The question about m_normalWorldOnB

[Xuhai.Tang]

Hi,

I am trying to compute the force (F) at the contact point location. I define F=I*60, where I is the impulse. For the direction, I assign the normal to the master object (N):
N = m_normalWorldOnB
However, N is not always outward pointing. Does this make sense? Is there a better way of characterizing the force at the contact location?

Thanks in advance,
Xuhai

[Erwin Coumans]

The normal is pointing from object B towards object A.

If this is not the case, please provide a reproduction case.
Thanks,
Erwin

[Xuhai.Tang]

The normal is pointing from object B towards object A.

If this is not the case, please provide a reproduction case.
Thanks,
Erwin

Thank you.

I have found the reason.
(1) I changed ‘#define CONVEX_DISTANCE_MARGIN btScalar(0.04)’ to ‘#define CONVEX_DISTANCE_MARGIN btScalar(0.00)’.
(2) after the above change, the nornal is wrong when the distance between getPositionWorldOnA and getPositionWorldOnB is smaller than 10e-6.

By the way, what is differences between CONVEX_DISTANCE_MARGIN and m_collisionMargin in the btCompoundShape.h?

Thank you in advance
Xuhai Tang