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Facial Animation 953
Facial Bone Structure
A common skeletal structure for the face includes:
• Bones to make the upper and lower lips open
and close.
• Bones to push the outer corners of the mouth,
as for a smile.
•Bonestomaketheeyesopenandclose.
• A b one to control the jaw opening and closing.
• The main head bone going straight up from the
necktothetopofthehead.Thisbonecontrols
the head overall, and any vertices not affected
by bones on the eyes, mouth and jaw. Use this
bone to bend the head forward or backward.
Tip: If y ou’ve never set up a facial bone structure
before, refer to a text on character animation for
information on the facial bones needed to create
various expressions.
In gener al, the lower lip bones should be linked to
thejaw,andupperlip,jawandeyebonesshould
be linked to the main head bone.
Facial bone linkage
Ifyouuseobjectsotherthan3dsMaxbones,you
must create dummy objects at the end of each
object used as a bone, and link each one to its
correspondingbonebeforeapplyingPhysique.
This is necessar y because Physique extends lin ks
to the end of the second-to-last object in the
hierarchy, not the last. In other words, if you don’t
create and lin k the dummy objects to the bones,
Physique will not extend links to the ends of the
bones.