"Philipp" <pov### [at] phipracom> wrote:
> Hi,
>
> I am considering to dig into PovRay, if it can do what I need - so I hope
> that someone of you can tell me whether it will:
>
> A light source (the sun) shines on a reflecting surface (say, a
> square-shaped mirror that is hanging on a wall). As the sunlight comes from
> above and shines onto the mirror, part of the sunlight is reflected
> downwards to the floor. Thus, a basically parallelogram-shaped lighter area
> should be visible on the floor.
>
> I then would like to determine when (date and time of the day) the reflected
> sunlight falls on a certain area of the floor (or objects). It need not be a
> realistic rendering - I just want to determine the days in the year when the
> reflected sunlight hits an object that sits on the floor.
>
> To my understanding, this should be possible by using photon mapping, and
> then trying to make a fast-motion video from it. Is that correct, and is it
> feasable for, say, a hobby programmer to do this within two working weeks?
>
> (Is there some module or code-snippet for automatically calculating the
> sun's position, given geographical position and date/time?)
>
>
> Many thanks!
> Philipp

I hate to say so, since one more Povver is obviously good in the greater
scheme of things, ;-) but you don't need to use POV at all to do that.
Simply calculate the angle from the object to the mirror, then determine
where the sun should be in the sky. You may want to convert that to Right
Ascension and Declension (or whatever they're called in English), just
google it. Then look up ephemerides (for example
http://cfa-www.harvard.edu/iau/MPEph/MPEph.html)

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