Cycles ray visibility broken in viewport #86917

New Issue

Georg K · 2021-03-25T01:54:25+01:00

Georg K commented

2021-03-25 01:54:25 +01:00

System Information
Operating system: Linux-5.11.6-1-MANJARO-x86_64-with-glibc2.33 64 Bits
Graphics card: AMD VERDE (DRM 2.50.0, 5.11.6-1-MANJARO, LLVM 11.1.0) AMD 4.5 (Core Profile) Mesa 20.3.4

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-03-22 17:02, hash: 62987a6f98, ray visibility is completely broken in 2.92
Worked: 2.91

Short description of error
While viewport rendering in Cycles, toggling most ray visibility option works only once, e.g. toggling off works instantly, but toggling on does not work until you leave Rendered viewport mode and start it again (in rare cases, off and back on works one time). So for every object it is only possible to toggle one option once, for further changes, viewport rendering has to be restarted.

Toggling 'Diffuse' seems to work better - sporadically, 'Transmission' seems like it does not work at all (also in F12 rendering).
Factory settings did not help. I can't render with my GPU, so I can only speak for CPU rendering.

Exact steps for others to reproduce the error
In the test file RayVisibiliy_bug.blend, toggle off Camera/Glossy/VolumeScatter (please increase Volume Bounces in lightpaths)/Shadow on the respective objects and try toggling it back on - it does not work unless you leave Rendered viewport mode and start it again.

**System Information** Operating system: Linux-5.11.6-1-MANJARO-x86_64-with-glibc2.33 64 Bits Graphics card: AMD VERDE (DRM 2.50.0, 5.11.6-1-MANJARO, LLVM 11.1.0) AMD 4.5 (Core Profile) Mesa 20.3.4 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-03-22 17:02, hash: `62987a6f98`, ray visibility is completely broken in 2.92 Worked: 2.91 **Short description of error** While viewport rendering in Cycles, toggling most ray visibility option works only once, e.g. toggling off works instantly, but toggling on does not work until you leave Rendered viewport mode and start it again (in rare cases, off and back on works one time). So for every object it is only possible to toggle one option once, for further changes, viewport rendering has to be restarted. Toggling 'Diffuse' seems to work better - sporadically, 'Transmission' seems like it does not work at all (also in F12 rendering). Factory settings did not help. I can't render with my GPU, so I can only speak for CPU rendering. **Exact steps for others to reproduce the error** In the test file [RayVisibiliy_bug.blend](https://archive.blender.org/developer/F8833658/RayVisibiliy_bug.blend), toggle off Camera/Glossy/VolumeScatter (please increase Volume Bounces in lightpaths)/Shadow on the respective objects and try toggling it back on - it does not work unless you leave Rendered viewport mode and start it again.

Georg K commented

2021-03-25 01:54:25 +01:00

Added subscriber: @georgK

Philipp Oeser commented

2021-03-25 16:21:33 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2021-03-25 16:21:33 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philipp Oeser commented

2021-03-25 16:21:33 +01:00

Can reproduce in 54bbaa26de, but not in 9ac7946dd0.
(strange thing is I dont see a particular commit that could have fixed this, but can bisect...)

For the time being: could you check the latest build from https://builder.blender.org/download/?

Can reproduce in 54bbaa26de, but not in 9ac7946dd0. (strange thing is I dont see a particular commit that could have fixed this, but can bisect...) For the time being: could you check the latest build from https://builder.blender.org/download/?

Georg K commented

2021-03-25 16:38:36 +01:00

Camera/Diffuse/Glossy/Shadow are fixed in version: 2.93.0 Alpha, branch: master, commit date: 2021-03-25 15:06, hash: 5ebe74e779
but Transmission and Volume Scatter toggles don't seem to have an effect.

Camera/Diffuse/Glossy/Shadow are fixed in version: 2.93.0 Alpha, branch: master, commit date: 2021-03-25 15:06, hash: `5ebe74e779` but Transmission and Volume Scatter toggles don't seem to have an effect.

Philipp Oeser commented

2021-03-25 16:46:37 +01:00

Transmission works for me, Volume Scatter I am not sure about tbh (how would I best check the effect in provided .blend?)

Georg K commented

2021-03-25 17:46:10 +01:00

So there is a visible change if you switch off Transmission on the plane above the cube? To me, it looks completely identical even in a F12 render.

To test Volume Scatter, raise Volume Bounces in Light Paths, select the cuboid ("Cube.001") in front of the big cube and turn off Volume Scatter. If deactivating worked, the volume would stop looking like a white rectangular cloud when the light is bouncing inside. I am also not completely sure about this since I can't find a blender version where deactivating Volume scatter had an effect (even in a F12 render), but there has to be one (perhaps similar to the look if Volume Bounces is at 0 - overall grey).

So there is a visible change if you switch off Transmission on the plane above the cube? To me, it looks completely identical even in a F12 render. To test Volume Scatter, raise Volume Bounces in Light Paths, select the cuboid ("Cube.001") in front of the big cube and turn off Volume Scatter. If deactivating worked, the volume would stop looking like a white rectangular cloud when the light is bouncing inside. I am also not completely sure about this since I can't find a blender version where deactivating Volume scatter had an effect (even in a F12 render), but there has to be one (perhaps similar to the look if Volume Bounces is at 0 - overall grey).

