--QUAD TREE implementation by David A. Schultz
-- email: elmo@sphinx.cs.nmt.edu

Here is the demo I promised to show that the quadtree works (at least for the
demo!!).  I worked hard to stomp-out bugs, so DO report any apparent bugs
and I'll work on them immediately.  I need a working QT for my work, so if you
find any I'll be sure to fix them!

The makefile might work with no hitches.  If there are any problems I expect
them to be related to finding the X11 libraries and/or the math libraries.
The -I option may be needed.

In foo.sa I generate hemispheres with concentric rings, using the value of the
height of the ring to put in the quad tree.  Unfortunately, the "ring" method
has gaps in the surface of the hemisphere due to aliasing.  For a truly solid
surface just change the loops that generate the surface.  Solid is better,
but also much slower to generate.



The left mouse button gives the coordinates of the mouse in quadtree view
coordinates.

The center mouse button centers the view on the pointer.

The right mouse button gives the coordinates of the mouse in quadtree view
coordinates and the string representation of the element at that point.

'Q' or 'q' pressed in the window quits.
'R' or 'r' resets the view to 0,0 in quadtree coords.  Centered in the window.
'C' or 'c' does what the center mouse button does (for two button mice).
'J' or 'j' prompts you for x,y coordinates to jump to (via stdin).

Resize and re-expose work.  

Note:  There is a 10 pixel border around the drawing of the quadtree to show
	that it is the quadtree that is clipping the drawing and not the
	window!  This was a nifty feature that allows for fast retrieval of
	a given region rather than drawing the whole tree over and over.


If you can use the circle generator and/or special-purpose vector files then
feel free to incorporate them into the library.  Always glad to help.
