hard constraint with condir and dof

[thomash27]

(Apologize in advanced if this post bothers you, cause i've posted on sidefx forum, but no luck from that.)

What is up everyone, I've been working on rbd, and I have a question about hard constraint working with condir and condof.

I've set the
constraint type to "position"(means i want to constrain the position of the object)
condof to "1"(means free to move on a plane)
condir to (0, 1, 0)(means the normal of the plane)

so theoretically the object shouldn't move up and down since i've constrained the movement of position of the object on "X-Z plane", but why does the object still move up and down after i set the initial velocity to (0, 1, 0)(also there is a gravity node)

It confused me a lot, please help me with this problem, if i misinterpret anything(concepts) or did something wrong, please let me know, because with more time considering and trying with the problem, i found that maybe i have wrong concepts in my mind.(Maybe the degree of freedom concept, and i found that rotational and positional constraint might have to work together in order to get the positional constraint function correctly, not sure about that)

Thank you, really appreciate your help.

constraint.hipnc

Edited July 11, 2022 by thomash27

[Benyee]

first,the problem(probably a problem) can be solved by setting the 'rest length' of your hard constraint node to 0

just tell the solver to constraint pts to the plane exactly, if with some non zero tolerance the calculated result would be biased from plane by v/force factors