View Full Version : ik handle advanced twist controls not working?

02 February 2008, 07:42 PM

there is something bothering me: may it be that the advanced twist controls (object rotation up, start/end) for the ik handle tool are not working properly in maya 2008?

i tried several settings in a wiped clean new scene but it ikSC solver on the ik handle doesn't evaluate as expected.

thanks for shedding light on this,

02 February 2008, 12:57 AM
Have you tried rotating the nodes you are using for WorldUpObject and WorldUpObject2 in all three axises? If the UpVector is not setup correctly you will get unexpected results. As in not tapering up and down the chain.

If you tried all this.. can you write up what you did so we can reproduce the same error.


02 February 2008, 03:07 PM
hi meljunky,


i rotated every axis for the world rotation up (start and end nodes) also tried every combination of up vector and local axis orientation for the joints.

what i did:

front view -> joint tool -> hold x for grid snap -> place five bones in a chain with each 1 grid space length -> select all bones -> rotate z by 1 degree (so there is a slight bend for the ik handle to calculate on -> freeze transform on all bones to zero the rotation again -> ik handle tool (solver enable, snap enable, all other values at 1, tried both solvers: ikSC and ikRP) strg click on the first bone in the outliner -> strg click on the last bone in the outliner. ik handle pops up. select it. ik solver attributes -> advanced twist controls -> enable -> object rotation up (start/end) -> duplicate the first bone of the chain and the last one -> rename them -> enter their names for world object up and world object up 2.

i would not mind wrong rotation links, fixing the up vectors is easy, but for me the rotate start/end controls didn't work at all, no matter what i tried.
as mentioned the question is rather if rotation up (start/end) works for ik handle at all.

thanks for reading, again,

02 February 2008, 07:24 PM
...tried both solvers: ikSC and ikRP

Did you try the "IK Spline Handle Tool"?

-Brian (

02 February 2008, 08:07 PM
hi meljunky,

the thing was that i didn't want the stretchy spline, just the twist and a fixed distance control, i ended up scripting it. if you stitch two "twisty" ik splines you get an issue
in the mid point between them because the controls of the ik spline twist bend the spline outwards when bent, so one has to orient them along a bone, otherwise they will break the angular top structure. for better understanding, i stitched the ik splines to an upper and lower arm bone, so the elbow bent gave them problem.

thanks for answering,

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