Confining an unstretchable object
cf 1-D fiber:
¨
curves smoothly
2-D sheet
¨
?
Unstretchability constraint: No Gaussian curvature
must have one straight direction, or
director
at each point
mild confinement
Þ
vertex
2 vertices
Þ
sharp
ridge
canŐt curve
along
or
.
front and back face
must be
flat