Sample Fortran usage
real*8 positions(3,max_ncharge), radius
integer ncharge
c---------------------------------------------------------
c Set the radius for *all* displayed spheres.
c---------------------------------------------------------
radius = 0.03d0
c---------------------------------------------------------
c Call with ncharge > 0 for normal display. A graphics
c window will be opened interactively the first time
c this routine is called in a program (the outline of
c a small window will appear on the screen; you will have
c to position and size the window).
c---------------------------------------------------------
call sphplot(positions,ncharge,radius)
c---------------------------------------------------------
c Call with ncharge < 0 (presumably at the end of the
c simulation) for "tumbling" display. Depress the escape
c key in the graphics window to return from the routine.
c---------------------------------------------------------
call sphplot(positions,-ncharge,radius)