Georg K commented

2021-03-25 18:28:10 +01:00

New testscene: the selected objects (".. receiver") should receive Volume Scatter/Transmission rays and therefore be lit if the respective toggles are on. If the toggles are off, the selected objects should not receive light.
RayVisibiliy_VolumeScatter,Transmission_bug.blend
To me it always looks like this:

But if Transmission and Volume Scatter are off, I would expect it to look something like this:

New testscene: the selected objects (".. receiver") should receive Volume Scatter/Transmission rays and therefore be lit if the respective toggles are on. If the toggles are off, the selected objects should not receive light. [RayVisibiliy_VolumeScatter,Transmission_bug.blend](https://archive.blender.org/developer/F9909613/RayVisibiliy_VolumeScatter_Transmission_bug.blend) To me it always looks like this: ![RayVisibiliy_VolumeScatter,Transmission_bug.jpg](https://archive.blender.org/developer/F9909617/RayVisibiliy_VolumeScatter_Transmission_bug.jpg) But if Transmission and Volume Scatter are off, I would expect it to look something like this: ![RayVisibiliy_VolumeScatter,Transmission_bug - expected result (off state).jpg](https://archive.blender.org/developer/F9909619/RayVisibiliy_VolumeScatter_Transmission_bug_-_expected_result__off_state_.jpg)

Philipp Oeser commented

2021-03-26 09:56:39 +01:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Philipp Oeser commented

2021-03-26 10:07:11 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philipp Oeser commented

2021-03-26 10:07:11 +01:00

reg. transmission in your file:

the upper plane is using a translucent BSDF, this I think is using diffuse rays for backface shading (not transmission), so turning OFF Diffuse ray visibility on the lower plane will make a difference.

reg. volume scatter in your file:

I dont understand the example, none of the participating objects use a volume shader, so where would the change of visibility take place?

reg. transmission in your file: - the upper plane is using a translucent BSDF, this I think is using diffuse rays for backface shading (not transmission), so turning OFF Diffuse ray visibility on the lower plane will make a difference. reg. volume scatter in your file: - I dont understand the example, none of the participating objects use a volume shader, so where would the change of visibility take place?

Georg K commented

2021-03-26 11:11:52 +01:00

Transmission:
On the right, both planes get darker if I deactivate diffuse on the lower plane because the light does not bounce back towards the upper plane and the camera, I believe.
Unfortunately, transmission is only vaguely defined in the blender wiki as "Transmission: the ray is generated by a transmission through a surface.", that is all I know, so I expect transparency and translucency to create transmission samples, but both do not react to the transmission ray visibility.
If you change the translucent shader on the upper plane to a transparent shader, then toggling transmission (on the upper or lower plane) also has no effect.

Volume Scatter:
If you select "Scattering Volume" it does have a volume shader.
The cube on the left has two intersecting ducts, one vertical containing the light and one horizontal, containing the scattering volume. With scattering off, the light goes mainly down along the vertical duct to the bottom plane. It should bounce only very slightly through the horizontal duct - similar to how it looks if you hide the "Scattering Volume" object.
If scattering is active, the scattering volume in the horizontal duct helps the light to travel to both planes at the sides.

Transmission: On the right, both planes get darker if I deactivate diffuse on the lower plane because the light does not bounce back towards the upper plane and the camera, I believe. Unfortunately, transmission is only vaguely defined in the blender wiki as "Transmission: the ray is generated by a transmission through a surface.", that is all I know, so I expect transparency and translucency to create transmission samples, but both do not react to the transmission ray visibility. If you change the translucent shader on the upper plane to a transparent shader, then toggling transmission (on the upper or lower plane) also has no effect. Volume Scatter: If you select "Scattering Volume" it does have a volume shader. The cube on the left has two intersecting ducts, one vertical containing the light and one horizontal, containing the scattering volume. With scattering off, the light goes mainly down along the vertical duct to the bottom plane. It should bounce only very slightly through the horizontal duct - similar to how it looks if you hide the "Scattering Volume" object. If scattering is active, the scattering volume in the horizontal duct helps the light to travel to both planes at the sides.

Philipp Oeser commented

2021-03-31 09:45:01 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Philipp Oeser commented

2022-02-11 12:30:36 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philipp Oeser commented

2022-02-11 12:30:36 +01:00

Coming back to this (sorry this slipped under the radar):

reg. Transmission: my explanation is as follows:

camera ray hits Transmission receiver, has a diifuse shader, fires a diffuse ray, then hits Transmission
- for this diffuse ray, it is visible
turning OFF Transmission ray for Transmission visibility would only come relevant if we'd have a transmissive object (such as Glass or Principled with transmission above 0) that is e.g. in front of it
- this first gets hit by a camera ray, would then fire a transmission ray and for that ray Transmission would then be invisible

similar for the volume scatter case:

this would work if the "stick" object would get hit by a volume scattering ray, so in this case the bigger cube should have the volume scattering shader, which then sends those rays and the stick could be made invisible to those rays.

Makes sense?

Coming back to this (sorry this slipped under the radar): reg. Transmission: my explanation is as follows: - camera ray hits `Transmission receiver`, has a diifuse shader, fires a diffuse ray, then hits `Transmission` - for this diffuse ray, it is visible - turning OFF Transmission ray for `Transmission` visibility would only come relevant if we'd have a transmissive object (such as Glass or Principled with transmission above 0) that is e.g. in front of it - this first gets hit by a camera ray, would then fire a transmission ray and for that ray `Transmission` would then be invisible similar for the volume scatter case: - this would work if the "stick" object would get hit by a volume scattering ray, so in this case the bigger cube should have the volume scattering shader, which then sends those rays and the stick could be made invisible to those rays. Makes sense?

Philipp Oeser commented

2022-03-24 13:29:47 +01:00

Changed status from 'Needs User Info' to: 'Archived'

Philipp Oeser closed this issue

2022-03-24 13:29:47 +01:00

Philipp Oeser commented

2022-03-24 13:29:47 +01:00

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed.

Thanks again for the report. If the problem persists please open a new report with the required information.

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed. Thanks again for the report. If the problem persists please open a new report with the required information.

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Cycles ray visibility broken in viewport #86917