Hi!
first, it is good that you moved the blendshape befor the skincluster in the deformer hierarchy, because otherwise the skincluster is overwritten by the blendshape.
Your targets should not move when you move the head, it could be that you used "duplicate special" with the "duplicate input graph" option active to make those duplicates, I couldn't tell because you didn't select any of them in the video. Select a targetmodel, and check if the skincluster is listed in the inputs. if it is, break the connection to it in the Node Editor. This might already solve your problem.
If that doesn't solve the problem, your issue is probably this:
Since you had to pull your blendshape below your skincluster, I'm assuming the skincluster was already active when you created it and deforming your mesh, it could be that your head joint was not in bind position when you duplicated the targets, therefore moving the head up from the blendshapes perspective. This is why it is important to alway put the "envelope" attribute on all active deformers to 0 before introducing a new one.
There are some ways to fix this, but sadly, none of them is really elegant. Atleast the ones I know of...
Method Number 1:
This version is more exact, but for it to work you need a blendshape target that was created at the same time as the others and still is in the default expression. If you don't have an extra duplicate somewhere, you probably can set the "envelope" attribute on the tweak input of one of your targets to 0 and achieve that, depends on how you set up your targets.
1) connect that target to the blendshape
2) duplicate the head that gets transformed.
3) set the target to 1, you now should see your head moving up without deforming.
4) duplicate the head in the upper position
5) create a blendshape from the head in default position to the head in upper position.
6) set target weight on this blenshape to 2, you should now see the upper head moving downwards below the default position.
7) duplicate again and then delete the previous duplicates. You now have a default shape that offsets the translation of the vertices.
😎 connect the new duplicate to the blendshape on the head
9) put the weight on the new traget on 1
10) for all the other targets, put the weight on 1, duplicate the head, put the weight on 0, one after the other.
11) create a new blendshape with the new targets.
Method Number 2:
1) create a distance Tool (Create-> Measure Tools -> Distance Tool)
2) click twice into your Scene to create the Tool
3) Snap both created locators to a vertex on the top of your head that shouldn't move when you trigger the Blendshape.
4) Select the vertex you snapped to and one of the locators
5) Create a point on pointOnPoly constraint. (Rigging Toolset, Constrain -> Point on Poly)
6) Set one of your targets to 1
You now should see one Locator moving along with the head and the distance tool giving you de distance of the unwanted movement. Now you have two ways of proceeding.
1: eyeball it
1_7) select all your targets in vertex mode
1_8) move them downwards until the locators match again and the distanceDimention tool doesn't show a distance.
This might take a bit, and you maybe wont get it 100% correct, but you should atleast try to get the distance to <0.0001, because the offset you'll be left with is cummulative for each target.
2: use a script (this only works if the offset is on 1 single axis)
2_7) select all your targets in object mode and then the distanceDimension tool.
2_8) run the following script from a Python Tab:
import maya.cmds as mc
def moveObjectsComponentspace(dir = 0):
sel = mc.ls(selection = True)
dist = sel[-1]
offset = mc.getAttr('{0}.distance'.format(mc.listRelatives(dist, c = True, s = True)[0]))
sel.pop(-1)
mc.select(cl = True)
for s in sel:
vtx = cmds.ls(sel[0]+'.vtx[*]', fl=True)
mc.select(*vtx, add = True)
if dir == 0:
mc.move(offset, moveX= True, ws = True, r = True)
elif dir == 1:
mc.move(offset, moveY= True, ws = True, r = True)
else:
mc.move(offset, moveZ= True, ws = True, r = True)
moveObjectsComponentspace(dir = 1)
This is a quite common mistake. In the future make sure that all your deformers are set on Envelope 0 whenever you add a new deformer to avoid having to do this again.
I hope this helps!
