Painted transparency with failures or limitations
Closed, ResolvedPublic


I note that the transparency of objects have some errors.
If Hide Backside is active the Grid disappears behind the object.
If Hide Backside is disabled some Backfaces overlap the object.
Volumetric Light is incompatible with transparencies.

This is by design. Without volume texture storing the volumetric properties it's impractical to render transparency with fog.
But the transparent objects should be visible without the fog effect applied on them.

The grid issue is because transparent object does not draw depth because of ordering issue. It's difficult to resolve without drawing multiple times.

Albert (wevon) added a comment.EditedTue, Jul 18, 12:36 PM

It is difficult to see in the second image, it shows how some Backfaces are painted erroneously above the faces oriented to camera.
I hang another image where it is better appreciated. The yellow and green grid material are the same. There are two objects to the left and one with two materials to the right. From above the transparency is seen correctly, from below the order of painting is reversed.

It's because transparency is order per object. Sorting pixels is too costly for realtime rendering.

Thanks for the aclaramient Clément.
From what I have seemed to appreciate the overlapping faces of the same object are sorted by identification number and by material. The materials under the pile are painted at the end (above).

That's correct. But it's not view dependent. So order can be wrong when changing viewing angle.