Old bug - Viewport GPU rendering crashes.

[Sarah-C]

.blend file:
Any with more than a cube in it. Looks like it may need a few material nodes.

Steps to reproduce:
1: Select Lux Core Rendering.
2: Select GPU Viewport rendering.

Error message from Blender console:

Python backtrace

File "C:\Users\sarah\AppData\Roaming\Blender
Foundation\Blender\4.1\scripts\addons\BlendLuxCore\engine\viewport.py", line 13 in start_session

OS: Windows 10
Blender version: 4.1
LuxCore version: BlendLuxCore v2.9 alpha 1

---

Of note - a question?
Is this a "Won't fix" issue, due to the excessive physical delays in piping edited data back through to the GPU?
I've read a couple of posts where moving light meshes with GPU viewport rendering is very slow due to that overhead of recalculating lighting from the meshes and material changes and such?

(In other words - Is GPU viewport rendering a no-go because the render time saved by hardware acceleration is lost by the frequent scene changes when editing a scene?)

[neo2068]

Hi! I cannot reproduce the error. For me, GPU rendering works. Keep in mind, that for the first time, CUDA needs to comile the render kernel. This process needs several minutes to complete but this is a one time delay. Can you give more information on the used hardware and give a detailled error message?

[Sarah-C]

[JUST NOTICED this morning! A vital piece of information is missing! Sorry!
Creating a scene from scratch works FINE with GPU Viewport rendering.
I've been able to save and load it without issue.
But EVERY Lux Core example scene crashes when I've changed to GPU viewport render.
So this is a low priority little bug - so far only the example scenes crash the viewport render.
e.g. https://github.com/LuxCoreRender/LuxCoreTestScenes/releases/download/v2.3/ProceduralLeaves.zip
]

Thanks for having a look!

Keep in mind, that for the first time, CUDA needs to compile the render kernel.

I made sure to wait - it took a bit over 10 minutes. I made sure not to try clicking buttons or alt-tabbing out.

I've included the details for what I could find - but the error doesn't get very detailed from what I could see?
EXCEPTION_ACCESS_VIOLATION, pyluxcore.pyd line 13 in start_session.
The stack trace didn't mean much to me.

The full details are below, and in the crash.txt I included.

Graphics card: RTX2060

OS Name Microsoft Windows 10 Pro
Version 10.0.19042 Build 19042
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name HELLRAISER-4
System Manufacturer Dell Inc.
System Model OptiPlex 790
System Type x64-based PC
System SKU
Processor Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, 3401 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date Dell Inc. A18, 24/09/2013
SMBIOS Version 2.6
Embedded Controller Version 255.255
BIOS Mode Legacy
BaseBoard Manufacturer Dell Inc.
BaseBoard Product 0HY9JP
BaseBoard Version A00
Platform Role Desktop
Secure Boot State Unsupported
PCR7 Configuration Binding Not Possible
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume1
Locale United Kingdom
Hardware Abstraction Layer Version = "10.0.19041.488"
Username HELLRAISER-4\sarah
Time Zone GMT Summer Time
Installed Physical Memory (RAM) 32.0 GB
Total Physical Memory 32.0 GB
Available Physical Memory 19.5 GB
Total Virtual Memory 96.0 GB
Available Virtual Memory 78.5 GB
Page File Space 64.0 GB
Page File C:\pagefile.sys
Kernel DMA Protection Off
Virtualisation-based security Not enabled
Device Encryption Support Reasons for failed automatic device encryption: TPM is not usable, PCR7 binding is not supported, Hardware Security Test Interface failed and the device is not Modern Standby, Un-allowed DMA-capable bus/device(s) detected, TPM is not usable
Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualisation Enabled in Firmware Yes
Hyper-V - Data Execution Protection Yes

Blender: blender-4.1.1

Blender crash . txt:
ProceduralLeaves.crash.txt

[Sarah-C]

A bit more information:
Starting a scene from scratch - the GPU Viewport render is doing well.
I've tried adding things, alpha transparency, volumetrics, sun, spot, area lights, and moulding the cube (heh, GPU doesn't work with sculpting (it doesn't update the mesh) but I can guess why!)

Anyway - If I get it to crash, I'll report back and mention what crashed it!

I was unable to make it crash, even after adding many Lux Core models from the LoL.
I also saved and reloaded the scene - no issue with GPU Viewport rendering.

The ONLY time it crashes is when the Lux Core examples scenes are loaded!

[Sarah-C]

I've tried saving the Leaves example in 4.1.1, then reloading the scene. Hoping that it would "re-format" the internal data perhaps.

GPU Viewport rendering still crashes. Hmmm.

[Sarah-C]

Ok, so using the leaves scene, it only STOPS crashing when I delete 2 of the 3 leaves, all but the single material node of the texture and the Subsurf modifier, and all of the lights, background, and focus. It seems like there's multiple "issues" in the demo file that cause the GPU Viewport to bomb out.

I'm going to leave it here, because the demo scenes are only meant to be rendered and tinkered with, there's no big reason to use GPU rendering with them. =)

Close if you like!

[odil24]

Ok, so using the leaves scene, it only STOPS crashing when I delete 2 of the 3 leaves, all but the single material node of the texture and the Subsurf modifier, and all of the lights, background, and focus. It seems like there's multiple "issues" in the demo file that cause the GPU Viewport to bomb out.

I'm going to leave it here, because the demo scenes are only meant to be rendered and tinkered with, there's no big reason to use GPU rendering with them. =)

Close if you like!

Are you using this version?
https://github.com/LuxCoreRender/BlendLuxCore/releases/tag/blendluxcore_v2.9alpha1

[Sarah-C]

I am!

Additionally, I'm trying to download various files from years ago - the example files are old aren't they?
So far I've got one - and it renders with GPU Viewport fine.

LuxCoreRender/LuxCore#403 the file volCaustics.blend.gz from 2020 works fine in Path trace GPU mode too.

I wonder if it's all down to some issue with file format - moving from an old file save for the example files, straight to V2.9 Alpha 1?

[neo2068]

I tested the procedural leaves scene and it works with GPU rendering on my system. Is your scene the original one from the repository?

[Sarah-C]

I tested the procedural leaves scene and it works with GPU rendering on my system. Is your scene the original one from the repository?

Yes it is, directly from the site.

If this is just an odd edge case with my PC, I'm happy if it's closed? No point wasting time on an issue that's obscurely based on 1 hardware setup!