Spheres of Influence Applet Instructions

Contents The Basics Applet Layout Adding Points Selecting Points Removing Points The Graphs Advanced Features Running Demos Changing View Command Parser The Application

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The Basics

Applet Layout

In general the applet is organized as follows:

At the top of the applet is an area with buttons on the left hand side. Pressing one of these buttons gets you a control panel on the right hand side, from which commands are available.
Below this control area is the graph window. Click in this area to add or select points.

Adding Points

Just click in the white graph area of the applet to add points.
If you find no points are being added, go to the Points control panel, by clicking the 'points' button in the control area. Make sure the 'Add Points' check-box is checked. Click it again to make sure. You should now be able to add points.
To quickly add a number of points, click on the 'Add Random:' button to add some random points. The number of random points to add can be entered in the field to the right.

Selecting Points

Go to the Points control panel, by clicking the 'points' button in the control area. Click the check-box labled 'Select Points'. When you move the mouse back into the applet window, you should notice that the point closest to the mouse is highlighted.
If you press the mouse button now, the highlighted point will be selected, which is indicated by a change in the point's colour. If you press the mouse button again, the point will be deselected. To select and deselect multiple points, hold down the shift key when clicking near the points.

Removing Points

To remove all the points in the graph window, go to the Points control panel, and click the button labled 'Delete All'.
To remove only some of the points in the graph, select them as described in the section above, and then click the 'Delete' button in the Points control panel. The selected points will be deleted.

The Graphs

To get the applet to plot graphs, click in the 'graphs' button to show the Graphs control panel. There are a number of checkable options available from this panel.

• Nearest Neighbour
  Checking this option will make the applet display the graph where there is an edge from each point to its closest neighbour.
• Live Add
  If this is switched on, the applet will draw a circle around the cursor with radius equal to the distance between the cursor and the point closest to it. This circle is only drawn if the 'Add Points' check-box (in the Points control panel) is also checked .
• Draw Circles
  This option will cause the applet to display circles around all the points in the graph, with each circle having a radius equal to the distance between its point and the point's closest neighbour.

Advanced Features

Running Demos

The applet is capable of running demo files. To run a demo file, go to the Commands control panel. Type the demo file's name in the field next to the 'Play Demo File:' button, then click the button. The demo files are listed on the web-page with the applet.

Changing View

To change view, you must use a command. To issue a command, go to the Commands control panel, and click in the one line text field at the bottom left of the control panel. This text-field is the command line.

To change the zoom level, type zoom x on the command line, replacing x by a number. The smaller the number, the smaller everything will get, or the more you 'zoom out'. The default zoom value is 100. Examples:
zoom 200 #makes everything spaced out twice as distantly
zoom 50 #makes everything twice as close together
zoom #restores default zoom value of 100

Changing the origin can be accomplished by using the translate command. Type translate x,y into the command-line to change the origin of the view to be the point x,y. Note that this does not affect the coordinates of the points you add, merely the location you're looking at in the graph. The default origin is 0,0.

Command Parser

The applet has a built-in command line, on which you can issue text commands to the applet. To change the view-mode, for example, use the zoom and translate commands. In general, any button or check-box you click in the interface corresponds to a command you can issue.
To learn what commands do what, try clicking the buttons and then examining the command display, above the command line in the Commands control panel. A probably complete list, with terse descriptions of each command, is given below.

• add pt <dbl>,<dbl>
  adds the point specified by the euclidean coordinates to pointset
• delete all
  clears all points
• add random <int>
  adds <int> points randomly to the set of points
• sel pt <dbl>,<dbl>
  selects the point closest to specified point, clearing other selections
• delete sel
  clears the selected points...
• sel add <dbl>,<dbl>
  adds/removes point closest to specified point from current selection
• sel clear
  clears the selection...
• graph <+-> <str>
  if +, will draw the graph denoted by <str>, if - will not draw the graph
• run <str>
runs the demo file given by <str>
• record <str>
  starts recording into file specified in <str> (Not available in applet)
• stop record
  stops recording
• set <str> <bool>
  insert a state with name <str> and value <bool>
• check <str>
  return value of state with name <str>
• update
  this command causes the canvas to update its buffer and draw it to the screen!
• zoom <dbl>
  sets the zoom-value
• zoom
  restores default zoom value
• translate <dbl>,<dbl>
  sets viewing origin to point specified
• control showpage <str>
  the control panel corresponding to <str> is displayed
  

The following states could be set and checked using the set <str> <bool> and check <str> commands:

• AUTOUPDATE
  if true, will automatically update the screen...
• SHOWINDEX
  if true, will print the name of the points next to the point...
• SELECTMODE
  if true, clicking selects points and the closest point to the cursor is highlighted. If false, clicking adds points.
• LIVEADD
  if true, a circle will be drawn around the cursor when SELECTMODE is false

All the above commands can also be typed into a text file, that can then be played as a demo file. Similarily, recorded demo files can be edited in any text editor. In demo files the comment character is '# '.

The Application

This applet is also available as a java application, for you to run on your home-computer. The application allows you to save demo-files, as well as play them back. To save demo-files go to the Commands control panel, type the file name into the text-box next to the 'Log to File:' check-box, then click the check-box. All commands you issue, by typing into the command line or using the interface will be written into the file. To stop recording, un-check the 'Log to File:' check-box.

To Download the Application for Macintosh, click here: spheresapp.sit.hqx
This requires MRJ 2.0 or better.

To download the java archive for Win95, click here: spheresapp.zip

To download the java archive for Unix, click here: spheresapp.tar.gz

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