WORLD
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WORLD
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This is a program that uses mini-X graphics in MINIX to display a map of
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This is a program that uses mini-X graphics in MINIX to display a map of
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the world. The database for this map is supplied, and is an edited version
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the world. The database for this map is supplied, and is an edited version
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of the CIA database. The continents, islands, rivers, lakes, countries,
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of the CIA database. The continents, islands, rivers, lakes, countries,
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and the states of the USA are shown. I have slightly edited the database
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and the states of the USA are shown. I have slightly edited the database
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to fix some arctic islands and remove the Berlin corridor. But some country
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to fix some arctic islands and remove the Berlin corridor. But some country
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boundaries are obsolete, since this map is a few years old at least.
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boundaries are obsolete, since this map is a few years old at least.
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This program only uses integer arithmetic. Floating point is simulated
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This program only uses integer arithmetic. Floating point is simulated
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using fixed point arithmetic. For this reason, the projection used in
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using fixed point arithmetic. For this reason, the projection used in
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the program is rather crude (latitude and longitude are linear and are
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the program is rather crude (latitude and longitude are linear and are
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parallel lines). This means that there is much distortion for the lands
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parallel lines). This means that there is much distortion for the lands
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which are near the North and South poles. If floating point was avaiable,
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which are near the North and South poles. If floating point was avaiable,
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a good projection could be used instead (such as a true spherical view!).
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a good projection could be used instead (such as a true spherical view!).
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The file "world.map" is the database, and should be installed in "/usr/lib".
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The file "world.map" is the database, and should be installed in "/usr/lib".
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Otherwise you need to edit world.c and change MAPFILE as desired.
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Otherwise you need to edit world.c and change MAPFILE as desired.
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To build the program (assuming mini-X is installed), use the command:
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To build the program (assuming mini-X is installed), use the command:
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cc -o world world.c -lgraph
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cc -o world world.c -lgraph
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When the program starts, it draws the whole world. After this is done,
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When the program starts, it draws the whole world. After this is done,
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you can use two of the mouse buttons and the keys to manipulate the view.
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you can use two of the mouse buttons and the keys to manipulate the view.
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To zoom in on a section of the map, move the mouse to the location that
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To zoom in on a section of the map, move the mouse to the location that
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you intend to zoom in on, and press the left mouse button. Then when you
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you intend to zoom in on, and press the left mouse button. Then when you
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drag the mouse, a rectangle (the zoom box) will be drawn to indicate the
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drag the mouse, a rectangle (the zoom box) will be drawn to indicate the
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current area that you are zooming into. Notice that the point that you
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current area that you are zooming into. Notice that the point that you
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start the zoom box on will be the center of the zoom box, NOT one of its
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start the zoom box on will be the center of the zoom box, NOT one of its
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corners.
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corners.
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While keeping the mouse button pressed, you can use the 's' and 'm' keys
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While keeping the mouse button pressed, you can use the 's' and 'm' keys
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to switch between the 'scaling' and the 'moving' modes of the rectangle.
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to switch between the 'scaling' and the 'moving' modes of the rectangle.
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The scaling mode makes the size of the zoom box vary as you move the mouse,
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The scaling mode makes the size of the zoom box vary as you move the mouse,
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but keeps the center of the zoom box fixed. The moving mode keeps the size
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but keeps the center of the zoom box fixed. The moving mode keeps the size
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of the zoom box the same, but moves the box around as you move the mouse.
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of the zoom box the same, but moves the box around as you move the mouse.
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Note that the width and height of the zoom box change together to preserve
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Note that the width and height of the zoom box change together to preserve
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the aspect ratio of the zoom area.
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the aspect ratio of the zoom area.
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If you have started to do a zoom, but change your mind, then you can type
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If you have started to do a zoom, but change your mind, then you can type
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the escape key before letting up on the mouse button, and this will cancel
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the escape key before letting up on the mouse button, and this will cancel
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the zoom operation. If you really want to do a zoom, then simply let up
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the zoom operation. If you really want to do a zoom, then simply let up
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on the mouse button and the selected area will be redrawn to fit the screen.
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on the mouse button and the selected area will be redrawn to fit the screen.
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At this point you can zoom in further if you wish.
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At this point you can zoom in further if you wish.
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You can return to the top level map by typing 't'. Then you can zoom in
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You can return to the top level map by typing 't'. Then you can zoom in
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again on a different area of the map. Alternatively, you can "zoom out"
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again on a different area of the map. Alternatively, you can "zoom out"
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just a little by creating a zoom box larger than the screen size. This can
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just a little by creating a zoom box larger than the screen size. This can
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be done, for example, by starting a zoom near the top of the screen, and then
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be done, for example, by starting a zoom near the top of the screen, and then
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dragging the mouse down to the bottom of the screen. Repeating this process
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dragging the mouse down to the bottom of the screen. Repeating this process
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lets you slowly reduce the magnification.
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lets you slowly reduce the magnification.
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If you press the right mouse button, the display will show the longitude
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If you press the right mouse button, the display will show the longitude
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and latitude of the location on the map covered by the cursor. You can then
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and latitude of the location on the map covered by the cursor. You can then
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drag the mouse around with the button held down, and the coordinates will
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drag the mouse around with the button held down, and the coordinates will
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continuously track the cursor location. Letting up on the mouse button
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continuously track the cursor location. Letting up on the mouse button
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removes the coordinate display.
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removes the coordinate display.
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Typing 'q' will quit from the world program.
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Typing 'q' will quit from the world program.
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Enjoy!
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Enjoy!
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David I. Bell
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David I. Bell
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