Why is is that PolySplit SOP often errors when a file is opened in newer version of Houdini ? This is a problem that has been around ever since I started using Houdini (version 7) and while I don't expect it to be fixed I would still like to know what are the reasons for that. Latest instance happened today when I attempted to open H20 file in H22. It opened fine in H20.

I’ve run into this before, and investigation showed the problem wasn't with the PolySplit node itself. During its operation, PolySplit writes a string into a parameter referencing specific polygon or half-edge IDs (or something similar). If the geometry topology changes upstream of the PolySplit, that string can become invalid, causing an error. Topology changes can occur if the algorithm of any node *before* the PolySplit is modified; even if things look fine on the surface, the polygon numbering has shifted, meaning any nodes relying on those specific IDs will malfunction. Newer versions likely improve algorithms but alter the numbering—it’s just the downside of a procedural workflow, I suppose. I think the best approach is to stash the models after a complex assembly process.

That would make a lot of sense but: whenever older file is opened in a newer version all the otl definitions are the version that is contemporary to Houdini version with which hip file was authored. However, if that was true PolySplit wouldn't error. I never had problem with any other node going out of whack. Also I just opened another hip I knew was problematic and error occurred right after another polysplit node.

If it's possible to share the file, we would be interesting in investigating the cause of the incompatibility.
Thanks,
Justin

Hi Justin,

Is it ok to message you a download link ?

Cheers !

kumpa
Hi Justin,

Is it ok to message you a download link ?

Cheers !

Sure! Thanks!