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A bit lost with constraints

Abelord

Hi. I'm an old artist but I'm new to this world of animation/rigging, so I'm still struggling to grasp the use of some of the concepts like constraints or IKs.

I have done the image setup and the skinning, the bone layout and I was trying to set the proper IKs and constraints to animate a bit more comfortably. I've correctly set up some IKs in the arms, but I'm failing miserably at making the staff stick to the floor as the hand moves, but also look at the hand, so subtle hand movements make the staff rotate subtly without moving from its floor anchor point.

I have made a floor constraint that the root of the staff bone is 100% attached to in translation (so I'll just never move that floor constraint), but when I try to use the hand bone as a second constraint, the staff sort of rotates with it, but much faster than the movement of the hand, therefore never really "snapping" to it. I've tried stuff like "Relative" or changing the Rotate values and such, with no effect.

So I'm a bit clueless at this point, since I don't get the concepts very well in the first place. The ideal setup would be me moving the hand and the staff would adapt to it as the arms adjust accordingly, but I'm not even sure I've done the setup correctly for that. Any insights?

Thanks in advance

skarasuko

So, let me isolate the description of the problems one by one:

The staff is not sticking to the floor as the hand moves.
Subtle hand movements make the staff rotate subtly.
Rotation of the hand bone with its Constraint also rotates the staff, but at a faster rate.

Perhaps the Constraints Hierarchy is incorrect in your Spine project. You can drag the Constraints around and see if you can pinpoint the correct order of priority. Could you also tell us some of bones' parents that are relevant to the problem?

I think I got it. I modified the parenting and Constraints logic. The Staff is not parented to the hand and instead depends on the Transform Constraint to the Hand or to the Ground.

Spine file attached.

Abelord

Oh wow! A million thanks for bothering and taking the time. That was very generous.

In your GIF you seem to have been able to parent it correctly, but in your examples I downloaded, the staff doesn't get to follow the wrist/hand. I've tried with all the controllers, but despite the arm IK works great, the staff remains static and it I move the staff instead, the hand won't follow. Did you do something specific I'm missing?

About your question, there is not much relevant to that case in the rest of the model. The parent hierarchy is the classic

Root > Hips > Spine 1 > 2 > 3 > Arm > Forearm > Hand, with other limbs and secondary elements hanging from their respective parents. In the case of the hand, I've made a few fingers as children. I also made the staff a child of the hand, but I guess I shouldn't.

In any case, that was really useful! I was also struggling with getting IKs with strings of more than 2 bones and this is a great test case, thanks again!

After some further headbashing, I believe my problem comes from the fact that I want to constraint a bone's rotation (Staff) to a bone's Position (Hand). Is that possible?

Erika

Hello, I think this blog post may help you with the hand problem:
Blog: Holding a two-handed weapon

skarasuko

For clarification, the gif and image I posted was based on the first version of the Spine project I attached. The 2nd version should properly represent what you were intending to create.

For Animation: Staff on Hand, I clicked "Match" for the Constraint: Staff on Hand in Setup mode at 0 value and set the Mix of Rotate and Translate to 100 in Animate mode.
For Animation: Staff on Ground, it involves having 5 Constraints being active in Animate mode.

Keep in mind of what constraints are active (not at 0 value). While it is fine to keep a Constraint active in Setup mode if it's a permanent decision, it is good practice to keep some Constraints at 0.

Nate

Thanks skarasuko, you rock! :ohyeah:

Abelord

Thanks, people! It's really getting there, still have to fix a small rotating issue with the hand, but it's been incredibly helpful. Many kudos! 😃