Roller_Coaster.exe  is a simple WINDOWS demo program
that generates a B-spline track suported by vertical columns to the x-y-plane.

It takes as input a text file with a sequence of number triplets
that represent the  x y z coordinates  of the spline control points:

 9   9   -5
-9   9   20
-9  -9   -5
 9  -9   12

It assumes that the user wants a closed track, so it loops back to the beginning.

The program needs the two files  glut.dll  and  glut32.dll  in the same directory.

Tu run it, just drag the input file over the  Roller_Coaster.exe  file.
-- Left mouse gives a crystal-ball rotation interface;
-- Right mouse allows to translate the displayed track;
-- Left+Right mouse allows to zoom in and out.

A slider panel allows to adjust the number of supporting "ribs" (columns),
and to change the diameter of the columns and of the track.