MPxGeometryOverride crashes during Parallel Evaluation

[bradley_henke]

Maya 2020.2, CentOs 7, GeForce GTX 1080 (nvidia driver 450.66)

I've been debugging with the devkit geometryOverrideExample1 example, and I think I have finally narrowed down the crash to the following circumstances:

1. Add a time attribute to GeometryOverrideExample1_shape and create an input connection from time1 (this is just to force the shape to participate in the EG)
2. requiresUpdateRenderItems() returns false
3. requiresGeometryUpdate returns true

I have managed to get about 9 different varieties of stack traces, but the most common seems to be a crash in:

OGS::Graphics::TraversalState::NewTraversalState(OGS::Objects::_ArrayList<OGS::Objects::UString*, OGS::Objects::NoLifetime<OGS::Objects::UString*> >*)

After trying to reproduce this issue with other devkit examples, I discovered that overriding isIndexingDirty() and setting it to false will avoid the crash.

I'm not using Evaluation Caching or VP2 Caching. At the moment I'm only interested in Parallel Evaluation. I think this combination is completely legitimate. For my use case I don't want to update my renderItems once they have been created, but I do expect the geometry to change. I may need to support animated topology, but I don't see how this could be problematic given that I'm not interested in using the caches.

I presume that this is a bug on Autodesk's side, but I'd love for someone to confirm this for me in case my paradigm is wrong.

[negow]

> Add a time attribute to GeometryOverrideExample1_shape 

Where can I find this example? From the documentation there are only two examples using this class, apiDirectionalLightShape and apiMeshShape

[bradley_henke]

I just tried to pull it up online, but I think the most recent update 2020.3 may have broken the documentation. You may still be able to find it in the maya 2020.2 devkit which is what I was using.

[negow]

Ah! Yes, there it was. Thanks 🙂