Cycles HIP RT glass BSDF artifacts #109418

New Issue

Philipp-Munkes · 2023-06-27T20:37:49+02:00

Philipp-Munkes commented

2023-06-27 20:37:49 +02:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: AMD Radeon RX 7900 XTX 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: Unknown

Short description of error
Rendering Pavillon Barcelona with HIP RT causes the water surface to be rendered incorrectly:

It renders correctly with HIP:

Exact steps for others to reproduce the error

Simply open the blender file here and render it with HIP RT.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: AMD Radeon RX 7900 XTX 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: Unknown **Short description of error** Rendering Pavillon Barcelona with HIP RT causes the water surface to be rendered incorrectly: ![grafik](/attachments/5c9df395-bb96-47bf-9f95-5360533c4492) It renders correctly with HIP: ![grafik](/attachments/ebc2e9d8-41bd-4f5f-a798-8ca12dfa81c9) **Exact steps for others to reproduce the error** Simply open the blender file [here](https://download.blender.org/demo/test/pabellon_barcelona_v1.scene_.zip) and render it with HIP RT.

grafik.png

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grafik.png

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system-info.txt

15 KiB

Philipp-Munkes added the

labels 2023-06-27 20:37:50 +02:00

YimingWu referenced this issue

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

HIP related bugs #109431

Pratik Borhade referenced this issue

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

Cycles HIP RT principled hair BSDF issue #109421

nathan commented

2023-06-29 19:17:45 +02:00

I can confirm this behavior with an RX 6800 XT.
After further testing, I found that the Glass BSDF shader is broken. Replacing the glass shader with a Principled BSDF fixes the issue with some minor visual changes.

HIP RT with Glass BSDF Shader

HIP RT with Principled BSDF Shader and the same roughness, IOR and color

I can confirm this behavior with an RX 6800 XT. After further testing, I found that the Glass BSDF shader is broken. Replacing the glass shader with a Principled BSDF fixes the issue with some minor visual changes. HIP RT with Glass BSDF Shader [![pavilion_barcelona_rt_glass.jpg](/attachments/842798af-088b-4cec-980d-b398ddc632c6)](url) HIP RT with Principled BSDF Shader and the same roughness, IOR and color [![pavilion_barcelona_rt_principled.jpg](/attachments/6fb97876-f299-4a8d-a51a-a2444e49cd4e)](url)

pavilion_barcelona_rt_glass.jpg

204 KiB

pavilion_barcelona_rt_principled.jpg

181 KiB

Brecht Van Lommel changed title from ~~Render Issue with HIP RT in Pavillon Barcelona~~ to Cycles HIP RT glass BSDF artifacts

2023-07-04 14:05:03 +02:00

Brecht Van Lommel added

Module

Render & Cycles

Status

Needs Info from Developers

and removed

labels 2023-07-04 14:05:21 +02:00

Brecht Van Lommel commented

2023-07-04 14:05:28 +02:00

CC @BrianSavery @salipour.

Brian Savery (AMD) commented

2023-07-06 05:31:30 +02:00

Does it work correctly with this driver? https://www.amd.com/en/support/kb/release-notes/rn-rad-win-22-40-51-06-blender-3-6-beta

nathan commented

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

The driver does not fix the issue
It also didn't fix the issue in #109421

The driver does not fix the issue It also didn't fix the issue in #109421 ![image](/attachments/6c86452a-25fb-4b08-9ef4-76f8a534bc76)

image.png

1.9 MiB

Brian Savery (AMD) commented

2023-07-10 04:05:48 +02:00

Our QA did some bisection, it looks like the issue cropped up after this change: https://projects.blender.org/blender/blender/commit/4e104d77c701 @LukasStockner tagging you here as well. Do you have any insight?

So we need to figure out if there is some AMD side compiler issue or what with that.

Our QA did some bisection, it looks like the issue cropped up after this change: https://projects.blender.org/blender/blender/commit/4e104d77c701 @LukasStockner tagging you here as well. Do you have any insight? So we need to figure out if there is some AMD side compiler issue or what with that.

Brian Savery (AMD) self-assigned this 2023-07-10 04:06:38 +02:00

Brecht Van Lommel commented

2023-07-10 15:07:48 +02:00

Looking at this commit, I don't see anything new that should cause this. Since it works on other GPUs, if it's a bug in the Cycles code I would expect an uninitialized variable or other undefined behavior, or maybe some difference in math functions or other HIP abstraction. But it's not clear to me where that would happen in this commit, I could not find a likely cause.

So I suspect a compiler bug, but it's difficult to be sure.

To pinpoint the exact cause, I think the next step is to "bisect" the code changes in this commit, to identify exactly which ones cause this.

Looking at this commit, I don't see anything new that should cause this. Since it works on other GPUs, if it's a bug in the Cycles code I would expect an uninitialized variable or other undefined behavior, or maybe some difference in math functions or other HIP abstraction. But it's not clear to me where that would happen in this commit, I could not find a likely cause. So I suspect a compiler bug, but it's difficult to be sure. To pinpoint the exact cause, I think the next step is to "bisect" the code changes in this commit, to identify exactly which ones cause this.

~~Brecht Van Lommel referenced this issue 2023-07-13 19:44:00 +02:00~~

Fix Cycles HIP RT kernel not rebuilding on changes #110073

Brecht Van Lommel referenced this issue

2023-07-13 20:20:28 +02:00

Fix Cycles HIP RT kernel not rebuilding on changes #110073

Brecht Van Lommel referenced this issue from a commit

2023-07-13 23:08:20 +02:00

Fix Cycles HIP RT kernel not rebuilding on changes

Brian Savery (AMD) commented

2023-07-13 23:10:35 +02:00

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.

TLDR: Kernels were not being updated when the code changed. https://projects.blender.org/blender/blender/pulls/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 https://projects.blender.org/blender/blender/pulls/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.

Brecht Van Lommel referenced this issue from a commit

2023-07-13 23:12:15 +02:00

Fix Cycles HIP RT kernel not rebuilding on changes

Brecht Van Lommel referenced this issue

2023-07-13 23:14:08 +02:00

Blender LTS: Maintenance Task 3.6 #109399

Brecht Van Lommel commented

2023-07-13 23:14:58 +02:00

Indeed, thanks everyone for investigating this.

Brecht Van Lommel closed this issue

2023-07-13 23:15:01 +02:00

Blender Bot added