Burton Radons <lot### [at] pacificcoastnet> wrote ...
> Nieminen Juha wrote:
> >
> > Burton Radons <lot### [at] pacificcoastnet> wrote:
> > : This solution would only compound the problem.  If you let the ray
> > : ignore the first intersection, then it will be inside the sphere and
> > : simply hit the other side going out, causing the same problem as
> > : before.
> >
> >   The solution was precisely to ignore that surface (ie. the first
intersection
> > with the current object from the current point). So there's no such
problem.
>
> Sorry.  I was thinking of the first intersection as being the surface,
> and therefore the cause of the shadow, but with the epsilon it should
> pass through the intersected surface and hit the other side of the
> object.  And of course, the surface is already taken into account for
> the coloring and doesn't need to be filtered twice.
>
> I can't think of any reason why your technique would fail.

Actually, you brought up a good point. Media calculations (which have to
know whether a ray is inside or outside of a particular interior), and the
translucency calculations WOULD get confused by ignoring the first
intersection.  However, with fully-opaque objects, this should work.  Using
it as an option then allows users to apply it only in situations where it
would not cause strange problems.

Actually implementing this could prove quite difficult, unfortunately (due
to the shadow cache and the bounding box tree which have been implemented to
speed up shadow calculations).

-Nathan

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