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29 Jul 2024 20:22:23 EDT (-0400)
  Mesh with an image pigment (Message 1 to 5 of 5)  
From: Sam Takoy
Subject: Mesh with an image pigment
Date: 28 Jun 2010 15:50:00
Message: <web.4c28fc144b67401c858afefa0@news.povray.org>
Hi,

I have a complicated deformed mesh. Is there documentation on how to texture it
with an image? (It is a "topological" rectangle that looks like a hanging table
cloth.)

Many thanks in advance,

Sam


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From: clipka
Subject: Re: Mesh with an image pigment
Date: 28 Jun 2010 18:14:02
Message: <4c291eaa$1@news.povray.org>
Am 28.06.2010 21:46, schrieb Sam Takoy:

> I have a complicated deformed mesh. Is there documentation on how to texture it
> with an image? (It is a "topological" rectangle that looks like a hanging table
> cloth.)

"UV mapping" is what you'll want to have a look at. You'll have to 
assign 2D coordinates (termed U and V) to the vertices of each triangle 
in the mesh, thereby specifying the triangle's position in 2D "image space".


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From: Sam Takoy
Subject: Re: Mesh with an image pigment
Date: 28 Jun 2010 22:30:01
Message: <web.4c2959b3ff9663a1858afefa0@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 28.06.2010 21:46, schrieb Sam Takoy:
>
> > I have a complicated deformed mesh. Is there documentation on how to texture it
> > with an image? (It is a "topological" rectangle that looks like a hanging table
> > cloth.)
>
> "UV mapping" is what you'll want to have a look at. You'll have to
> assign 2D coordinates (termed U and V) to the vertices of each triangle
> in the mesh, thereby specifying the triangle's position in 2D "image space".

Thank you.

It seems that if I only have a single triangle in a mesh, it will sample three
points from the image and interpolate from those three values. Rather than keep
looking at the pixels in the image and place those pixels in the right place in
the triangle. Am I correct? (I hope not.)


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From: Sam Takoy
Subject: Re: Mesh with an image pigment
Date: 29 Jun 2010 02:50:01
Message: <web.4c2996d1ff9663a1858afefa0@news.povray.org>
"Sam Takoy" <sam### [at] yahoocom> wrote:
> clipka <ano### [at] anonymousorg> wrote:
> > Am 28.06.2010 21:46, schrieb Sam Takoy:
> >
> > > I have a complicated deformed mesh. Is there documentation on how to texture it
> > > with an image? (It is a "topological" rectangle that looks like a hanging table
> > > cloth.)
> >
> > "UV mapping" is what you'll want to have a look at. You'll have to
> > assign 2D coordinates (termed U and V) to the vertices of each triangle
> > in the mesh, thereby specifying the triangle's position in 2D "image space".
>
> Thank you.
>
> It seems that if I only have a single triangle in a mesh, it will sample three
> points from the image and interpolate from those three values. Rather than keep
> looking at the pixels in the image and place those pixels in the right place in
> the triangle. Am I correct? (I hope not.)

As a follow up, here is he image:

http://freeboundaries.com/Equations.png

and here is the pov ray result

http://freeboundaries.com/pov.png

Thank you very much in advance.


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From: Slime
Subject: Re: Mesh with an image pigment
Date: 29 Jun 2010 03:36:50
Message: <4c29a292$1@news.povray.org>
> It seems that if I only have a single triangle in a mesh, it will sample three
> points from the image and interpolate from those three values. Rather than keep
> looking at the pixels in the image and place those pixels in the right place in
> the triangle. Am I correct? (I hope not.)

You are incorrect. It interpolates the (u,v) coordinates, and samples 
the image separately for each pixel on the triangle.

  - Slime


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