I've been trying to make a spring work using blend shapes for quite some time now. my theory is that if i use blend shapes instead of using my method of creating the Geometry then it'll save space and time (i have to make 10 of them one for each joint in the fingers.)
the way I've created the springs is as follows:
-Using a helix as a guide i create a spiral curve
-I move the centre of the curve to the tip of the spiral
-I snap a NURBS circle to the end of it and extrude along to create the geometry .
-i use the same method to create the hooks on either end of the spring.
to make the spring deform correctly I use a distance measure tool and link it to the curves "scale Y" node through a Multiply/Divide Utility to get the desired stretching. I parent the points to the two halves of the joint and it stretches away nicely when I rotate the cylinder in the middle of the hinge. I get it to point in the correct way using an aim constraint to the bottom locator of the distance measure.
The problem comes when I try to make the hooks stay in contact with the main spring. if I connect them to the curve geometry they deform strangely.
if I separate them out and re-attach them when i make the blend shapes all the shapes work fine Except the first and second shapes. the movement just mangles between them.
I taught it was an issue with the two shapes being too far apart in terms of modification but I've made increments of down to 1.5degrees and it still does it.
theyre all created from the same object so they have identical poly counts. and I've made certain that there are no overlaps to interfere with.
anyone have any ideas as to why just this first shape is acting strangely?
I'm using Maya 2008 on windows 7
Here the shapes are un-blended:
Here is what it does when blending between the two: