First, “Prorerties” in blenderspeak are a GameEngine doodat, but I think I know what you mean. Second, you can leave out the Lattice (you don’t have to) and use a Shape on the verts of the neck directly.
If the NeckBone runs parallel to the spine (as it should) then you select the Rot-Y IPO in Pose Context in the IPO Window and add a Driver to that. Fill in the name of the Armature, then the name of the Bone (Ctrl.Head) and select the Rot-Axis that Ctrl.Head will rotate to drive the neck bone.
Then you select the Shape IPO in Shape Context in the IPO Window and put a Driver on that with the name of the neck bone and the Rot-Y axis (same procedure as above).
I tried it, but it did not work… If I try to add a driver to the neck-bone, and type in the name of the armature, it says I can’t use the same armature as driver for the neck-bone, and the Ctrl.Head bone, is from the same armature ofcourse…
Thanx for the idea ofcours, Fligh… If it works for you it should work for me too.
The driver is applied to the mesh (which is where the shape key is set … you can’t set a shape key on a bone/armature), with the driver Ob:(ject) being the Armature/bone. I.E. select your mesh, change the IPO curve types to Shape, select the particular shape key from the list on the right of the IPO window, press N to bring up the properties … etc.
A second armature is only needed when using an IPO driver, as an IPO driver object cannot drive itself (the Armature being the object, all bones are still part of that object).
Apparently if you use PyDrivers (a Python driver) this limitation does not exist …according to the release notes anyway. How you’d code the expression / Python code is another thing … Probably be faster to just create that second armature
“For now pydrivers can reference their own object, something normal
ipodrivers can’t. This seems to work fine and is quite useful, but if
tests prove the restriction is necessary, we just need to uncomment a
piece of code in EXPP_interface.c, marked with “XXX”.”