// Idea for bounding for catmul-rom spline
// Rune S. Johansen

#declare Number = 8;
#declare Seed = seed(0);

#declare Points = array[Number]
#declare C = 0;
#while (C<Number)
   ##declare Points[C] = <rand(Seed),0,rand(Seed)>*2-1;
   #declare C = C+1;
#end

camera {location 2*y look_at 0}
#default {finish {ambient 1 diffuse 0}}

sphere_sweep {
   cubic_spline Number
   #declare C = 0;
   #while (C<Number)
      Points[C] 0.01
      #declare C = C+1;
   #end
   pigment {color red 1}
}

union {
   #declare C = 1;
   #while (C<Number-2)
      #declare P0 = Points[C  ];
      #declare P3 = Points[C+1];
      #declare P1 = P0+(Points[C+1]-Points[C-1])/6;
      #declare P2 = P3+(Points[C  ]-Points[C+2])/6;
      cylinder {P0, P1, 0.01}
      cylinder {P1, P2, 0.01}
      cylinder {P2, P3, 0.01}
      #declare C = C+1;
   #end
   pigment {color rgb 1}
   translate -0.02*y
}