> On Tue, 06 Nov 2001 08:41:43 -0500, "Greg M. Johnson"
> <"gregj56590[:-0]"@aol.com> wrote:
>
> > The following scene file gives a black screen.  IMHO it should give a
> > green screen.
>
> The behaviour is probably undefined becouse of fog formula from 6.9.3 chapter.

This bug-carry-over-from 3.1g could be fixed by changing:

PIXEL_COLOR = exp(-d/D) * OBJECT_COLOR + (1-exp(-d/D)) * FOG_COLOR

to

PIXEL_COLOR = exp(-d/(D+GGG)) * OBJECT_COLOR + (1-exp(-d/(D+GGG))) * FOG_COLOR

Where GGG= an infitesimal, just bigger than the smallest number pov can handle

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