Why does my model file entirely crash OpenSim / OpenSim Creator?

[adamkewley]

AK: this question was ported from an email. The content was edited/redacted to fit the discussions format.

I am attempting to use OpenSim Creator to build a new dinosaur model, having successfully used it in the past. However, both OpenSim and OpenSim Creator crash whenever I attempt to load my model or modify it. There is plenty of memory and it doesn't matter what computer I use, I get the same result (none). Is there a problem with the software?

[adamkewley]

If OpenSim or OpenSim Creator are otherwise fine, apart from your specific model file, it might be because the model is unusual enough to triggers bugs (e.g. segfaults) in OpenSim. The most common way this tends to happen is via the mesh importer, because it's streamlined enough to let you create elaborate graph cycles between joints.

Graph cycles are, in principle, supported, but when combined in weird ways can trigger bugs in OpenSim (e.g. #773). We are trying to fix some of these bugs, but they can be subtle, and related to how the underlying physics engine resolves relationships (e.g. opensim-core/#3697).

So my recommendation is that, if you have managed to create a model file that can hard-crash OpenSim and OpenSim Creator, it's probably related to graph cycles that are created when (e.g.) A joins to B joins to C joins to A joins to B... . Again, this should be supported, but if you are finding crashes and you don't want to wait for us to investigate why, I would recommend submitting your model file to OpenSim Creator's issues page, or opensim-core's issues page, followed by modifying your model to avoid cycles.