> restart: with(plots): with(plottools):
> x:=3*cos(Pi*t)+1/(1+10*t^2):
> y:=2*sin(Pi*t)*(1-t^2)^5:
> r:=0.5*(1+sin(Pi*t/2)*sqrt(1-t^2)):
> bal :=tubeplot([x,y,0],t=-1..-0.8,
>       radius=r,numpoints=5,tubepoints=13,
>         scaling=CONSTRAINED,
>         orientation=[-160,70]):
> jobb:=tubeplot([x,y,0],t=-0.8..1,
>       radius=r,numpoints=37,tubepoints=13,
>         scaling=CONSTRAINED,
>         orientation=[-120,60]):
> display(bal,jobb);

> vrml(display(bal,jobb),`kancso.wrl`,
> background_color=COLOR(RGB,0,1,1), shininess=0.3, specular_color=COLOR(RGB,1,1,1)):
> vrml(display(bal,jobb,color=YELLOW,style=PATCH),
> `kancso2.wrl`,background_color=COLOR(RGB,0,0,1), shininess=0.5, specular_color=COLOR(RGB,1,1,1)):
> midpoint := proc(x)
>      local v, n, g, i;
>      v := [op(x),x[1] ];    n := nops( x );
>      g := ( a, b) -> 1/2*( a + b ) :
>      [ seq( g( v[i], v[i+1] ), i=1..n)];
> end:
rbal :=convert( op(1,bal),POLYGONS):
rjobb:=convert( op(1,jobb),POLYGONS):
display({map( midpoint, rbal),
         map( midpoint,rjobb)},scaling=constrained,
   style=patchnogrid);

> vrml(display({map( midpoint, rbal),
>          map( midpoint,rjobb)}),`rkancso.wrl`,
> background_color=COLOR(RGB,0.3,0.3,0.3), shininess=0.5):
> vrml(display({map( midpoint, rbal),
>          map( midpoint,rjobb)},color=YELLOW,style=PATCH),`rkancso2.wrl`,
> shininess=0.5,specular_color=COLOR(RGB,1,1,1),background_color=COLOR(RGB,0,1,1)):
>