ObjectTalk crashes under Windows 11 + NVidia GT710

[Rithdev]

A quick summary and/or background:

The ObjectTalk IDE crashes when trying to start the Scene editor.

Steps to reproduce (be specific and give sample code if you can)

Compile the application.
Execute the binary/let Visual Studio open it under any configuration (Release/Debug).
Try to open the Scene Editor.
If running under Visual Studio debug tools, an exception is raised.
If running standalone, it returns the following.
2026-04-21 10-33-17.359 [fatal] OtComputePipeline.cpp (83): Error in SDL_ShaderCross_CompileComputePipelineFromSPIRV: SDL_ShaderCross_INTERNAL_CreateShaderFromSPIRV: Unexpected SDL_GPUBackend

What you expected would happen:

The scene editor opens.

What actually happens:

The application crashes under a SDL exception.

Notes (possibly including why you think this might be happening, or stuff you tried that didn't work):

I have to note that this gpu has been abandoned by Nvidia for a long time, the latest available driver was released around ~2020, but similar crash reports of other type of applications under SDL are quite rare...

These are the applications logs under the debug build.

Available GPU Driver 1. direct3d12
Available GPU Driver 2. vulkan
WARNING: WinPixEventRuntime.dll is not available. It is required for SDL_Push/PopGPUDebugGroup and SDL_InsertGPUDebugLabel to function correctly. See here for instructions on how to obtain it: https://devblogs.microsoft.com/pix/winpixeventruntime/
SDL_GPU Driver: D3D12
D3D12 Adapter: NVIDIA GeForce GT 710
D3D12 Driver: 27.21.14.5671
Validation layers enabled, expect debug level performance!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
WARNING: Texture upload row pitch not aligned to 256 bytes! This is suboptimal on D3D12!
2026-04-21 10-40-28.069 [fatal] OtComputePipeline.cpp (83): Error in SDL_ShaderCross_CompileComputePipelineFromSPIRV: SDL_ShaderCross_INTERNAL_CreateShaderFromSPIRV: Unexpected SDL_GPUBackend

I haven't tried vulkan, as no matter of environment variables are able to make sdl run under vulkan rather than d3d12, if you have a flag, I'd love to try vulkan instead.

Running ot with --log only throws the following in the log file:
2026-04-21 10-48-24.497 [fatal] OtComputePipeline.cpp (83): Error in SDL_ShaderCross_CompileComputePipelineFromSPIRV: SDL_ShaderCross_INTERNAL_CreateShaderFromSPIRV: Unexpected SDL_GPUBackend

[goossens]

Thanks for the report. This has been a passion project for me for a long time and you are the first to create an issue. Congratulations! Your issue shows that I mainly develop on MacOS, ensure it compiles on Linux and Windows (using a virtual machine) and test it on Linux as the virtual machine supports Vulkan. Unfortunately, my VM does not support Direct3d12 so I can't test Windows since SDL GPU has Direct3d12 as a minimum. My PC went up in smoke late last year so I was waiting for prices to come down a little on PC parts. I don't think however that the AI stupidity bubble isn't going to burst anytime soon so your issue is triggering me to just bite the bullet and get a low end test PC.

Having said all of that, I did find some bugs in my code and I would really appreciate it if you could test the updated direct3d12 backend.

I've also added a command line flag (--vulkan) to force the use of the Vulkan backend on Windows so you can try that as well.

Let me know how that goes.