Opencl GPU Compute Rendering Tiles Incorrectly For Mix Glass and Transparent Shaders When Hair is Present. #79724

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: AMD Radeon RX 5700 XT ATI Technologies Inc. 4.5.13596 Core Profile Context 20.Q2.1 27.20.1023.1001

Blender Version
Broken: version: 2.83.4, branch: master, commit date: 2020-08-05 06:00, hash: c113af8288

Short description of error
When rendering a mesh with another mesh inside of it and the mesh has a mix glass and transparent shader and there is hair present in the scene then the mesh with the mix glass shader will render incorrectly with opencl compute.

CPU Render:

CPU +GPU Render:

GPU Render:

Example Blend File:
tests.blend
Exact steps for others to reproduce the error
Render example Blend file with Opencl GPU and CPU and compare results.

OR

Add mix glass and transparent shader to default cube.
Add another cube and give it the default principled shader and scale the cube inside the the default one.
Add a plane and give it a Hair particle system and move it to the side.
Add an HDRI for some light.
Render cpu and opencl gpu and compare results.

Also deleting the hair or deleting the inside cube fixes the Issue.

Added subscriber: @gabe2252

Added subscriber: @iss

#50193 is very similar report, which I am able to reproduce, but I am not able to reproduce this one.

Which GPU did you use? I swapped my RX580 in and the issue went away. It only happens with my 5700xt. I think it's an issue with the drivers. I'll have to try all the different drivers on the amd website for this card.

RX550 so indeed this looks like driver issue

Alright, so the "recommend" driver has the issue worse with hair and the cube:

The "Optimal" driver crashes when compiling the render kernels and the "Pro" driver which I was using originally has the original issue I reported.

Added subscriber: @jshlxx

Can confirm. Happens also on my older driver 20.4.2 aswell as 20.Q2.1

version: 2.83.4, branch: master, commit date: 2020-08-05 06:00, hash: c113af8288, type: Release

system-info.txt

Added subscriber: @spiderh

Windows 10 Pro 64-bit
Intel i5-2500K
AMD Radeon 570RX
Blender 2.82a to 2.91.2

Same issue is here. This is not driver issue. I tested AMD 20.4.2 to 21.2.1 versions (plus PRO drivers) and same thing happen.

CPU + GPU

CPU

Blend File

AMD_Transparent_Bug_Report.blend

Added subscriber: @mano-wii

Changed status from 'Needs Triage' to: 'Confirmed'

I'm not sure if it's the same problem, but with the file attached by @spiderh the semitransparent material almost completely disappears on the OpenCL GPU.

Added subscriber: @Blendify

Changed status from 'Confirmed' to: 'Archived'

As a result of the Cycles-x changes in Blender 3.0, OpenCL support for Cycles has been removed and older versions will not receive bug fixes in regard to OpenCL rendering.
This is due to the combination of the limited features, driver bugs, and the stalled OpenCL standard making maintenance too difficult.

Blender is working with hardware vendors to bring back GPU rendering support for AMD and Intel GPUs, using others APIs.
Support for all major GPU vendors is an important goal but this goal might not be met for the upcoming 3.0 release.

Support for AMD cards is already in the works, for updates see #91571.

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Opencl GPU Compute Rendering Tiles Incorrectly For Mix Glass and Transparent Shaders When Hair is Present. #79724