POV-Ray : Newsgroups : povray.newusers : image_map to tilted and rotated triangle centered and scaled : Re: image_map to tilted and rotated triangle centered and scaled Server Time
6 Jul 2022 17:48:15 EDT (-0400)
  Re: image_map to tilted and rotated triangle centered and scaled  
From: Tor Olav Kristensen
Date: 28 Mar 2022 09:35:00
Message: <web.6241b916ccfe2900702815af89db30a9@news.povray.org>
"Molly-J" <nomail@nomail> wrote:
> I am going mad trying to project image maps onto polygons that are not in the
> x-y plane or plumb to the y axis. I have 20 equilateral triangles forming a
> typical D20 shape (regular icosahedron). I have the XYZ coordinates for the
> points so all I have to do is create each triangle using sets of the 32
> vertices. BUT . . . .
>
> I cannot work out how to project the 20 image_map pigments properly. Image_map
> pigments only seem to work on polygons normal to the Z axis and left corner at
> 0,0 XY
>
> The suggestion that I create each triangle at 0,0 and then translate/rotate them
> to the icosahedron would be just fine if i had those numbers. (I do not)
>
> There must exist another way, as the current limitation is ludicrously
> un-useful. Everybody aplying pictures to polyhedra would have exactly the same
> problem.
> What am I missing?
>
> Is it possible to translate the triangle by translating its individual points?
> That I might be able to do, but I can't work out how.
>
>
> The ultimate goal is a Dymaxion type world map on an Icosahedron.

Hi Molly

Perhaps the code I posted in this thread can be useful for you:

From: Tor Olav Kristensen
Subject: How to transform a triangle into another
Date: 2002-10-02 19:41:55
http://news.povray.org/povray.text.tutorials/thread/%3C3D9B843D.E5392CD0%40hotmail.com%3E/

If so, then it is important to replace the 4 first lines in the
Triangle2Triangle_Trans macro (and probably in the Pyramid2Pyramid_Trans macro)
with the corrected ones in my second post.

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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