POV-Ray : Newsgroups : povray.advanced-users : Mesh2 and image maps : Re: Mesh2 and image maps Server Time
26 Feb 2024 07:17:11 EST (-0500)
  Re: Mesh2 and image maps  
From: Leroy
Date: 6 Mar 2020 22:10:00
Message: <web.5e630f6e6524ec49f7d4608f0@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:
> >
> Hi Leroy,
> Not here. Perhaps someone using meshes regularly understands why you see
> what you see. I'll offer guesses/rambling in the meantime - while having
> a feeling you are using the mesh uv mapping mechanism in a somewhat
> unusual way.

First off I want to apologize for being so late getting back here.
 And you need to know that as soon as I got off line I found the problem was all
in the way I used the image map. Before I did my 'fix' I had the uv fitted to
the mesh in a 1 to belt length style <0,0> to <1,Belt length> so any image would
fit the belt.
 After the 'fix' it was <0,0> to <1,1>, While testing, I plane forgot what I
just did and was scaling the image map to fit the old style of uv mapping.
Now I didn't use the once in the image map, so I got repeat images. And my test
values to move the texture just happen to keep the image map in the same place
but the normals where where moved!
 So now we have an new effect. When the image is frozen and the normals move you
can have gost floating across the screen. My test image was a landscape and it
made it look like clouds floating over head.

> - In my experience the mesh image maps would point into the image,
> texture or material with uv vectors in some sort of fixed / one time
> way.
Your completely  right there.

> - When you say you've set the uv vectors in the mesh, I assume you mean
> you are pointing mesh vertexes at the appropriate locations in the BTexX
> texture. I suppose you're aligning those with the gradient y in some
> fashion(1).
I'll answer this here and drop (1)
Your Right in what I did. I wrapped the uv mapping around a belt so that each
face of the belt match one of the textures in BTexX.

> I've played with meshes in mapping other formats into POV-Ray and doing
> simple stuff color to vertex stuff, but, my understanding of how the
> POV-Ray uv mesh mechanism 'really works' is shallow(2).
> Bill P.
> (2) - With mesh image mapping, wondered how the mesh mapping pros handle
> an image's interpolation seams. Are appropriate extra pixels carefully
> added to the images internal edges/cut-outs to be sure any 'image'
> interpolation results in a clean texture on the mesh at those seams?
> Does such a thing happen by side effect of mesh painting - is there some
> overspray area? I'm curious if anyone knows - otherwise, someday maybe
> I'll investigate. You've mapped without POV-Ray image interpolation /
> smoothing, so my question matters not in your scene.

 I haven't used many other Mesh making programs. Blender the one that comes to
mind and I never did get into the image mapping part. I have seen some of the
images used by other Mesh programs. They are always tied to a single mesh.

Thanks for you thoughts.
Have Fun

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