From: Jon M. Taylor <taylorj@ecs.csus.edu>
  To  : ggi-develop@eskimo.com
  Date: Wed, 19 Aug 1998 22:04:32 -0700 (PDT)

Re: LibGGI3D RFC

On Thu, 20 Aug 1998, Olivier Galibert wrote:

> On Wed, Aug 19, 1998 at 05:49:51PM -0700, Jon M. Taylor wrote:
> > > Another  use of 3D  cards here (french CS research  center)  is to use
> > > them  to  compute  the  visibility factors in   a scene  for radiosity
> > > computing by having  the  hardware render   the scene without   lights
> > > effects,  encoding each patch with  a unique color,  and then transfer
> > > back the picture and count the pixels.  I guess it will be possible to
> > > do that with libggi3d for  the rendering and  libggi2d to get back the
> > > result?
> > 
> > 	Sure.  Write a modified radiosity-without-lights shader (probably
> > it would do everything in greyscale) and then draw each patch through the
> > shader and then through another shader which applied a color filter to the
> > greyscale patch before redering it to the final display target.  Is that
> > what you were looking for?
> 
> Nope.  You have   to get the  picture  back in  memory outside of  ggi
> (OpenGL in their case, but anyway) and  count colors there (the number
> of pixels of a given color is directly  proportionnal to the amount of
> energy exchanged between the two patches).  You then use these results
> in an equation system solver.

	Ah, I see.  That would be even easier.  Just color the patches 
however you want and then render to a 2D buffer for analysis.

Jon 

---
'Cloning and the reprogramming of DNA is the first serious step in 
becoming one with God.'
	- Scientist G. Richard Seed