POV-Ray : Newsgroups : povray.binaries.misc : transformation matrix : Re: transformation matrix Server Time
18 Jun 2021 02:23:58 EDT (-0400)
  Re: transformation matrix  
From: Bald Eagle
Date: 25 Dec 2018 14:25:01
Message: <web.5c2283baa8b241df765e06870@news.povray.org>
"jr" <cre### [at] gmailcom> wrote:
> hi,
>
> the documentation for the transformation matrix says: "... you will not use the
> matrix keyword because it is ... harder to visualize."  however, although
> "mathematically challenged", I'd like to learn to use it on occasion.
>
> that in mind, can someone please explain why the manual (3.3.1.12.4) mentions a
> "..fourth column implicitly set to <0,0,0,1>..", but the subsequent equations do
> not include/use those values.

Because all of those things are affine transform matrices.

IIRC, those other numbers change when you start to use projection matrices and
other transformations.

See:

http://www.scratchapixel.com/lessons/3d-basic-rendering/perspective-and-orthographic-projection-matrix/projection-matri
ces-what-you-need-to-know-first

http://news.povray.org/povray.general/thread/%3Cweb.5b9ed475f76fb4baa47873e10%40news.povray.org%3E/


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