Dial Box
Eric Pepke
July 2, 1993

Summary: Description of support for SGI dial box

There is now preliminary support for the Silicon Graphics dial box.  We
don't have any other programs that use the dial box for comparison, so I
pretty much just guessed at useful functions.  If you have any better ideas,
let me know.

The dials now only work when the cursor is in a visualization window and
control aspects of the observer.  Turning a dial changes the value quickly.
If you hold down the Shift key, it works one-tenth as quickly for fine 
adjustments.  All dials have a normal function, and another function which
works when you hold down the Alt key.

The dials are arranged in two columns of four each.  The functions are as
in the following diagram:

+-----------------------------------+-----------------------------------+
|                                   |                                   |
| Normal: Rotate space left/right   | Normal: Move space left/right     |
|                                   |                                   |
| Alt: Rotate space around world    | Alt: Move space +X, -X            |
|      Y axis                       |                                   |
|                                   |                                   |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
| Normal: Rotate space up/down      | Normal: Move space up/down        |
|                                   |                                   |
| Alt: Rotate space around world    | Alt: Move space +Y, -Y            |
|      X axis                       |                                   |
|                                   |                                   |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
| Normal: Rotate space cw/ccw       | Normal: Move space farther/nearer |
|                                   |                                   |
| Alt: Rotate space around world    | Alt: Move space +Z, -Z            |
|      Z axis                       |                                   |
|                                   |                                   |
+-----------------------------------+-----------------------------------+
|                                   |                                   |
| Normal: Move near clipping plane  | Normal: Zoom wide/narrow          |
|                                   |                                   |
| Alt: Move far clipping plane      | Alt: Change binocular spacing     |
|                                   |                                   |
|                                   |                                   |
+-----------------------------------+-----------------------------------+

The move and rotate knobs are set up so that, in the initial default 
observer placement (X to the right, Y to the top, looking down the Z axis)
the normal and alt functions have the same effect.  The alt functions
are in the world coordinates, while the normal functions are in the
observer coordinates.