[usdview] Difficult to differentiate imaging cachePath vs render index path

[moddyz]

Description of Issue

When debugging imaging problems via usdview, it is useful to print or inspect various scene or imaging paths at different locations in the codebase.

However, it is often difficult to distinguish between the types of paths (UsdPrim paths, cache paths, render index paths) by simply observing the value.

Notably, cache paths and render index paths have the exact same value in usdview, because its UsdImagingGLEngine member is constructed with an absolute root path ("/") as its delegateID.

It would be useful for a debug environment variable to have usdview construct UsdImagingGLEngine passing in a non absolute root path as its delegate ID (could be just something as simple as UsdImagingDelegate). That way, it becomes easier to distinguish different types of paths by observing their value.

System Information (OS, Hardware)

ubuntu-18.04

Package Versions

usd-19.11

Build Flags

Dynamic build.

[jilliene]

Filed as internal issue #USD-5807

[c64kernal]

Thanks for the report @moddyz -- we'll have a fix for this pushed up soon.

[moddyz]

Hey @c64kernal - did this fall off the radar? 😛

[c64kernal]

Hi @moddyz -- sorry about the lack of updates here. It's definitely not off the radar, what ended up landing in 20.05 and pushed up to dev, was a whole bunch of clean up to the way paths were handled (especially in the picking code) so that such a debug facility wouldn't need a bunch of special-casing everywhere. That all made it in already and will be in 20.05. So now what remains is a relatively small part that actually exposes and uses an env var. That's on deck for us right now. Props to @rajabala and @tcauchois for sorting through this stuff. As soon as that gets pushed to dev, this issue should get closed.

[moddyz]

That sounds awesome @c64kernal, thanks for the update. Really appreciate the clean-up around that area!

[c64kernal]

Hi @moddyz this should now be in place in the dev branch.

[moddyz]

@c64kernal sweeeet. This is going to be very useful for debugging purposes - will get it a test run, soon!

[moddyz]

Hey @c64kernal

Gave it a try. Working beautifully!

Hydra doesn't seem to like non-absolute path(s) supplied to USDIMAGINGGL_ENGINE_DEBUG_SCENE_DELEGATE_ID - but as it is a debug feature, and the errors are pretty obvious (for developers), I think it should be fine!

Thanks again!

[tcauchois]

@moddyz Please do file issues if you find the feature tripping up hydra or usdview!

[c64kernal]

+1 to what Tom said -- and glad the feature is working out for you, thanks again to @rajabala and @tcauchois for their work on it.