Its not possible to use a predefined spline insight a function, like:
#declare Spline=spline{
natural_spline
0,<0,0>
1,<2.5,0>
10,<50,0>
}
#declare Function=function{y*Spline.u(clock*10)}
For example, with splines in a function it would be a great enhancement to
controll the shape of an ISO-object.
