Let us face this scenario: my character will take a step forward, then around and go back to the original position. I usually don’t animate my main control for animations like this, I find it unnecessary and generally difficult.
Problem 1:
The pole vectors is only parented under the main control. If I don’t rotate and move the main control the pole vectors will stay in the same place. Which results in very interesting knee twists when you have turned around.
Problem 2:
The pole vectors are point constrained to the hip joints or the pelvis joint. Now the knees always will turn around with the body, but that that could also be a massive problem.
I totally understand why these things happen, that is not the problem, but what should I do? Just animate the main control or can I do anything else?
I don’t see that it is a big problem, you can reparent your pole vectors but you said they are point constrained to the hips joints so I don’t understand why they would stay with the main control, if you have a hips control to move the character the PV should move with the hips?
You have a rotation problem but that could be fixed by reparenting or using an orient constraint to allow for the pole vec. ctrl to also follow the hip joint orient in Y/ twist.
You could animate it with your main control but maybe you don’t have a world space switch on your feet controls to allow them to not be moved by the main control? ( I have to guess that the “main” ctrl in this case is a world character mover ctrl.
If you expect to have a lot of changes in the orientation of the knee, you could try to constrain or parent the pole vectors to the controls for the feet (that is, to the world-space boxes or locators that control the foot IK).
This makes the knees follow the orientation of the foot, which is usually close to what you want anyway. You can offset the relationship with the twist control on the ik leg. Be sure to push the pole vectors well ahead of the body (and also up , maybe knee height) to keep them from nearing the unstable area along the line of the solver.
This works well for most standing or walking poses. It’s not as good for things like crawling on hands and knees or moves where the the feet get above the head, such as tumbles. Idles where the foot actually rotates out of the axis of the hip-knee-ankle line are also not great this way. But it’s good for the common standing case.
I use an approach which involves aim constraints to automate the knee. It’s essentially an upgraded version of the parented polevector but with less limitation. This works well with crawling and other crazy motions. I saved as ASCII for compatibility, the leg rig is ultra simple just to show the basics of the knee setup. It is easily extendable to include other behaviors you might want, like making the knee looking at a world direction instead of toe direction and stuff like that, even a hybrid with the no-flip knee you’re currently using is plausible.
Download, give it a shot and tell me what you think.
Hi,
I am so sorry for the late answer, I’ve moved to another town and started my internship…
Thank you so much for your answers. The world space switch for the feet sounds pretty awesome, I will look in to it as soon as I can. Or well, I will look in to everything as soon as possible!