World DataBase display routine: Version 2.0

This program is an enhancement on Mike Groshart's routine for displaying
the CIA database of the geography of the world.  The executable file is
under 11K, and its takes about 137K to execute, including hi-res interlace
screen and intuition interface.

Changes:	

	It uses slider gadgets for adjusting the latitude and longitude and 
	   magnification factors.
	It uses integer arithmetic for scaling, hence faster calcs
	It uses area clipping to avoid spending time plotting with 
	   off-map points
	It can compensate for monitor "stretch" which for the 1080 requires
	   a stretch factor of about 1.2, figured at the equator.  I.e.,
	   the perceived shape of (e.g.) Africa, with stretch set at 1.20,
	   is closer to the shape seen when one looks at a 3-D world globe.

NEW:	Once a map is displayed, clicking the LeftMouseButton will readjust 
	   both the Longitude and Latitude (the center point of the next 
	   display) to that of the pointer, based on the current display.
	   Therefore, it should be done BEFORE making any changes in the
	   Magnification factor.


NEW: 	WDB Automatically selects the input file based on the magnification
		factor:
			mag  0.85 -  2.00   --> wdb.5.all     25,890 bytes 
			mag  2.00 -  6.00   --> wdb.4.all     82,080 bytes
			mag  6.00 - 12.00   --> wdb.3.all    156,960 bytes
			mag 12.00 - 36.00   --> wdb.2.all    652,428 bytes
			mag 36.00 -125.00   --> wdb.1.all  1,068,408 bytes


FILES:
		In this arc are included

			the WDB program,
			this readme file,
			wdb.5.all

		In another arc <WDBData.arc> are points files 
	for higher magnification levels:
			wdb.4.all
			wdb.3.all

		The other point files are too large for a BBS to handle 
	efficiently.  Get them from me or Mike Groshart at an AUoH users 
	group meeting.


OPERATION:

	Call it from CLI:   wdb


	The name of the file being shown appears in the lower right of the
Control Window.  If the automatcally selected file is not available in
the current directory, the most accurate file (lower numbered file)
available is used.  This means that called from a floppy disk WDB can
normally access only the 3 smallest files (wdb.5.all to wdb.3.all).
The file wdb.2.all must be called from its own floppy disk; and 
wdb.1.all must be called either from RAM: or from a hard drive.

	Using various files allows for displays of greater magnification 
to maintain a better detail level, without the time penalty of passing
through the largest file for displays that require lesser detail.

	Perhaps someone will have better ideas as to when the different 
files should be called in. Speak up.

	If a special "points" file is specified on the command line, this
will cause WDB to supress the automatic file selection. I.e.,
"WDB wdb.3.all" will display only points from the file wdb.3.all.


Send further suggestions and bugs to be fixed to me.


Bob Dufford
Amiga Users of the Heartland
P.O.Box 1432, DTS
Omaha, NE.  68101-1432

Or on Larry's Hot Tub (402) 571-4316 (Fidonet 1:285/15)