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View Full Version : how to plant hand of an ik arm?

gu3
04-10-2005, 03:08 AM
hopefully someone can give me a quick answer to this question. I know there is a pretty simple way to do this but I am having trouble figuring it out. I just need to have my character plant one hand on the ground whilst banging on the ground with the other hand. I am able to point constrain the ik handle so that it doesnt move around, but the wrist joint is still flopping all over the place and penetrating the ground. I know there is a way to just make the hand perfectly still without counter animating the wrist every other frame, so what am I missing?

thanks
Arcon
04-10-2005, 03:22 AM
constraints won't help a lot in this scenario - unless you use them in a broken-chain rig at the wrist... which i'm guessing you're not using. that would allow you to animate when the wrist inherits orientation from the joints above it, and when it just stays pointing in one direction which is what you would want when its planted.

basically you need at least one extra joint or null node [with an orient constraint] overlapping at the wrist joint, and make an attribute for it that blends the constraint on and off.

for more info try doing a search on broken chain rigs in the archives, and Paul G Thuriots DVD on hyper-realistic character rigging covers this quite well.
gu3
04-10-2005, 05:29 AM
oh yes, thats what I wanted to hear. So, it looks like if I parent the wrist joint to a null node, and then point contrain that node to the forearm, than I should be able to get what I need by just keying the weights of the constraint. I just did a quick test and its looking pretty good. Does that sound about right? Im guessing that it is not the perfect "broken rig" setup, but it seems like it might do for this one specific shot.

Thank you so much for your help!
Arcon
04-10-2005, 10:02 AM
anytime dude :)
cloudtrix
04-11-2005, 11:22 PM
anoter solution you might want to try is to set up the arm like a leg. Have one IK from the wrist to the shoulder and one on the hand joint. Parent both IK handles under a hand ctrl. group the hand ctrl to itself. Parent Constraint the group to the floor.
(The group is an extra node just incase you still wanted to do some extra motion with the hand ctrl)
Craiger
04-13-2005, 07:51 PM
put a locator in the position of your wrist when it is on the ground.. then orient constrain (with maintain offset turned on) your wrist controller to the locator, and key the BlendOrient on and off as you need it. that should to the trick.
jgibz
04-20-2005, 12:11 AM
Hi everyone,
I was having the same problem, I spent a long time looking for tutorials/ trying make my own broken setup, but nothing was working, so then I tried just orient constraining the wrist joint in the ik chain to the object the hand was resting on, and that worked, I could move the root control around, and the hand stayed where it was.
Pretty rough way to do it I guess, but it works :)
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04-20-2005, 12:11 AM
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