POV-Ray : Newsgroups : povray.pov4.discussion.general : Brainstorming: portals : Re: Brainstorming: portals Server Time
2 Dec 2021 13:59:20 EST (-0500)
  Re: Brainstorming: portals  
From: Trevor G Quayle
Date: 27 Mar 2013 17:05:01
Message: <web.51535de8b5e68db581c811d20@news.povray.org>
"Simon Copar" <inf### [at] gmailcom> wrote:
> Just an idea to think about: what if there was a pigment, that instead of giving
> off color, it would transport and rotate the incoming ray? This would have
> multiple uses:
> 1) move and rotate the ray somewhere else and re-sample it. This would allow to
> define surfaces that act as portals/windows into another part of the scene.
> 2) keep the origin, but perturb the direction. This way, a user could reproduce
> any effect involving irregular reflections (normal perturbation) and
> refractions, but with more control (such as using the input ray information as a
> parameter for generating the external ray)
> 3) the portal idea can be used to simulate stuff like pictures and TV screens
> (and crystal balls) that render another part of the scene. Possibly, you could
> have a warp, that would transform rays, falling on the TV screen into rays that
> exit a camera, creating the "TV is showing picture of itself" effect.
> 4) Strange universe boundary conditions (make such a universe, that a ray that
> hits a sphere at a large distnace comes back at you from behind). Very useful
> for mathematical abstract art.
>
> So, we have a single feature that allows a lot of different imaginative and
> artistic effects that are not possible otherwise. Infinite recursion is
> prevented by max_trace_depth.
>
> In essence, you have a user-defined function that takes input ray in the form
> (location,direction) and returns another (location,direction).

megapov had the camera_view pigment type which could do a lot of this
(http://megapov.inetart.net/manual-1.2.1/megapov0121.html#camera_view)
It never got carried over into the official POVRay.
I had used in the past for various things such as creating one-pass stereograph
images.

-tgq


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