be seen in your example).