Help Dynamic Rod Attachment Problem

[josemendez]

Perhaps I have misunderstood how pin constraints with constraint orientation should work? I would expect the rigidbody to be constrained to its initial orientation in relation to the rod.

This is the behavior I get with a new scene, default solver settings, and a default rod blueprint (only with resolution reduced slightly): https://share.getcloudapp.com/mXuGbOpj

Doesn't seem right. I can repro the problem by simply going to the SpringRod scene, replacing its blueprint with the "plectoneme", reassigning the attachments, and setting the load's rotation to zero.

Hi!

Could reproduce this, when very close to zero relative rotation between the attached particle and the attached object, the orientation constraint has a mathematical singularity that causes the object's rotation to be negated.

Will try to fix this for the next update, but it might take a while. Depending on how critical this is for your use case, one simple workaround is to attach the object to the other end of the rod. Since the relative rotation between particle and object in this case is -180º instead of 0º, it should work correctly. Simply offsetting the rotation (as you initially found out, by rotating the object 40º) should also circumvent it.

Thanks for the report!

kind regards,