Re: RFC: a generic pointer proposal

Doug Ridgway (
Thu, 14 Nov 1996 21:51:56 -0800 (PST)

About the number of dimensions...

I don't know whether things like the SGI bank of knobs should be included
under this, but they have at least a dozen knobs. I can't remember exactly
how many. The ones I saw were 3x4 or 4x4, but I think they are available
larger. (The SGI bank of knobs is a panel with an array of knobs on it.
It's used by various graphics programs for rotating matrices or adjusting
things in 3d models. I can certainly see how I'd want thirty or forty
physical knobs to tweak if I was trying to do the modelling for ``Toy
Story''. A complex Toy Story model had something like three hundred
adjustable parameters.)

Along the same lines, one might imagine Linux running a more specialized
system, such as a chemical plant process control console, a professional
audio mixing console with many inputs or a realistic flight simulator. How
many knobs does a 747 cockpit have?

Then there are also the various VR input devices. A boom-mounted helmet, for
example, is going to need at least six dimensions (three space plus three
rotation) and it's unlikely to be the only thing hooked up. I tried a
setup at the San Diego Supercomputer Center with a boom helmet and a
wheelchair motion input device. Two more dimensions, one for each wheel.
Now imagine a glove. You'd need dozens of dimensions just for an accurate
hand position.

Of course, maybe you don't want to access a VR body suit through the
same interface as your mouse.