Questions about Biped

Bruno Afonseca

Hi there!
So, I have a biped character and I need his hands' IK to be constrained to a moving object.
But that's easy. I need it to let go from this object, be free for a little while and then hold on to another object which should drive it around just like the first one.
What's the best way to do this?

cryrid

Animating the constraint value works for some... what program?

monster

Since Biped can only follow one IK object you need to use a work around.
Create a Point object (in the helpers tab) and set that as the IK object.
Add a Link Constraint to the Point.
Animate the Point object to follow one object then the other, and just use planted keys on the biped to follow the point when necessary.

Bruno Afonseca

3ds max, using character studio. I'd just create a link constraint and animate it if I could, but Biped doesn't let me do that...

Mark Dygert

Yep, what monster said works, I've had to do it a few times.

Set your biped IK to use a helper object, link constrain the helper to whatever you need, whenever you need it.

I attachment constrain another helper to the surface of the object where the hand will connect. Then snap the hand helper to it.

It gets a little dicey if you go back and start fudging around with the animation on the objects after you've linked the hand helpers to the objects so be careful, that's also where the surface helper comes in handy.

Bruno Afonseca

It makes perfect sense to me, but I tried and couldn't make it work. I used link constrain on the helper, linked it to the object i wanted it to follow. Until this step everything works fine.
But then after some frames I link constrained this IK helper to another object (by using the options Link to World and Add Link on the motion tab). Did not work even though I linked it to something else, it'd still follow the first object I've linked it to. What am I doing wrong here?

monster

The link constraint is weird. It takes effect on the frame after you set it.

An alternative to the link constraint is to position and orient constrain the object and animate the constraint weighting. The only problem with this, unlike the link constraint, is that you can't move the helper, it's just stuck to the target.

Bruno Afonseca

I knew it'd take effect the frame after, but this time it's not taking any effect at all. Stays linked to the first object and never lets it go. Any ideas on this?
I'll try the second one anyway. The helper position doesn't matter too much in this case.

Mark Dygert

The link constraint is a bit buggy did you first link it to the world, then link it to object? Sometimes if you don't do that it will have trouble letting go of its attachment to the first object.