blender/blender

Cycles: Ambient Occlusion not working with OptiX OSL #108992

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opened 2023-06-14 23:29:42 +02:00 by jack conradsen · 11 comments

jack conradsen commented

2023-06-14 23:29:42 +02:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 528.49

Blender Version
Broken: version: 3.5.0, branch: blender-v3.5-release, commit date: 2023-03-29 02:56, hash: 1be25cfff18b
Worked: (newest version of Blender that worked as expected)

Short description of error
I can't find much info on osl within blender. As i understand it, the point is to be able to write your own shaders with scripts, it shouldn't change the functionality of preexisting shader nodes.

Optix without OSL and CPU (with & without OSL) device renders darker droplets.

Exact steps for others to reproduce the error
In rendered view. Enable/disable OSL and see the water droplets look drasticly different (OSL looks more correct, but that should just be the default behavior then)

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3090/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 528.49 **Blender Version** Broken: version: 3.5.0, branch: blender-v3.5-release, commit date: 2023-03-29 02:56, hash: `1be25cfff18b` Worked: (newest version of Blender that worked as expected) **Short description of error** I can't find much info on osl within blender. As i understand it, the point is to be able to write your own shaders with scripts, it shouldn't change the functionality of preexisting shader nodes. Optix without OSL and CPU (with & without OSL) device renders darker droplets. **Exact steps for others to reproduce the error** In rendered view. Enable/disable OSL and see the water droplets look drasticly different (OSL looks more correct, but that should just be the default behavior then)

blender_fGjzru6h1o.gif

7.9 MiB

droplets.blend

9.3 MiB

jack conradsen added the

labels 2023-06-14 23:29:43 +02:00

jack conradsen changed title from ~~Enabling/disabling Open shading language changes the look of default shader nodes~~ to Enabling/disabling Open shading language changes the look of preexsting shader nodes

2023-06-14 23:29:59 +02:00

YimingWu added the

Render & Cycles

label 2023-06-15 04:06:31 +02:00

YimingWu commented

2023-06-15 04:09:51 +02:00

Member

Can't replicate the issue on CPU (my device doesn't have a GPU right now), the problem is probably limited to GPU, on CPU it looks like whether enabling OSL or not, it renders as the "darker droplets" result. Changing light path settings doesn't seem to improve the situation either.

Can't replicate the issue on CPU (my device doesn't have a GPU right now), the problem is probably limited to GPU, on CPU it looks like whether enabling OSL or not, it renders as the "darker droplets" result. Changing light path settings doesn't seem to improve the situation either. ![图片](/attachments/71b1ac4d-e1de-43ff-bb3e-17995effa6df)

25 KiB

Pratik Borhade commented

2023-06-15 05:53:09 +02:00

Member

I can confirm the difference with Optix OSL
Guess the dark droplets are due to intersection with pool? (#96475)

I can confirm the difference with Optix OSL Guess the dark droplets are due to intersection with pool? (#96475)

Pratik Borhade commented

2023-06-15 06:00:26 +02:00

Member

On previous versions, CPU (with & without OSL) and GPU rendering results are bit different

On previous versions, CPU (with & without OSL) and GPU rendering results are bit different ![image](/attachments/f2d7ac19-b450-4bac-80f8-4f091092c600)

1.3 MiB

Pratik Borhade changed title from ~~Enabling/disabling Open shading language changes the look of preexsting shader nodes~~ to Cycles: Enabling/disabling OSL changes the look of pre-existing shader nodes

2023-06-15 06:03:10 +02:00

Pratik Borhade added

Render & Cycles

and removed

labels 2023-06-15 06:05:06 +02:00

Brecht Van Lommel added

and removed

labels 2024-06-14 16:01:40 +02:00

Weizhen Huang commented

2024-08-19 18:20:45 +02:00

Member

The darker droplets is because you mix with black based on ambient occlusion, and the pool is occluded by the droplets

You can enable "Only Local" on the ambient occlusion node so the intersection with the droplets is ignored. Is that what you want?

As for the discrepancy w/wo OSL, if you choose OSL then all the shader nodes are implemented in OSL, not only the scripts you create. Probably the GPU OSL is not handling ambient occlusion correctly, but I don't have an OSL-compatible GPU to verify.

