Getting force applied to a Kinematic object

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bsaund
Posts: 2
Joined: Mon Sep 04, 2017 9:31 pm

Getting force applied to a Kinematic object

Post by bsaund » Mon Sep 04, 2017 10:05 pm

My Question:
In bullet it is possible to get the force applied to a kinematics object?
Is it possible to get the force applied to the anchored nodes of a soft body?


My Setup:
I am simulating a robot manipulating a soft body (cloth). When grabbing the cloth, certain cloth nodes are anchored to the grippers.
I am primarily concerned with the cloth behavior and am assuming I can manipulate the grippers kinematically. However, I do want to know the force that the cloth applies on the grippers (both from gravity and from stretching). Since the grippers are kinematic, I suppose I actually want the force the cloth would apply to the grippers if the grippers were not kinematic.

btSoftBody::predictMotion resolves the soft-body impulses, which does apply an impulse to the anchored btRigidBody object. However, this is immediately ignored, as my grippers are kinematic, (and m_inverseMass==0).

I would prefer to keep the grippers as kinematic objects, and also not duplicate the soft body impulse/motion calculations in btSoftBody.

bsaund
Posts: 2
Joined: Mon Sep 04, 2017 9:31 pm

Re: Getting force applied to a Kinematic object

Post by bsaund » Tue Sep 05, 2017 9:13 pm

For now I have copied the code from btSoftBody::PSolve_Anchors into a separate callback.
It is less code duplication than I originally thought.

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