Painted transparency with failures or limitations #52089

New Issue

Albert · 2017-07-17T12:00:19+02:00

Albert commented

2017-07-17 12:00:19 +02:00

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.

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. ![Transparent.jpeg](https://archive.blender.org/developer/F669851/Transparent.jpeg)

Albert commented

2017-07-17 12:00:19 +02:00

Changed status to: 'Open'

Albert commented

2017-07-17 12:00:19 +02:00

Added subscriber: @wevon-2

Clément Foucault was assigned by Dalai Felinto

2017-07-17 12:08:13 +02:00

Clément Foucault commented

2017-07-17 15:21:21 +02:00

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.

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.

blender-admin commented

2017-07-17 15:42:25 +02:00

This issue was referenced by fe8fc79cee

This issue was referenced by fe8fc79cee3647ab51c4587dfd279a815c93d062

Clément Foucault commented

2017-07-18 10:11:58 +02:00

Changed status from 'Open' to: 'Resolved'

Clément Foucault closed this issue

2017-07-18 10:11:58 +02:00

Albert commented

2017-07-18 12:36:04 +02:00

Trans.blend
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.

[Trans.blend](https://archive.blender.org/developer/F670790/Trans.blend) 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. ![Grid.jpeg](https://archive.blender.org/developer/F670785/Grid.jpeg)

Clément Foucault commented

2017-07-18 16:05:30 +02:00

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

Albert commented

2017-07-18 17:59:14 +02:00

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).

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).

Clément Foucault commented

2017-07-18 20:55:48 +02:00

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

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Painted transparency with failures or limitations #52089