ik chain

bix · Post by **bix** » Thu Sep 11, 2008 9:13 am

Hi
I would animate a person that is hanging for his feet using the dynamics... but I have a problem: is't possible to make one bone to be child of two bones in the same time ( the pelvis bone is child of the two haunch bones)
thankyou
fabrizio[/img]

slowtiger · Post by **slowtiger** » Thu Sep 11, 2008 9:25 am

No, bones can have only one parent (like modern families).

Best solution would be to duplicate the whole character and re-parent its bones.

bix · Post by **bix** » Thu Sep 11, 2008 10:13 am

Hi Slowtiger,
I don't understand... if I duplicate my character I've two IK that doesn't match and if they are dynamic they'll behave in a different way... maybe there is some thing that i don't understand.
thanks fabrizio

slowtiger · Post by **slowtiger** » Thu Sep 11, 2008 12:05 pm

You duplicate your character so you can switch between them in the same scene ... maybe he's hanging from a tree in the beginning, but walking on the ground in the end. That's why you may need both of them (you will switch their visibility at one point).

I thought re-parenting was a good trick because you don't lose your binding informations. But I forgot about the direction of the bones! So you have to erase the leg bones and create them again, this time starting from the feet (or any other attachment point - if your character hangs from his knees, that's the point).

bix · Post by **bix** » Thu Sep 11, 2008 12:49 pm

this is for switch between different constrain... i made a sketch for explain the problem, may I sent it to your email?
thanks
fabrizio[/img]

bix · Post by **bix** » Wed Sep 17, 2008 3:43 pm

I've upload the setup reference at this link
http://img261.imageshack.us/my.php?image=setupikzm3.jpg
the problem is have two parents for a child ik chain... or another trick
thanks
fabrizio

chucky · Post by **chucky** » Wed Sep 17, 2008 3:56 pm

maybe keep the ik in the normal direction, but add a new chain of bones that control the dangling which have no shapes attached, I might post an example in a minute or 7, (if it works)

slowtiger · Post by **slowtiger** » Wed Sep 17, 2008 4:18 pm

Ah! Now I get it.

I once had that problem with a character on a motorbike. The bike should vibrate visibly, but not the character. Both hands were on the handlebar and needed to vibrate, too.

I startet two bone chains. One for the character in the usual way, starting at the hips and including the forearms. The other for the bike, including both hands. Since he was wearing big gloves, it was easy to hide the "gap" between the two IK chains.

In your case I'd suggest to just leave that gap where your green arrow is. Both legs have bones which are attached to the root bone, but only one IK chain continues to the hip, the other just ends in the thigh. Some adjustments might be necessary in the final movement to hide that one leg isn't really attached to the hip.

chucky · Post by **chucky** » Wed Sep 17, 2008 4:26 pm

like this maybe?

The feet lock is dodgy but hey, what's new?
So is the loop I know, my bad.
Just put one or two extra bones in in the reverse chain order from the ceiling to his hips and hang him from this new and invisible appendage

bix · Post by **bix** » Wed Sep 17, 2008 5:36 pm

oh and you have parented the hip to the last bone of the "invisible chain"?
and have locked the feet bones?
nice!!! I'll try
thanks

chucky · Post by **chucky** » Wed Sep 17, 2008 5:47 pm

You got it bix,
No problem.
One thing is I did attach the last bone in the chain to the root bone of the whole skeleton which is at the hips.
You might like to try that for all your rigs, it really helps.