[Algorithms] Modifying the min and max altitude in a heightmap

[Sam M. <sa...@dn...>]

This may have a simple solution, but I haven't thought of one yet...

I have a heightmap of altitude values.  The heightmap is subject to
modification during the course of my program.  When I load the heightmap I
compute the maximum and minimum values (altitudes).  During the program, if
a value in heightmap that is modified goes beyond the maximum altitude, I
assign that value to the maximum altitude (and similarly for the minimum
altitude).

However, I also want to be able to tell if the maximum value has _shrunk_
(or if this minimum value has increased).  So far I can't think of a simple
way to do this other than rescanning the whole heightmap whenever a value is
modified, and clearly this is not a practical solution.

Hopefully there's a nice simple method that I'm blind to, so please
enlighten me if you can.  (-:

-Sam
______________________
Sam McGrath
sa...@dn...
http://www.dnai.com/~sammy
ICQ 5151160