Align to surface

[Pancho]

One last thing for today and then I shut up. Thanks anyway for all the help I got today. Saved my behind.

As in Poobys face deformation tutorial I use nulls on a mesh to do the same thing. Deform a face.
There is a folder with as many nulls as my deformer mesh got vertices. An ICE tree places each Null at a vertex. So far so good. I even can align the rotation with the point normal. But here the trouble starts. So far I use direction to rotation and initially used the y axis as the second vector. In many areas that's o.k. but in others it causes "flipping" or at least uncontrolled rotation. The general alignment to the mesh is fine, but the way the Null rotates around its own y axis is ugly and messes the deformation of the face up.

How do I "constrain" the null to the surface, that each neighbour of the Null "pulls" the null like springs? The null would then not rotate strangely, but rather rotate slightly if a neighbour changes its position. I wouldn't know how to set something up which does this. The null's y axis would still be aligned with the point normal but the other points (the neighbours) would hold the "corners" of the null (eg if you have a box for the display of the null). Some the vectors to the neighbours could help and caclulate some kind of average something. But I'm not sure.

Anybody a guess?