View Full Version : Corrective Blendshape problem for open jaw

02 February 2008, 11:01 AM
hello evryone...
I want to use a corrective blendshape so that as I rotate the jaw for my character the corrective blendshape is triggered in such a way that the end result is exactly what i want for opened mouth.
To achieve this, first i opened the jaw to its most extreme pose, duplicated the mesh and moved it to a different position. then i moved the vertices around the mouth area of the duplicated mesh to get the exact shape i want. after that i created the blendshape with default options. then i SDK the blendshape to the jaw rotation such that as the jaw is opened more and more, the more the blendshape comes into effect. it worked fine when the character was in its default position. but when i moved the character to a different position and opened its jaw, the corrective blendshape begins to take effect but the mesh slides back into its original default position.
I used different deformation orders to create blendshapes hoping to solve this problem but that didn't work.
For example when i created the blendshape using front of chain option and move the character to different location, it doesn't slide back to its default location but there is an additive effect in the opening of mouth. i mean the blendshape value gets added to the jaw rotation giving twice as much the effect as desired, thus resulting in the mouth opening too much.
Afterwards i used the lattice deformer to change the duplicated mesh (this time with the jaw closed and in its default position) to the desired shape and created a front of chain blendshape and SDK that to jaw rotation. this worked fine as i imagined but i can't get the ease and decree of control and customization that i can get by moving the individual mesh vertices. no matter how much i tweaked the lattices i couldn't get the shape i want.
so if anyone knows the solution to this problem, please reply....thanks!

02 February 2008, 10:33 PM
Sounds like the Order of Deformation is wrong. You need to RMC on the head goto Inputs->all Inputs. The stack should appear.. to read the stack, you read it from bottom up. So the one on the bottom happens first and the one on top happens last.

If I am correct the BlendShape is happening after the SkinCluster ( remember how its read), MMC the blendShape till its underneath the skinCluster, so it happens before the skinCluster. you may have to move the skinCluster if you can't move the blendShape, that will happen if the blendShape is at the very top.

Hope that was clear,
-Brian (

03 March 2008, 12:43 PM
hey..thanks for the reply!
i changed the deformation order but that didn't solve the problem totally. the mesh sliding was not there but then there was double transformation resulting in the opening of mouth too much. but i guess i've found the solution.
i made the mesh copy in the mouth opened position so thats why it was giving twice the desired effect. so i deleted that blendshape node and created a new one, this time by duplicating the mesh in its default pose. i then moved around the vertices around the lips and mouth area of the morph target while keepin the jaw opened in the base model to get the exact shape i want. i created the blendshape using front of chain. afterwards i SDK it to jaw rotation. and well..this solved the problem for the corrective blendshape for the opened jaw.
but now i have a problem with eyelids closing in. i created 2 morph targets for the eyelids and created the blendshape using in-between mode and front of chain. now the problem is i want to add that single slider (in front of chain mode ) to the existing blendshape folder which is also in front of chain mode. this way i can mix all the controls independently and without double transformation effect. but i couldn't find a way to add a slider (which is created in in-between mode) to the former blendshape folder.
i'm doin this coz i found a problem with parallel mode such that whenever i move and rotate the character to a different location the eyelids behaved weirdly. they stretch and squash out and cut thru the eyeballs while closing in.

03 March 2008, 01:40 PM
Maybe you can try using Pose Space Deformer mel script to do your corrective blendshape

hope it helps

03 March 2008, 09:11 AM
thanks..! thats exactly what i need.:) :thumbsup:

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