Zeger Knaepen wrote:

 > And if it is possible that it intersects, maybe that's reason
 > enough to supersample the pixel?  I mean: you don't have to find
 > the intersecting points, maybe you don't even have to find out if
 > there is an intersection.  I might be enough to know there is no
 > intersection, and maybe that's easy to find out?  I'm not very
 > good in mathematics, so I'm probably just talking nonsense...
 >

To put it in a wierd way: what you request is allmost that what povray
does. The only difference beeing: povray's AA triggers on color
changes, not on ray-hits-different-object.
After a "trigger condition" is detected, a search process startes by
shooting more and more rays to get the location of the trigger
condition more precise.

That means: one could consider to change povray, so that it starts AA,
if the next intersection hit on a different object than the previous
one. But in most cases, detection of object changing is a weaker
condition than detecting a color change (because the latter can also
happen by texturing, lighting or media). So, if color-change-triggerd
AA is not satisfactory in some cases, I would guess, 
object-change-triggerd AA will be as well not satisfactory in
even more cases.

Maybe it will detect the border of a black cat in the night :-)

So, maybe the best way would be, to go on and hack povray
to try it out.

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