Keep one foot on the ground while moving hip

3dOutlaw

Is there a way to "lock" a leg from moving (i.e.its the one going to hold him up) while bending/rotating the hip? Basically making a move of bending to the side on one leg.

For example, if I am making a animation for a character to do this: http://www.santosha.com/assets/images/ekapada-kj-g.gif

...I want to fix that one leg, but bend the hip...let the other leg and top follow the hip...without that foot moving from the ground.

3dOutlaw

Here was one idea, that seemed to fail: Create a cube, place it under that foot, parent it to the foot, select the thigh, create IK chain by selecting the cube, and then make sure the leg moves using the IK chain...

Failed. Not sure why, but the leg did not move at all, when moving the IK Target. I was following this tut: http://www.youtube.com/watch?v=fPbMUJIkIkw

I figured if I got the thigh and the rest of the leg locked to an IK target, I could move the hip, and the leg would stay on the ground. :(

3dOutlaw

Correction, it worked. :) I had accidentally locked the leg movement in prior tests...I changed to ball joint and no problems!

3dOutlaw

Almost worked...I can't get the block and the foot to not move when I rotate the hip. I have added a Lock constraint on the movement (of foot, cube and IK Target), but that does not work.

Fenric

Carrara doesn't do Forward Kinematics (which is what you are asking for), only Inverse Kinematics where you move the endpoint.

What you need to do is to move the foot that is supposed to be "in place", and then rotate the entire figure (use the hip, not the outer group) to put it back where it would have been had it not moved.

tbwoq

I think Carrara has FK and IK. FK(Forward Kinematics) is when you rotate/move the shoulder joint/bone and the rest of the arm/hand moves with it. IK is->(EDIT:) the computer interpets the hand position and moves the other parts in the chain accordingly. I just setup the foot to track the cube(plus orientation) and it works as far as the constraints look OK(at least in my testing with V4.2).

3dOutlaw

So you set it up like the steps I had in the second post, and it worked...or you set it up differently and it worked? Can you describe what you did?

Fenric

Tbwoq: That's just bone rigging, not FK. In Forward Kinematics, the endpoint does not move.

Yes, but I didn't bother with helpers: move the current frame to where it should be, select the foot, drag it to where it should go, then select the hip and rotate it such that the foot is back where you started. You get the same result as you would have if FK existed.

tbwoq

NOTE: I edited my above post to correct the IK information(it was a long day today). :)

Hi 3doutlaw.

I selected the right foot and enabled both tracking and orientation to the cube object. Then move V4(hip, rotate etc.) and the foot would keep as close to tracking as the parenting and constraints would let it. If you go any farther the figure doesn't look right for the posing.

----

Hi Fenric.

The tutorials I watched(Blender/Maya/Softimage?) explains FK as being just a parenting type of movement from the center point(hotpoints). So parenting a single item and moving/rotating the parent will move both items(FK). Correct?

Update:I found the defintions on Forward/Inverse Kinematics that explains it better in the Welcome forum Glossary of Terms.