How to insert key to a constrained bone with "child of"

Question

I have a character with a sword, sword is inside the same armature of character, and i want to be able to add keys to everything.

An example would be:

• The character moves to the sword is at the ground, so the sword is static and character moves, now the sword does not need keys.

• When character gets the sword, I would like to bind the sword to the hand, ok I can do it with the "Child of" bone constraint and everything seems fine.

• I do more animation keying and everything seems good except if I go the animation begining the sword is not at the ground even if I added keys to be there, because of the "Child of" constraint.

• So then I think: ok, now if I delete the chain of constraint, it would fix the begining of animation because I added sword keys when it was on his hand.

• Delete the constraint but it seems the keys when character had the sword on his hand have not been recorded properly, now the sword stays static.

Is there any way to record a key with the help of a child of constraint and then delete it but keeping the positions of that constraint did?

I cant bake the constraint because is inside the same character's armature.

And I need to be keys, not modifiers or NLA strips, I want to export the animation to Unity.

Answer 1

The "Child Of" constraint is a tricky one to get right. I would recommend using multiple parent objects, and adding a "Child Of" constraint for each parent.

• Create a parent empty on the ground at the "pick up" location.
• Create a parent empty on the ground at the "put down" location.
• Create a parent empty that you parent to the hand bone.
• Create three "Child Of" constraints, one for each parent empty.

Now you can animate the influence of each constraint. When the sword should be at the "pick up" location, that constraint has an influence of 100%. When the sword is picked up, the "hand bone" constraint gets 100% influence. When the sword is put down, the "put down" contstraint gets 100% influence.