G3dX and cglv description

G3dX and cglv are two programs for viewing s3d files.  They do have
some differences.  This document provides a brief description of part
of the functionality of both programs.

Both programs read an s3d file on stdin (G3dX can also take the file
name as a command line argument).  

The mouse button is for moving an object.  For G3dX, you'll want to
type 'g' when you start the program to turn on the virtual sphere
mode.  Then:
	Left Mouse	- Virtual Sphere
	Middle Mouse	- Translate parallel to screen
	Right Mouse	- Move towards/away from screen
Note: in G3dX, the mouse should be positioned in the right quarter of
the screen in order to get the translate in z to work properly.  If the
mouse is positioned elsewhere, then a different operation is performed.

The virtual sphere is a rotation interface.  Essentially, there is a
circle on the screen that represents a sphere.  If you click and drag
a point on the circle, then it rotates the object as if you were rotating
the clicked point on the sphere in that direction.  If you click a point
outside the sphere, then a rotation is done about the viewing axis.

Note that you must press the 'g' key in G3dX to get the virtual sphere.
A dashed-circle appears, representing the sphere.  In cglv, the virtual
sphere interface is the default (and in fact, the only rotational interface).
However, cglv does NOT draw a circle.  The circle used is the maximum
circle that fits on the screen.

Also note: if you want to use cglv to look at shaded images, you should
specify a material property for the surface, and you need to sample normals
in addition to positions.

The keys provided different functionality for the two programs.  Both,
however, give a brief (and not very helpful) list of commands if you
type '?'.

G3dX keys:
	b 	- toggle backface culling
	g	- toggle virtual sphere
	j	- jump to a view of your object
	>	- save the view of your object to the file stateg3d
	<	- read the view of your object from the file stateg3d
	h or Dh	- toggle hidden line removal
	DP	- output what you see as a PostScript file
	^C	- quit

cglv keys:
	b	- toggle backface culling
	f	- toggle frontface culling
	o	- toggle outline of polygons
	</>	- read/write a view (note: format different than G3dX)
	<esc>	- quit