Intercept crease weight exceptions and rethrow them with prim path

[EmilDohne]

Summary

While debugging an issue with an artist scene I ran across the following error message raised by cortex which was not very clear:

Bad creases : id (18476) is out of expected range (0-18338)

This exception is raised by cortex here and it would be fantastic if the calling code could intercept these to add information to which primitive is causing issues.

From what I can tell gaffer only calls this function here which should have access to this information.

Thanks in advance!

[johnhaddon]

I think we should try to deal with this a little more generically, so it covers any error thrown by a scene node. We already have some prior art for something similar in the ProcessMessageHandler, which adds path information to messages :

https://github.com/GafferHQ/gaffer/blob/main/src/Gaffer/ProcessMessageHandler.cpp

I pushed for that to very conservatively only output DEBUG level information, but with hindsight I think I was wrong : it would be useful to have this as a matter of course at WARNING level.

@EmilDohne, where in Gaffer do you need to see this information? In the GUI? In farm logs when running gaffer execute? Both? Anywhere else?

[EmilDohne]

I agree that a generic solution would be better and wouldn't be a cat and mouse game of implementing these. Personally a console log is more than fine fine as that is where I (as a pipeline td) will most of the time be looking.

If I understand correctly this would essentially intercept the exception, log a message and then let it bubble up?

[johnhaddon]

If I understand correctly this would essentially intercept the exception, log a message and then let it bubble up?

Yep, that's one option. Another is to improve the reporting at the point the exception bubbles out at the top - the exception contains the Gaffer Context object, so should have the information we need to print the path. If we take that approach, we should be able to improve the error tooltips in the GraphEditor too.