I have a general question about shape keys. For example:
Suppose one has modeled a character, and then created some shape keys that affect the lip region - such as a smile and a wicked grin. Then one decides that one would like the character to have thicker lips – for all the shape keys. What I would like to do then is to just to modify the lip thickness of the Basis shape key - and then, as seen in the 3D window, all of the shape keys should (at least optionally) get thicker lips.
In fact, from reading the manuals
(for example http://wiki.blender.org/index.php/Manual/PartVIII/Shape_Keys)
I would have thought that this would happen automatically.
If the shape keys store differences (deltas) relative to the Basis shape key (when the Relative button is pressed in the Shapes panel) - then altering the Basis shape would automatically change the appearance of the other shapes in precisely the manner I want. But for some reason it does not work that way - at least not for me.
If I edit my Basis shape - nothing happens to the 3D apperance of the other shapes.
As far as I have bee able to figure out - there are two ways to partially achieve what I want (without having to manually fix all the shape keys):
There is a possiblity in Blender to edit the Basis shape and then, with the edited vertices selected, one presses W->Propagate to all shapes.
But this just sets the appearance of those particular vertices, for all the shape keys, to be identical to those of the Basis shape key. The relative “deltas” (of the vertices in question) for the shape keys are lost. This method works great if I want to give my character larger ears after I have defined the smile and the wicked grin shape keys. It does not, however, work for giving the character thicker lips while maintaining the general lip shape of the smile and the wicked grin.
One can add a second Basis key “Basis2”, based on the original Basis key. One edits “Basis2” to get thicker lips. Then one cranks up the the Key value slider of Basis2 to 1 - and simsalabim - all of the shapes get thicker lips just like I wanted.
But then , while fine tuning for example the smile shape key, the character still has thin lips. One would have to swap to object mode to see how it really looks,
go back to edit mode and push the vertices etc.
The feature that I want seems like such a useful and (comparatievely) easily implemented feature that I find it hard to believe it is not already a part of Blender.
And in truth, from reading the manuals i get the impression that the behaviour I am after should be the default behaviour. So, am I missing something? Is there a way to make changes of the basis shape propagate in a relative manner to the other shapes?
Thankful for any help.
P.S I am running Blender 2.45 on OSX 10.4.11 on an Intel Macbook.