VIP is a java applet that calculates the
visibility polygon in linear time.
there might be a problem while loading or saving files. this might
not work with actual browsers because they don't support the standard java 1.0 file
dialogs. try the java appletviewer from sun. the applet needs your permission to read
directory contents, to save or read a file.
- input a polygon
- press left mouse button to set
- when finished press right mouse
button to connect the first and the last point.
- the polygon should be simple.
if it's not simple, you get a message and you have to draw the polygon again.
- set the visibility point
- simply click where you want to set
the visibility point. you can also drag the point and see how the visibility polygon
- the visibility point should be
inside the polygon. if the point is outside, it changes to blue.
- editing the polygon
- you can drag and drop polygon
points. if you drag a point, such that the polygon wont be simple anymore, the mouse
releases the point before that happens.
- if you click on the zoom-button,
you switch to zoom mode. if you want to leave the zoom mode, simply click again on that
- in zoom mode you can draw
rectangles to specify the area you want to zoom in. the aspect ratio will be maintained.
click the right mouse button to see the previous adjustment.
- loading and saving from/to local
- you can load and save scenes to
your local drive simply by clicking on the open/save buttons. however, this does not work
for the most browsers, because their java-implementation does not contain the class
FileDialog. you can use the 'appletviewer' from sun instead.
- in order to load and save work,
the applet requires approval to read directory contents, to read / write files. the method
to give the approval depends on the browser you use.
- loading and saving over the
- this applet can download saved
scenes via the internet using an url connection and the http protocol. clicking on the
network load button will pop up a dialog to select a file for download. this might take a
while depending on your connection.
- uploading works in a similar way.
- replay control
- for every scene you can replay the
calculation of the visibility polygon in detail. (step by step.)
(c) 1997 by Thomas Wolf