Cycles doesn't render volumes when clip end is inside the volume #92789

New Issue

Sven Hinze · 2021-11-03T14:42:23+01:00

Sven Hinze commented

2021-11-03 14:42:23 +01:00

System Information
Operating system: Windows-10-10.0.19042-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.11

Blender Version
Broken: version: 3.1.0 Alpha, branch: arcpatch-D13070, commit date: 2021-11-02 14:29, hash: 53d54fc6a9
Worked: (newest version of Blender that worked as expected)

Short description of error
When clip end is set to a value inside a volume, the volume is not renderered at all.
Related to #92491 so an alpha build is needed.

Exact steps for others to reproduce the error

Open project
Press F12 (Volume isn't rendered)
Set clip end to something high (e.g. 100)
Press F12 again (Volume is rendered)

volume.blend

**System Information** Operating system: Windows-10-10.0.19042-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.11 **Blender Version** Broken: version: 3.1.0 Alpha, branch: arcpatch-[D13070](https://archive.blender.org/developer/D13070), commit date: 2021-11-02 14:29, hash: `53d54fc6a9` Worked: (newest version of Blender that worked as expected) **Short description of error** When clip end is set to a value inside a volume, the volume is not renderered at all. Related to [#92491 ](https://developer.blender.org/T92491) so an alpha build is needed. **Exact steps for others to reproduce the error** - Open project - Press F12 (Volume isn't rendered) - Set clip end to something high (e.g. 100) - Press F12 again (Volume is rendered) [volume.blend](https://archive.blender.org/developer/F11696788/volume.blend)

Sven Hinze commented

2021-11-03 14:42:23 +01:00

Added subscriber: @Sven-Hinze

Philipp Oeser commented

2021-11-03 16:03:44 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-11-03 16:03:44 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2021-11-03 16:03:44 +01:00

Can confirm the behavior (but that was the same before CyclesX, so behaves the same in 2.93.5 for me).

I guess #cycles devs needs to comment here (this might be expected behavior or have been reported before, cant find a duplicate though).

Can confirm the behavior (but that was the same before CyclesX, so behaves the same in 2.93.5 for me). I guess #cycles devs needs to comment here (this might be expected behavior or have been reported before, cant find a duplicate though).

Brecht Van Lommel commented

2021-11-05 18:35:21 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2021-11-05 18:35:21 +01:00

This is a known limitation right now.

It's due to the logic in volume_stack_clean, but we can't just remove that because it introduces other issues.

This is a known limitation right now. It's due to the logic in `volume_stack_clean`, but we can't just remove that because it introduces other issues.

Germano Cavalcante commented

2021-11-08 15:11:04 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Sven Hinze commented

2021-11-17 11:13:44 +01:00

@brecht Could you elaborate on this issue? I really need this functionality for my master's thesis and want to try to fix it myself.

Brecht Van Lommel commented

2021-11-17 13:32:22 +01:00

See the comment for volume_stack_clean:

/* Clean stack after the last bounce.
 *
 * It is expected that all volumes are closed manifolds, so at the time when ray
 * hits nothing (for example, it is a last bounce which goes to environment) the
 * only expected volume in the stack is the world's one. All the rest volume
 * entries should have been exited already.
 *
 * This isn't always true because of ray intersection precision issues, which
 * could lead us to an infinite non-world volume in the stack, causing render
 * artifacts.
 *
 * Use this function after the last bounce to get rid of all volumes apart from
 * the world's one after the last bounce to avoid render artifacts.
 */

See the comment for `volume_stack_clean`: ``` /* Clean stack after the last bounce. * * It is expected that all volumes are closed manifolds, so at the time when ray * hits nothing (for example, it is a last bounce which goes to environment) the * only expected volume in the stack is the world's one. All the rest volume * entries should have been exited already. * * This isn't always true because of ray intersection precision issues, which * could lead us to an infinite non-world volume in the stack, causing render * artifacts. * * Use this function after the last bounce to get rid of all volumes apart from * the world's one after the last bounce to avoid render artifacts. */ ```

Brecht Van Lommel commented

2021-11-17 13:33:46 +01:00

It's easy to just not use that function in a custom build, but we can't do that in regular builds without introducing problems.

Philipp Oeser removed the

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Cycles doesn't render volumes when clip end is inside the volume #92789