Cycles HIP RT principled hair BSDF issue #109421

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opened 2023-06-27 21:34:59 +02:00 by nathan · 5 comments

nathan commented

2023-06-27 21:34:59 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: AMD Radeon RX 6800 XT ATI Technologies Inc. 4.5.0 Core Profile Context 23.5.2.230523

Blender Version
Broken: version: 3.6.0, branch: blender-v3.6-release, commit date: 2023-06-27 08:08, hash: c7fc78b81ecb
Worked: (newest version of Blender that worked as expected)

Short description of error
When rendering any geometry with the Principled Hair BSDF shader, the geometry becomes transparent and/or white, in the viewport and in a render.

I've attached two images and a simple fur setup I used to make this example.

One image is with standard HIP rendering, which produces expected results, meaning the fur is orange-ish and the ball is about the same color with visible faces.
The other one is wrong, the UV Sphere is strangely transparent and the fur is white and transparent. It does make for an interesting result though.

Exact steps for others to reproduce the error
Create a simple hair setup and assign a principled hair shader to it and enable HIP RT and render the scene.
I've also attached the file I used to produce the comparison images

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: AMD Radeon RX 6800 XT ATI Technologies Inc. 4.5.0 Core Profile Context 23.5.2.230523 **Blender Version** Broken: version: 3.6.0, branch: blender-v3.6-release, commit date: 2023-06-27 08:08, hash: `c7fc78b81ecb` Worked: (newest version of Blender that worked as expected) **Short description of error** When rendering any geometry with the Principled Hair BSDF shader, the geometry becomes transparent and/or white, in the viewport and in a render. I've attached two images and a simple fur setup I used to make this example. - One image is with standard HIP rendering, which produces expected results, meaning the fur is orange-ish and the ball is about the same color with visible faces. - The other one is wrong, the UV Sphere is strangely transparent and the fur is white and transparent. It does make for an interesting result though. **Exact steps for others to reproduce the error** Create a simple hair setup and assign a principled hair shader to it and enable HIP RT and render the scene. I've also attached the file I used to produce the comparison images

HIP_RT_principled_hair.png

2.5 MiB

standard_HIP_principled_hair.png

3.0 MiB

hair test HIP RT.blend

1.4 MiB

nathan added the

labels 2023-06-27 21:34:59 +02:00

Iliya Katushenock added the

Render & Cycles

label 2023-06-27 21:37:45 +02:00

YimingWu referenced this issue

2023-06-28 04:47:20 +02:00

HIP related bugs #109431

Pratik Borhade commented

2023-06-29 07:24:58 +02:00

Member

Probably related to #109418

Probably related to #109418

Brecht Van Lommel changed title from ~~Render Issues with HIP RT and the Principled Hair BSDF Shader~~ to Cycles HIP RT principled hair BSDF issue

2023-07-04 14:05:59 +02:00

Brecht Van Lommel added

Render & Cycles

Needs Info from Developers

and removed

Render & Cycles

labels 2023-07-04 14:06:32 +02:00

Brecht Van Lommel commented

2023-07-04 14:06:37 +02:00

Owner

CC @BrianSavery @salipour.

CC @BrianSavery @salipour.

nathan referenced this issue

2023-07-06 20:00:05 +02:00

Cycles HIP RT glass BSDF artifacts #109418

Brian Savery (AMD) self-assigned this 2023-07-10 04:02:39 +02:00

Brian Savery (AMD) commented

2023-07-10 04:07:30 +02:00

Member

I noted on the Glass ticket that this change https://projects.blender.org/blender/blender/commit/4e104d77c701 seemed to be where it started. We'll test if that is the same here with this one.

I noted on the Glass ticket that this change https://projects.blender.org/blender/blender/commit/4e104d77c701 seemed to be where it started. We'll test if that is the same here with this one.

Brecht Van Lommel commented

2023-07-13 23:16:35 +02:00

Owner

This has the same root cause as #109418, see that issue for an explanation of the problem and solution.

This has the same root cause as #109418, see that issue for an explanation of the problem and solution.

Brecht Van Lommel closed this issue

2023-07-13 23:16:37 +02:00

Blender Bot added

and removed

Needs Info from Developers

labels 2023-07-13 23:16:39 +02:00

Brecht Van Lommel added

and removed

labels 2023-07-13 23:16:45 +02:00

Brian Savery (AMD) commented

2023-07-13 23:23:40 +02:00

Member

This should be fixed by #110073

My comment from the other issue:
TLDR: Kernels were not being updated when the code changed. #110073 fixes this. Use the nightly or 4.0 alpha build

Long version:
We did some testing and here's what we found:
3.6 release build from Blender.org - ARTIFACTS
3.6.1 build from blender.org - FINE
4.0 alpha build from blender.org - FINE
Local builds, 3.6 or 4.0 branch - FINE

It seemed like there was a bad kernel being built, either from a SDK mismatch or something else. @brecht figured out that the kernels were not being marked as "dirty" and rebuilt when the source for them changed. See #110073. So what happened here is @LukasStockner changed the kernel code but the HIPRT kernels were not rebuilt (not his fault at all), so they mismatched Blender.

At any rate thanks everyone for helping find this. You can use a nightly build of 3.6 or 4.0 alpha and should fix the issue.

This should be fixed by https://projects.blender.org/blender/blender/pulls/110073 My comment from the other issue: TLDR: Kernels were not being updated when the code changed. #110073 fixes this. Use the nightly or 4.0 alpha build Long version: We did some testing and here's what we found: 3.6 release build from Blender.org - ARTIFACTS 3.6.1 build from blender.org - FINE 4.0 alpha build from blender.org - FINE Local builds, 3.6 or 4.0 branch - FINE It seemed like there was a bad kernel being built, either from a SDK mismatch or something else. @brecht figured out that the kernels were not being marked as "dirty" and rebuilt when the source for them changed. See #110073. So what happened here is @LukasStockner changed the kernel code but the HIPRT kernels were not rebuilt (not his fault at all), so they mismatched Blender. At any rate thanks everyone for helping find this. You can use a nightly build of 3.6 or 4.0 alpha and should fix the issue.

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