> In POVRay, if using a spotlight, the shadows are perfectly defined. We
> all know in real life this doesn't happen, due to the diffraction of
> light as it passes an interface between two media. Of course, POVRay
> deals with the particular nature of light, not the wave nature, so how
> do we get it to blur shadows according t distance from casting object
> without resorting to area lights?
>
> Cheers,
> James Jackson.

Well, I'd hate to get all technical on you here but...

First, as the others have said, use an area_light - read the docs for a
decent discussion on how to get good shadows.

Second, diffraction is caused by light passing through a finite space
(waves perfectly retain their shape only when completely unobstructed),
for example a thin slit (causes the emergent light to spread out) or
passing "round" an obstruction (causes the light to bend "round" the
object).  I think you're getting confused with refraction here - the
changing of the direction of light at an interface - something
completely different which POV handles admirably nonetheless.

Third (and I'm being pedantic here :-) I think POV deals with the *ray*
nature of light rather than waves or particles.  Waves have horrible
things like diffraction to cope with, and particles are subject to the
messy laws of quantum mechanics.

But area_lights avoid all this nonsense...

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