The darker droplets is because you mix with black based on ambient occlusion, and the pool is occluded by the droplets <img width="297" alt="image" src="attachments/0ce91947-aa7c-403a-90ad-c51c647d1618"> You can enable "Only Local" on the ambient occlusion node so the intersection with the droplets is ignored. Is that what you want? As for the discrepancy w/wo OSL, if you choose OSL then all the shader nodes are implemented in OSL, not only the scripts you create. Probably the GPU OSL is not handling ambient occlusion correctly, but I don't have an OSL-compatible GPU to verify.

260 KiB

Weizhen Huang added

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labels 2024-08-19 18:20:57 +02:00

jack conradsen commented

2024-08-19 19:13:28 +02:00

Author

i reported this a year ago so i do not know all the intricacies, but probably i didn't want ambient occlusion on the droplets, so i maybe made a mistake back then.

Regardless there probably shouldn't be any difference on existing nodes with/without osl, so if the difference is exclusively with Ambient Occlusion then that's the bug to fix i reckon

i reported this a year ago so i do not know all the intricacies, but probably i didn't want ambient occlusion on the droplets, so i maybe made a mistake back then. Regardless there probably shouldn't be any difference on existing nodes with/without osl, so if the difference is exclusively with Ambient Occlusion then that's the bug to fix i reckon

Weizhen Huang commented

2024-08-20 17:39:54 +02:00

Member

@Sergey @pmoursnv would you like to have a check if ambient occlusion is working correctly on OptiX OSL?

In the test scene, the contact area of the pool and the water droplets should be black due to ambient occlusion, but doesn't seem to be the case with OptiX OSL, at least at the time when the bug was reported.

@Sergey @pmoursnv would you like to have a check if ambient occlusion is working correctly on OptiX OSL? In the test scene, the contact area of the pool and the water droplets should be black due to ambient occlusion, but doesn't seem to be the case with OptiX OSL, at least at the time when the bug was reported.

Alaska commented

2024-08-21 16:14:30 +02:00

Member

@Sergey @pmoursnv would you like to have a check if ambient occlusion is working correctly on OptiX OSL?

OptiX OSL does not support the trace function needed for Ambient Occlusion to work. So the ambient occlusion node will always return a constant color (I can't remember if it's white or black)

The trace function is not functional. As a result of this, the Ambient Occlusion and Bevel nodes do not work.

https://docs.blender.org/manual/en/latest/render/shader_nodes/osl.html

> @Sergey @pmoursnv would you like to have a check if ambient occlusion is working correctly on OptiX OSL? OptiX OSL does not support the trace function needed for Ambient Occlusion to work. So the ambient occlusion node will always return a constant color (I can't remember if it's white or black) > The trace function is not functional. As a result of this, the Ambient Occlusion and Bevel nodes do not work. https://docs.blender.org/manual/en/latest/render/shader_nodes/osl.html

Patrick Mours commented

2024-08-21 17:15:15 +02:00

Member

Note that this is documented at https://docs.blender.org/manual/en/latest/render/shader_nodes/osl.html

Note that this is documented at https://docs.blender.org/manual/en/latest/render/shader_nodes/osl.html

Weizhen Huang commented

2024-08-21 17:22:19 +02:00

Member

@pmoursnv Is there plan to support this functionality at any point? If it's documented behaviour I'm not sure if I should close the report or change to Known Issue.

@pmoursnv Is there plan to support this functionality at any point? If it's documented behaviour I'm not sure if I should close the report or change to Known Issue.

Patrick Mours commented

2024-08-21 17:36:37 +02:00

Member

It wasn't really possible to support previously, since OSL generates code that calls its intrinsics (like texture("@ao", ...) or trace(...)) via normal CUDA function calls, but OptiX trace may only be called from OptiX callables.
Technically OptiX can automatically inline all code up to the trace call, so this can probably be reevaluated and made working now. No timeline though.
Previous reports regarding this (#104082, #108973) were closed for the time being.

It wasn't really possible to support previously, since OSL generates code that calls its intrinsics (like `texture("@ao", ...)` or `trace(...)`) via normal CUDA function calls, but OptiX trace may only be called from OptiX callables. Technically OptiX can automatically inline all code up to the trace call, so this can probably be reevaluated and made working now. No timeline though. Previous reports regarding this (#104082, #108973) were closed for the time being.

Weizhen Huang changed title from ~~Cycles: Enabling/disabling OSL changes the look of pre-existing shader nodes~~ to Cycles: Ambient Occlusion not working with OptiX OSL

2024-08-21 17:39:56 +02:00

Weizhen Huang commented

2024-08-21 17:40:47 +02:00

Member

I'll close this then.

I'll close this then.

Weizhen Huang closed this issue

2024-08-21 17:40:51 +02:00

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