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VPHelp.txt
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Viewport is copyright Tomas J. Nally, August 2003.

It is released as Open Source software.

Email the author at Steelweaver52@aol.com


What It Does
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Viewport is a Liberty BASIC program written to illustrate a method for mapping real world coordinates to screen coordinates.  Viewport accompanies an article by Tomas J. Nally written for issue 112 of the Liberty BASIC Newsletter.  That article explains the mapping process more fully.  To read that article, visit the Liberty BASIC Newsletter archives at http://libertybasicuniversity.com/lbnews/.


What You See
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The GraphicBox on the left represents the "Real World".  Let's call it the "Real World Box".  The objects shown in the Real World Box have no significance other than their use in this demonstration.  Think of them as grafitti written on a wall.

The GraphicBox on the right contains the program's representation of the real world objects shown on the left.  Let's call the Graphicbox on the right the "Plot Box".  As the user moves the Viewport within the Real World Box, those objects in the Viewport will appear in the Plot Box on the right.

If the user moves the mouse to the Plot Box, the mouse's screen coordinates and its real world coordinates will appear in the text boxes below the Plot Box.

Moving The Viewport
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To move the Viewport, left-click once in the Viewport's "handle".  The Viewport's handle is the solid black rectangular box in the upper left-hand corner of the Viewport.  When you left-click, do not hold down the left button.  Just click and release.  This attaches the Viewport to the mouse pointer.  When you move the mouse pointer, the Viewport will stay with the mouse and glide around the real world.

Releasing The Viewport
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To Release the Viewport, right-click the Mouse one time.



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