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View Full Version : IK Hell and then some



cesario1212
02-19-2003, 01:48 AM
Okay, here's the deal: I have a character who needs to have ye ol typical Ik setup in the legs so that the feet stay attachd to the ground. The setup is easy, and I've done it before (see www.evil-plan.com for the tutorial I'm using). My problem is the bone layout. The object is a hard object, so the bones must be placed in the key pivot areas so everything bends right. Therefore, the intial bend of the knee and calf bones is inverted, resulting in IK bends that go completely the wrong way. Even after setting angle limits and boosting the Goal strength to 1000, I got rid of "the jitters" but the leg would never bend in the right direction, unless in extreme circumstances.

I've tried setting up a bone layer above the other where the bones are mirrored along the Z so the Ik bends properly. I then have the first bone layer "channel followe" the second. The problem is, now the feet in the first layer don't follow the feet in the second layer because, due to the IK setup on the second layer bones, the feet never really rotate in the first place! If anyone can help me solve this IK nightmare, I would gladly appreciate it. I would try expressions, but I'm still such a newbie to expressions I have no clue how to go about doing it (and LW's expression builder is about as good as the LW manual...a VCR manual if you get my drift).

Art-man

TerryFord
02-19-2003, 05:28 AM
Not sure if this is related to your problem; IK on legs will sometimes cause the leg to lock straight at the knee when moving the foot goal (it shouldn't ever bend the wrong way if your limits are correct). The solution is to rotate the leg bones at the knee and hip on frame 0 (so the character looks like it's squatting slightly), this will cause the IK to favor those angles. You might find that adding a knee goal will help too.

Regards,
Terry

cesario1212
02-19-2003, 10:37 PM
Thanks much. Kind of a "duh!" moment for me :) I bent the legs and skelegons in modeler, and voila.