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I am rigging a Pixar lamp as shown in the screenshot above. The lamp bone is tracking 'bulbtarget' and the neck bone is copying the rotation of 'rotateneck'. I want the rotation of lamp bone to be around the joint between rod and lamp like this:

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I added an empty object at that joint and changed the pivot point of lamp, but this isn't working well. How can I make both parts move together without any gap?

If I connect the bones without all the fuss then the problem goes away, but the lamp object won't point towards the target, it will move at some offset angle.

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  This big lamp bone won't do much good there because it's root is in a place where the lamp doesn't have any joints.

  I would solve that with two Locked Track constraints. The first one is for looking up and down. Parented to that is the second bone with another Locked Track to handle looking from left to right. Both are tracking the same target.

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Here's the setup from Haunt's trick bag:

  • Bone 1 is the boss. It has a Locked Track with Z locked and -x tracking bone 3. It can only move up and down. The blue joint is parented to that.

  • Bone 2 is parented to bone 1. It has a Locked Track with X locked and Y pointing to 3. It can only move left and right. The red part of the lamp is parented to that bone. It doesn't matter at all how high bone 2 sits as long as it sits on the axis of the neck. It only rotates around the neck axis anyway.

  • Bone 3 is the target. One and two point there.

  • Bone 4 is there for convenience purposes. The root of bone 1 can't be in the middle of the lamp's head (bone 2 could be, but who cares, you'll hide them anyway), so there's an offset. Bone 4 has a Copy Location Constraint to bone 3 and a Copy Rotation Constraint to bone 1, so the tip of bone 4 is where the lamp is looking. You can make bone 4 unselectable in the outliner. That way you can't miss the target bone.

  In the end, you'll only have two bones visible, possibly with customs shapes: bone 4, so you see the exact focus of your lamp and bone 3, so you can animate the head. Btw, Luxo's neck seems to be perpendicular to his head which makes things a little easier regarding his focus.

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  • $\begingroup$ Thanks for your time,but it seems like whole mesh rotates about the base of bones 1 (2) ...the assembly is like that of neck and head rig of a human. lamp and rod has to rotate separately. Head has to point at something and track it , and neck should be able to rotate. $\endgroup$ – vangap Sep 19 '13 at 4:41
  • $\begingroup$ I added a gif showing the functionality. Please describe what you mean since my rig is physically correct and as far as I know equals the Luxo functionality. $\endgroup$ – Haunt_House Sep 19 '13 at 5:30
  • $\begingroup$ Luxo functionality is that....but What I want is for it to work like human head rig. I want red part(Head)and below rod (Neck) to move separately. $\endgroup$ – vangap Sep 20 '13 at 12:08
  • $\begingroup$ Then you need to show that in your modelling. If you don't model a ball joint or something similar, your neck CAN only rotate like mine does or it will look unconvincing. Our two lamps are similar, only I put the up/down joint at the bottom where the neck connects with the rest of the lamp. If you want the pivot where neck and Lamp meet, just build it with the roots of bone one and two where you want the joint to be. That's the most fundamental advice. Put the roots where the pivot points of your joints are. $\endgroup$ – Haunt_House Sep 21 '13 at 0:47

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