PxrTexture: Crash on focus

[brendanholt]

Version: Gaffer 1.6.7.0
Third-party tools: RenderMan 26.3
Third-party modules: N/A
OS: Rocky Linux 9.3

Description

Attempting to preview a PxrTexture node causes Gaffer to crash with minimal terminal output.

Steps to reproduce

1. Create a PxrTexture node.
2. Click the focus icon on the new texture node.
3. Boom.

Debug log

Although the viewport is set to OpenGL, it looks like Cycles is doing something just after I focus on PxrTexture.

Click to Expand

DEBUG : GafferScene::RendererAlgo : Unsupported data type for Context variable "image:defaultFormat" (GafferImage::FormatData), unable to add this variable to output image header
INFO : Cycles : Mem:0.000G, Peak:0.000G | Waiting for render to start
INFO : Cycles : Mem:0.000G, Peak:0.000G | Loading render kernels (may take a few minutes the first time)
INFO : Cycles : Mem:0.000G, Peak:0.000G | Updating Scene
INFO : Cycles : Mem:0.000G, Peak:0.000G | Updating Shaders
Segmentation fault (core dumped)

[murraystevenson]

The crash itself is in Cycles' ccl::OSLRenderServices::get_texture_info() and it looks like this is related to a Cycles bug that was fixed in https://projects.blender.org/blender/blender/pulls/136075. That fix was released in Cycles 4.5 but Gaffer 1.6 is on Cycles 4.4, though for Gaffer 1.7 we do plan to update Cycles.

You may well be thinking "Why is this RenderMan shader being previewed in Cycles?". In an environment without Arnold, Cycles will be used to visualise PxrTexture as it is an OSL shader. In an environment with Arnold you shouldn't see a crash as Arnold is used to visualise OSL shaders and it more gracefully handles gettextureinfo() being called on a missing image.

We haven't yet registered a ShaderView for previewing RenderMan shader balls as unlike our other supported renderers, RenderMan only supports a single render within the same process, so previewing a shader would prevent you from rendering interactively, and vice-versa. Despite that juggling it may be worth registering a RenderMan ShaderView in light of this crash...

[brendanholt]

Thanks for explaining what was going on, that all makes sense! I stumbled across this issue while trying to troubleshoot an unrelated problem. I can just avoid using the focus feature for now on PxrTexture nodes. It sounds like Gaffer 1.7 with newer Cycles will likely solve this issue anyway.