> > My problem is this: In my GUI I have a topographical map which is
> > created by reading data from a 10 meg USGS elevation file, and
> > simply painting the appropriate pixel color on the screen. ...
>
> How about using Xor drawing mode - draw the a/c twice to make it disappear.
The problem there, unless I'm missing something (I haven't used XOR
drawing for much other than rubber banding) is that you're pretty much
at the mercy of the contents of the Colormap for what your object will
look like. The results will generally not be visually pleasing.
It occurs to me that one might be able to do something moderately
clever using the Shape Extension but it would take a bit of research
and experimentation to come up with exactly what.
spl
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