Help for Banchoff Applets
Controlling Windows and Variables
This page looks at issues of interest to a user of configured Banchoff
Applets. Someone wanting to create their own applets will need
more information and should contact the author of this page.
The three sections of help are:
Controlling the view of
The Control Window and the
kinds of controls in that window
recognized by the applet
The applets work best if the screen resolution
is set to at least 1024 by 768.
When you first click the button to open an applet you will see a number
of windows. If possible, arrange then so that you can see them
all at the same time. Each applet will have a single control
window, and one or more 2D-graphical windows and 3D-graphical windows.
view of graphical windows:
2D-graphical windows have menus across the top for Tools, Plot, View,
3D-graphical windows have an additional menu for
We will mainly be concerned with the Tools and View menus.
Some of the applet graphs have hot spots, or point that you can click
on and drag to a new point.
- The Tools menu lets you select the operation performed by a mouse
drag in the graphical window. The options are Rotate (3D
only), Translate, Zoom, and Point.
- In 2D windows, the View menu has a Zoom In and a Zoom out
- For 3D
windows, the View menu options include Default, Up X Axis, Down X Axis,
axis, Down Y Axis, Up Z Axis, and Down Z Axis. The default view
is the "standard" view from textbooks, with the positive z axes going
up, the positive y axis to the right, and the positive x axis coming
out of the plane. If the window is
selected these views can be chosen with keyboard equivalents of space,
x, X, y, Y, z, and Z, respectively.
- For 3D windows, the views of Up X Axis, Down Y Axis, and Up Z
Axis, are worth noting
since they put the effectively project onto the x-y, x-z, and y-z
- If scaling is not otherwise indicated, the drawn axis segments
are of length one.
The Control Window
and Kinds of Controls:
The control panel has six kinds of controls, expressions, variables,
intervals, functions, checkboxes, and readouts, arranged in that order
in the control panel.
The values of the controls can be changed
by the user.
When you change the value of a control by
typing into a box, you need to hit return with the cursor still
the box for the change to register in the applet.
- Expressions can also be thought of as constants. The
applets often use expressions for parameters that the user can
change. If the value of an expression contains commas, the
expression is a vector with a specified number of places.
- Variables have three text boxes and a series
of buttons that look like they belong on
a vcr for forward, back, fast forward, and fast back. The three
text boxes give the minimum and maximum values of the variable
along with the number of step taken in between. The
forward and back buttons move the variable one step up or down.
The "fast forward" and "fast back" buttons animate forward and animate
back until the variable reaches the end of the range, or the button is
pushed a second time. The text box between the buttons allows you
to type in the current value for the variable. If you do this,
hit the return key to register the changed value. If you type in
the current value, it does not have to be within the given range of the
- Intervals have the same three text boxes (min and max value, and
number of steps) as
variables, but without the buttons. They are
used as parameters for graphs. Changing the number of steps will
change the smoothness of the graph.
- Functions have input variables in their names. You may want
to see the page on available
functions to see which functions the applet parser understands.
- Checkboxes allow graphical elements to be hidden to highlight
different aspects of the demonstration.
- Readouts look like a pair of text boxes, but you can only change
the left or input box. This lets you recover numerical
data. The input of a readout can be a vector.
Return to the SLU Banchoff Applets
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Return to the Saint Louis University Department of Mathematics and Computer Science
Last updated by Mike May, S.J. on
May 18, 2007.