I’m wondering, how to properly animate say a hand with IK along an arc. As in the 12 principles of animation, arms are supposed to follow arcs. But if I keyframe 2 locations of the hand it will animate along a straight line. So what is the correct way to do it? Is there a constraint for this or say I have to make the hand follow a path. How is it done?
There is a “Follow Path” constraint, set this against the hand IK target. The Path must be a curve object, either Bezier or NURB. You can also keyframe the “Influence” of the constraint - 0 means inactive, 1 means active. To keyframe this, type in the value you want at the frame you want then RMB-Click and select “Insert Single Keyframe”. Don’t forget that if you want the constraint active from frame 100 to frame 200 and not outside this range, you keyframe 0 at frame 1, 0 at frame 99, 1 at frame 100, 1 at frame 200, 0 at frame 201, 0 at the last frame. You must click the “Animate Path” button - then keyframe values for the offset so the IK target moves along the curve.
Another option is to add a disconnected bone, maybe parented to your “root” bone so it moves with the character. This bone should be at the centre of the arc - then add a Child Off constraint to the hand IK bone with this new bone as the target. Again you can keyframe the Influence of the constraint - then just keyframe some rotations of the new bone and the hand will rotate with it when the influence is set to 1.
You can combine the two methods together, so you have a “free” bone moving along the curve, and always on the curve somewhere, then use a Child Of constraint on the hand IK and just keyframe the influence when you need it. Adding a Track To constraint can force the hand IK to always point towards another object - this could be used to simulate a twisting motion of the hand as it sweeps along the curve.
Hope this helps you!
Cheers, Clock.
PS. Practice this on a new blend file with just a couple of bones and a curve until you get the effect you want.
The simple answer is, don’t use IK. An FK rig would be better/easier to get that arc. This is one of the main reasons FK and IK controls and switches are available on well designed rigs. Having both allows you to use the best tool for the job while not constraining your choice to either. Check out the Rigify addon for a rig with these options and controls and the Animation Toolkit for a tutorial on how to animate IK/FK switching.
Good luck!
Ok, I will play around with these possibilities. I have another question. What is the most popular or best rigging setup, is it Rigify or BlenRig, or just plain Blender self-made rig, or some other? I want to develop a character for sale on a 3D marketplace site, and I want it to be in the most popular-best rig format.
My choice would be Rigify, but it is the only option I have explored.
Cheers, Clock.
The correct way is to just insert more keyframes and create the arcs yourself.
How is this method going to get you a perfect arc? Pictures please…
Cheers, Clock.