View Full Version : ffd problem that is leaving me baffled..

01 January 2009, 09:48 PM
Hello all!

I asked this question also over in the max forum, hopefully I can get a response here...

I'm having an issue with FFD on a cartoon rig I'm working on that is baffling me. I'm relatively new to this so if the fix is easy... slap me. ;P

I'm rigging a cartoon mouse using Paul Hormis's technique for biped, since I'll be using mocap on the little guy. The eyes are toony so I decided to use ffd to deform the eyes how I needed. Hyperigger (Hormis's script) creates an eye rig that skins the eyeball to a lookat rotation object. Now, if I use ffd in the stack underneath the skin modifier.. ffd doesn't work the way I understand it should by the posts I've read here. The whole eyeball rotates (so the stretched portions of the eye go through the mesh, instead of rotating like if it was spherical)

If I move ffd up the stack, above the skin... it works while I have the character in fig mode..however, when I take the character out of figure mode , the eyeballs revert back to spherical and I see tha the ffd lattice does not follow the eyeball around like it should.

I've experimented by not applying the hyperrigger script and creating just a standard lookat constraint between the eyeballs and a dummy object, but then ffd doesn't seem to work either, the stretched eyeball rotates fully, going thru the mesh... aaarrghh!

What am I doing wrong here? Am I missing something in the ffd concept? (does the same whether I use ffd 4x4x4 or ffd(box) modifiers.. aren't they the same thing anyway?) I've looked at several tutorials, read the manual, and unless I'm missing something... it should work.

Thanks in advance for all the help!


01 January 2009, 10:18 PM
Hi there. I think there is actually a thread about this one.

I'm not 100% sure if you have separate eyeballs and lids, but i'll assume you have and i'm not either quite sure if this is something specific to hyperigger... i didn't read your post that thoroughly... But if it is just the case of eyeballs not deforming properly:

Use *Spacewarp* FFD Box instead of modifier. It's in Create Panel, Space Warps, Geometric/Deformable, FFD(Box).

Add it to scene then align it to your eyeball so that whole of the eyeball (+lids) is inside volume. Bind mesh(es) to FFD space warp. Now you can deform bound meshes with your FFD lattice.

"Look at" rigs work fine this way so does parenting of lattice and eyeball to head. You could also parent eyeball to lattice, then lattice to head and you can also deform lattice indirecty too, which is nice (bones etc.)

Hope this helps!

01 January 2009, 11:34 PM
aja! Ok... I'll give this a try tonight. But a dumb question then, what is the difference between the modifier ffd and the "spacewarp" ffd box?

thanks for the tip though, I really appreciate it..

and yes, I do have separate eyeballs!



01 January 2009, 11:43 AM
the space warp uses an ffd object and it works in the world space and not in local.
which means if you rotate an eyeball with an ffd mod the ffd will follow the eye.
but with the space warp they are two different objects.
space warp is what you are looking for.

01 January 2009, 12:44 PM
Hi! i ran across this problem some time ago as well. here is how i fixed it.
In the scene i make two sets of eyeballs.
EyeRigMesh (left+right) Handles deform and rotation
EyeRenderMesh (left+right) Handles the positioning.

1.The idea is that the EyeRigMesh collects FFD and ROTATION and drives the EyeRenderMesh through a SKINWRAP-modifier. These eyes stays at the same space in worldspace/maincontroller-parentspace at all time.

2.The EyeRenderMesh holds the skin-Modifier above the skinwrap-modifier. And since both rotation and deformation is applied BEFORE the skinning, it should work nicely.

here is a flowchart of the data:
FFD + RotationControl --> EyeRIGMesh-->\
____________________________________--> EyeRENDERMesh (contains SkinWrap+Skin)
YourRigSystem ------------------------->/

hope this helps :) Its a tricky problem..but quite solvable :)

01 January 2009, 12:14 AM
hmmmm... thanks guys for all the suggestions! I'll keep ya posted and give them a try as soon as possible!

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