POV-Ray: Newsgroups: povray.advanced-users: coordinates of shadow

POV-Ray : Newsgroups : povray.advanced-users : coordinates of shadow		Server Time 1 Jul 2024 05:49:14 EDT (-0400)

From: Luiz
Subject: coordinates of shadow
Date: 3 Apr 2009 21:10:03
Message: <web.49d6b2c9c8395b66981462dc0@news.povray.org>

Hello everybody,

I wonder if it is possible to somehow get the coordinates of a shadow... let me
explain:

I build sundials, and povray could be very useful in planning, using sunpos.inc
which comes with povray. If I, for instance have a sphere floating over a
plane, would it be possible to get the coordinates of the center of the shadow
of the sphere on the plane?

Thanks,
Luiz

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From: Mike Williams
Subject: Re: coordinates of shadow
Date: 3 Apr 2009 21:31:43
Message: <NCqVm+D5hr1JFwm7@econym.demon.co.uk>

Wasn't it Luiz who wrote:
>Hello everybody,
>
>I wonder if it is possible to somehow get the coordinates of a shadow... let me
>explain:
>
>I build sundials, and povray could be very useful in planning, using sunpos.inc
>which comes with povray. If I, for instance have a sphere floating over a
>plane, would it be possible to get the coordinates of the center of the shadow
>of the sphere on the plane?

You should be able to use trace() to trace a ray:
   to the plane
   from the position of the light source
   in the direction of (sphere centre minus position of light source)

-- 
Mike Williams
Gentleman of Leisure

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