Cartographic Polygon editing crash - fabric only

[r-veenstra]

1. Start USD Composer (I used 2023.2.1) - build from commit d1b7ebc
2. Enable fabric
3. Add a Cartographic Polygon via the quick add menu
4. Select it
5. Click Edit Control Vertices
6. Click on the default ground plane to place a first point
7. OV should briefly hang then crash

Note: Does not crash when fabric disabled

cc @corybarr

[lilleyse]

This doesn't seem to happen for regular BasisCurves.

Maybe a reason for CesiumCartographicPolygon to have a rel to a BasisCurves prim instead of being a subclass.

[lilleyse]

Actually, it seems like both BasicCurves and CesiumCartographicPolygon are working in USD Composer 2023.2.2.

Still might be worth considering the rel approach if that improves the workflow or fixes other bugs.

CC #630 and #636

[corybarr]

This doesn't seem to happen for regular BasisCurves.

Maybe a reason for CesiumCartographicPolygon to have a rel to a BasisCurves prim instead of being a subclass.

Moving to a rel would also let us query any prim that has a points attr. I can image some hypothetical dataviz workflows where creating a BasisCurves would be more work than needed. Users wouldn't necessarily have to even know about a BasisCurves.

[r-veenstra]

• Editing an existing CesiumCartographicPolygon with Fabric enabled in 2023.2.2 does crash
• Editing an existing CesiumCartographicPolygon with Fabric disabled in 2023.2.2 does not crash
• Editing an existing BasisCurve with Fabric enabled in 2023.2.2 does not crash
• Editing an existing BasisCurve with Fabric disabled in 2023.2.2 does not crash

[r-veenstra]

@corybarr @lilleyse I can confirm that the original repro steps from this issue no longer cause a crash in 2023.2.2 with latest main 57fdeeebf7c47ed08282d981056be98eb72c49cb

[r-veenstra]

However, if I run the repro steps, save a USDA, and re-open the usda, I do get a crash

So it seems the issue is currently related to editing CesiumCartographicPolygons that have been loaded from a USDA, vs being freshly created.

[corybarr]

That's puzzling. It's strong evidence that we won't be able to fix the issue in our codebase, but let me see if I can did up any more precise info in some tests.

[corybarr]

I tested this with the absolute minimal inheritance example:

class CesiumBasisCurvesChildPrim "CesiumBasisCurvesChildPrim" (
    doc = """Test prim for inheritance crashes"""
    inherits = </BasisCurves>
    customData = {
        string className = "BasisCurvesChild"
    }
) {
}

With a raw BasisCurves I was able to create this with FSD enabled:

With a BasisCurvesChild it crashed. Aside from executing the prim's Define via our UI, the example bypasses our codebase. I think we should provide this minimal example to NVIDIA so they can reproduce.

[corybarr]

In the meantime, let's fall back to a rel. Agreed? @lilleyse @r-veenstra

[r-veenstra]

A rel that points to a BasisCurve with a GlobeAnchor added, yes?

[corybarr]

@r-veenstra Exactly

[r-veenstra]

@corybarr makes sense. It should also resolve #636