Bug when 0 gravity in root Node

[epernod]

Take for example the scene: Demos/Liver.scn
Change the gravity of the root node:

As soon as the simulation start, the liver disappears... No error message in the console, neither on the components.

Does someone has an idea?

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[epernod]

This bug has been introduce in the last month approx.

[hugtalbot]

Hi @epernod
Yes this is due to my PR #521 about the CG
My fix was wrong the PR #556 should fix it (you can give it a try!).

If I'm right, the problem was that with no gravity, there was no external forces applied and the b vector was null. Then, in CG, the denominator den=pMp where p=b at first iteration was therefore den=0. Finally, a division by 0 is done, generating NaN positions in the MO. That's why your liver disappears.

[damienmarchal]

The PR are merged...so it should work.

If it doesn't feel free to reopen if you still have the problem.
Thank you all for the bug report & solution.