Child Of Constraint Does Nothing

Hey guys,

I’ve been trying to animate a Mixamo Rig of a soldier for a FPS and I’ve been following these tutorials:

What the guy does is:
  • creates a bone in the soldier’s armature for the gun (named Weapon)
  • Create a bone in the armature for the magazine (named Magazine)
  • Create two vertex groups for the gun and model called Weapon and Magazine, and then add the appropriate vertices to each group
  • Add a armature modifier to the gun model (the vertices are mapped/skinned to the Magazine and Weapon bones)
  • Make the Weapon bone the parent of the Magazine bone using a Child of Constraint.
  • Then he makes the Weapon bone the parent of a hand bone in the soldier armature using a Child of Constraint.

The thing is that when I do that, I can get the magazine to move with the gun if I move the gun using the Weapon bone. However the Child of Constraint does nothing when I make the hand bone the child of the weapon bone using a Child Of Constraint. What is meant to happen is that if I move the Weapon bone the hand bone moves to. Once I’ve got that working I can move the rig so that the soldier is holding the gun and when I move the gun the soldier keeps holding it.

Blend file.

This has been driving me mad. Thanks in advance for anyone willing to give it a look.

You don’t have an IK hand in your armature. “He make the IK hand bone the parent on the weapon bone…” Not an FK hand.

Exactly as stilltrying stated, you will need to create an IK chain for the arm. Without IK there is no way for the arm to follow the weapon. You will then parent the IK bone to the weapon bone. Although it doesn’t make much sense. You should instead parent the weapon bone to the IK hand bone. That way you can move the IK hand and the gun will follow, but you can move the gun independently.

Thanks stilltrying and thedaemon. I thought that you just enable IK and when the gun moves the bone, the arm bones will rotate and move accordingly. I looked up how to create a IK chain and I will try and get it working.
The whole reason for parenting the hand to the gun rather than the gun to the hand is efficiency. If I get the hand correctly parented to the gun, I just need to position the hands perfectly on the gun once and they will stay that way as I move the gun about. Parenting the gun to the hand also makes doing a animation of aiming down the sight incredibly difficult. You need to repeatedly move and rotate the hand bone to get the gun positioning perfect.

Thanks stilltrying and thedaemon, I’ve messed around with the IK chain and managed to get the hands to track the gun. I found that saving the animations was a bit of a pain that way. Anyways thanks, I’ve learnt something new.