I've just finished writing the macro which will later be used to interpolate
among the different presets for the pose of the mouth.
One might think that writing an interpolation macro from one spline to the
next is rather easy, but its not. Simply interpolating from one set of nodes
and directions to another set can get very cheesy results. My first idea was
to parse the spline and place a set of nodes along the spline, where each
node has the same distance to its respective neighbours, in effect having an
even distribution of nodes along the spline. But just interpolating the
shapes didn't work, as the positions for the mouth's corners changed from
shape to shape.
Finally, I came up with following solution: The mouth is formed with a
spline which has nodes at the corners and the middle section of upper and
lower lip. The nodes' positions are simply interpolated. But the directions
attached to them are handled slightly different for the corners. Instead of
just interpolating, I interpolate the length, but the direction is rotated
around an arbitrary axis. This simulates a crude method of muscles flexing
the corners, and gives quiet pleasant results.

In the animation that follows you'll see the mouth animate through various
poses: Wide-Smile, Sad, Content, Frightened, Wide-Smile (for looping
reasons). They don't have to be one after another, I can even interpolate
during interpolations.

For the final worm, I plan to additionally introduce displacement splines
which will each cover a quarter of the mouth, to make things like
cartoonish-shivering or "waving" of the lips possible. Though I'm not too
sure if it will be used in the short, I want to make sure that the setup
leaves near to no room for improvements (because there's nothing than can be
added once everything is there).

Comments and suggestions welcome.

Tim

-- 
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights
Email: tim.nikias (@) gmx.de



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