"Thomas de Groot" <t.d### [at] internlnet> wrote:
> IMHO it has to do with the fog. As far as I remember (version 3.1) there
> always was a problem with fog used in combination with a texture showing
> transparant parts (alpha channel or otherwise).

I started looking at the source code, trying to find out what's going on...

It seems like, when the renderer computes the shadow of a (partly, or
completely) transparent object, it takes into account the fog between the
light source and the shadow. If there is fog, it attenuates the light
coming from the light source, and as a result the shadow becomes a bit
darker. This even happens if the object is completely transparent and
hollow, resulting in a visible shadow when there should be none.

IMHO this is a bug. If fog should attenuate light coming from a light
source, it should happen for the whole scene, not just the shadows of
transparent objects. Either that, or fog shouldn't affect light source rays
at all.

I was able to compile a version which renders the scene in my original post
correctly, but it was a rather quick hack and I'm not sure if it has any
side effects, so I'll look into it some more.

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