10jan02
Experiments with the illiSkel. 

Conventions: Real-time interactive computer animation = RTICA. 
"(Z)" means the so-labelled key on the keyboard. A capital Z
requires the shift-key too.

1. Mouse and keyboard 

The displacement of the mouse-cursor from the bullseye rotates the 
torus about its own center in the turning mode (purple writing), and
about the viewer in the flymode (yellow writing). 

The spacebar toggles the navigation modes. Left and right mouse buttons 
turn about the third axis. The middle mouse button flies/moves forward. 
Hold the shift-key down to reverse (some) actions. 

For PCs without middle mouse button, use the arrow key.

Don't (ESC)ape until you want to quit.

(V) toggles binocular viewing mode(s). 

To view in stereo reshape the window to be wider than high. Cross your
eyes (moving the two apparent bullseyes out of the way) until the torus
fuses into a single image, dead-center. You may wish to adjust the 
eye-separation distance with the (N)ose key. If the graffiti bother you,
turn it off with the (W)riting cycler. 

Hold shift-N to decreasing eye separation through zero to negative,
and watch the torus move behind the stars. 

(Z)ap all parameter changes back to the default values.

The (H)omotopy animates the torus, and (G)aps indicate how the torus
is constructed. You should fly into and then through the torus to 
learn the yellow navigation mode. Both the linear [S]peed and 
the angular speed (called tor[Q]) are adjustable to compensate for
the speed of your computer. Once you found comfortable numbers, 
say speed=0.5 and torq=0.05 (on a really slow computer), you can just
enter this by typing 0.5s and 0.05q. 

The f(O)cal factor changes the focal-distance of your "camera". But
it also affects the near-clipping plane. Play with my s(I)ze and 
the far cli(P)per to learn about the clipping planes.

Experiment also with the (A)mbient and specular powe(R) keys to 
alter the lighting/shading of the surface under a single, infinitely
far, white light source. 

EXERCISE. What can you conclude about the navigator, viewer, animator,
toroidal geometry, optics, and lighting of the illiSkel from just
playing with the RTICA. 

EXERCISE. Devise new experiments, in particular ones which require 
modification of the code to be performed. Make a wishlist of modifications
of the illiSkel.

2. Experiments with the code. [Much more later]

There are "hidden" keypresses embedded to illustrate tools for 
experimenting. For example, the (F1) and (F2) keys manage one toroidal
angle. Observe the rendering errors that happen when the torus surface
overlaps itself. What do the (=) and (-) keys toggle?

To see how these work, use your editor to examine the code. 






