
 CONTOURS

   This program generates a contour map (lines of equal "height") of a
 3D surface specified as a mathematical function Z=F(X,Y).

   There are nine such functions provided as examples - see the textfile
 'Functions' inside the !Contours directory.

   The user may wish to use his own functions here instead (but don't
 change the first one, which is a random 'terrain' and uses a coarser
 resolution to the others).
 Note that the program assumes that the range of X is (-15,15), the range
 of Y is (-12,12) and the range of Z is (-15,15), so you should use some
 scaling factors as necessary.

 The functions can be chosen by pressing one of the number keys 1,...,9.

 The other keys that can be used are :-
       C - to double the number of contour lines
       R - to double the resolution (probably the most useful)
     TAB - to double both contour lines and resolution simultaneously.

 The default settings are a compromise between detail and speed.

 The display colours can be interpreted as follows:-
         White - highground/snow
         Green - lowland
         Blue  - sea
         Red   - deep water/"hell"
 The green/blue interface is "sea-level" i.e the Z=0 plane.

Copyright:  R.A.Swetman
