POV-Ray : Newsgroups : povray.binaries.images : Mapping images onto prisms? Server Time
9 Aug 2024 13:23:49 EDT (-0400)
  Mapping images onto prisms? (Message 1 to 4 of 4)  
From: Tom York
Subject: Mapping images onto prisms?
Date: 12 Jan 2005 04:45:01
Message: <web.41e4f03585e3d9842ff34a90@news.povray.org>
I have a complicated model made up of a large number of POV primitives,
including prisms. I've run into problems when trying to apply a bitmap
image to many of these primitives, because the available mappings always
seem to introduce distortion somewhere (except on cylinders and spheres,
obviously).

At present I'm concentrating on mapping bitmaps onto prisms - the attached
image shows a small element that is mostly made up from prisms. The blue
highlighted objects are prisms that I'm particularly stuck on. The prisms
making the central body of the object have lots of obscured surfaces, so I
could probably put up with the "streaks" caused by a planar mapping.
However, the highlighted prisms have four or five very exposed sides, so a
planar mapping will look fine on two of the sides but terrible on the
others. A cylindrical or spherical mapping will introduce lots of
distortion and make drawing the textures quite difficult. I am not sure
what to try next. I'd quite like to keep any workaround simple (or at
least reasonably fast) as I intend to use the model in animations. I
couldn't find mention of UV mapping support for prisms in POV 3.6 - did I
miss it?


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Attachments:
Download 'mt.jpg' (14 KB)

Preview of image 'mt.jpg'
mt.jpg


 

From: Tim Nikias
Subject: Re: Mapping images onto prisms?
Date: 12 Jan 2005 04:48:22
Message: <41e4f266$1@news.povray.org>
AFAIK, there is no UV-mapping support for pov-primitives. The only real
uv-mapping is applied to meshes.

What you could do, however, and which shouldn't be too difficult, is write a
small macro which converts your prism control-points to a mesh with
uv-mapping. Solid prisms are really trivial, it get's worse of course when
you get into holes and such. With a little arithmetic you should be able to
calculate and inside_vector for your mesh, so that you can use it with
simple CSG-instructions, but maybe that's already overkill...

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>


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From: ABX
Subject: Re: Mapping images onto prisms?
Date: 12 Jan 2005 04:52:06
Message: <dns9u05bjlgfb1d0osu46b51d3100fg80i@4ax.com>
On Wed, 12 Jan 2005 04:40:19 EST, "Tom York" <alp### [at] zubenelgenubi34spcom>
wrote:
> I am not sure what to try next.

Next try prism-like mesh with uv coordinates as in
http://members.home.nl/seedseven/#prism

ABX


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From: Tom York
Subject: Re: Mapping images onto prisms?
Date: 15 Jan 2005 11:25:01
Message: <web.41e943763087e7962ff34a90@news.povray.org>
Thanks! UV mapping worked well on boxes and lathes, so I hoped there was
something similar for prisms. But if a mesh is the best solution then I
will redo the offending components in Wings, since this will solve a
further problem I had with bevelling edges as well.


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