On Fri, 20 May 2005 20:52:03 +0200, Tim Nikias wrote:

>> Is there a way in POV-Ray to make projections from a point? Maybe it's
>> possible to design something that does this manually ...
> 
> What you're describing is what POV-Ray is doing. You define an array of
> lights in arealights. It begins with the first four in the corners: if all
> are shadowed, the pixel is considered in shadow. The adaptive step sets a
> minimum limit of corners to check (note that adaptive 1 will check 9 points:
> four in the corners, then every between the corners). Look it up in the
> documentation, I'm a little lazy to write it all out. :-P

Yes, I had already read the documentation about it :) but I was
thinking about some more analytical process. After all, most POV-Ray
shapes have almost-everywhere-analytical boundaries, so it should be
possible to calculate their projection on a plane (the plane of the
light as seen by the point whose shadow has to be calculated), its
intersection with the area light (the "true" one, not the discretized
version) and the calculate the area of the visible part of the light.

Or would this be too expensive?

-- 
Giuseppe "Oblomov" Bilotta


"A me me la compra il mio babbo"
(Altan)
("When I grow up, I will fight for peace"
 "I'll have my daddy buy it for me")

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