Last edited 13apr03 by Wendy Hubbard
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User's Guide


Combo is a graphics program based upon the illiSkel that uses control points and splined curves to represent three-dimensional objects. Curves are built using the iLevelEditor and viewed in the illiLevel Viewer. The 3-D view is controlled through Mouse and Keyboard commands, which allow the user to chose between Flying Mode, Control Mode and Binocular Mode. Click to see a summary of keyboard commands.



For now, our provisional versions of illiCombo work only in Windows98, WindowsNT, and Linux. Present documention is maintained only for the first named platform, and for the commandline invocation of combo.

Change to the directory where the file combo.exe is located. The commandline syntax is:

combo [-i infile.sps [-o outfile.sps]]

You may specify the file you wish combo to read from, the "infile", and you may specifiy the file you wish combo to write to, the "outfile". Both are optional, in which case combo reads foo.sps and write bar.sps by default. The suffix .sps is traditional. This line duplicates the default:

combo -i foo.sps -o bar.sps

When combo executes, two windows appear--the viewer, illiLevel, and the editor, iLevelEditor--with the illiLevel window active. You may resize the windows by dragging the edges, or maximize and minimize using the buttons in the upper right hand corner as with any Windows application. Resizing may freeze your CPU/graphics card, so enlarge with caution.

illiLevel automatically detects the displacement of the mouse from the origin (located in the small circle in the center of the window) which is interpreted as a rotation. Conforming to illiNavigation, in the (default) TURNMODE (magenta) the center of rotation is in near the surface. In the FLYMODE (yellow), the center of rotation is closer to your head. The (SPACEBAR) toggles these modes. To disable all roation (F)reeze the image, by toggling the F-key. (We follow the illiView convention, used also in (W)riting on the screen, that "(K)ey" means that the K-key affects the "key" action in an observable manner.

Press (Z)ap to return RTICA to its default condition. (This feature needs work, for now.)

Press the (F1) key to save the current image.

Press the (Esc) key to exit the program.

illiLevel Viewer


You need a (three button) mouse and a keyboard to successfully navigate in the illiLevel viewer.


To view the image from another angle, move the mouse until the image is oriented the way you want it. (Note: since the image is orbiting around the origin, one side of the object will always be closer to you than the other side.)

You can zoom in by pressing the middle mouse button and zoom out by holding down the Shift key and pressing the middle mouse button at the same time (if you have a three button mouse--otherwise you must use the keyboard to zoom).

You can also rotate the image about the origin by pressing the left or right mouse buttons.


Once you have stabilized the image by moving the mouse to the origin, you may use these keys to move the image in the window:

The left and right arrow keys can be used to move the image left and right.

The up and down arrow keys zoom in or out, respectively.

(Page Up) and (Page Down) keys move the image up and down.

Note: You do not have to hold down the keys to continue the action--just press it once and then press the End key to stop the motion.

Flying Mode vs. Control Mode

in the (default) TURNMODE (magenta) the center of rotation is in near the surface. In the FLYMODE (yellow), the center of rotation is closer to your head. The (SPACEBAR) toggles these modes.

Binocular Mode

(V) Toggles between normal and binocular mode

(N)ose Adjusts the space between the two images in binocular mode

Summary of keyboard commands

On the screen, you will see a menu of options that you can control. Each of these keys will automatically increment or decrement when pressed, and will continue if the key is held down. You may also enter a numerical value from the keyboard and then the key for the variable you want to change.

Holding the Shift button down while pressing many of these keys reverses the action:


Exit the program


Toggles binocular mode


Toggles between CONTROL and FLYING modes




Toggles the screen menu on and off


Change the distance between the images in binocular mode


Change the zoom speed


Change the rotational speed

f(O)cal factor

Change the focal length

my s(I)ze

Change your size in relation to the world

far cli(P)er

Move the far clipping plane


Return image to its default orientation


Slice the image


Change the ambient lighting on the object


Used for 3D picking


Recenters image


Compress or expand the image


Change the plaid design


Freezes current image


Toggles 3D picking mode

iLevel Editor

With the iLevelEditor, you can see a cross section of the object, one level at a time. You can move points in the editor window and see the results simultaneously in the viewer window.

-Use the up and down arrow keys to change the level you are viewing.

-Use the left mouse button to drag a point to a new position.

-You may also flip the curve about its x- and z- axes by pressing the x and z keys.

To download the files required to run the programs, click on the links below:
iLevel Editor

To view the source code, click the links below:
Combo Source Code
iLevel Editor Source Code