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Consider a simple cube as
superellipsoid{ <.25,0.25>
texture{ pigment{ color rgb<0.65,1,0.1>}
finish { phong 1}
}
I put an image on its surface as
superellipsoid{ <.25,0.25>
texture{ pigment{
image_map{ png "ad.png"
map_type 0
interpolate 2
once
}
}
finish { phong 1}
}
}
I have two problems:
1. How can I keep the pigment color underneath to have a closed where has not
been wrapped by the image?
2. Wrapping starts from the left corner of the object, and I lose the curvature
on the left side, but it is OK on the right side. According to
http://www.f-lohmueller.de/pov_tut/backgrnd/p_sky9.htm the image covers +Z and
goes to +X. Is it possible to put the image on the center of +Z to let the
excess image covers both -X and +X?
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From: William F Pokorny
Subject: Re: How to put image on one side of an object
Date: 5 Aug 2019 07:58:18
Message: <5d4819da$1@news.povray.org>
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On 8/4/19 2:55 PM, Kima wrote:
> Consider a simple cube as
>
> I have two problems:
>
> 1. How can I keep the pigment color underneath to have a closed where has not
> been wrapped by the image?
>
> 2. Wrapping starts from the left corner of the object, and I lose the curvature
> on the left side, but it is OK on the right side. According to
> http://www.f-lohmueller.de/pov_tut/backgrnd/p_sky9.htm the image covers +Z and
> goes to +X. Is it possible to put the image on the center of +Z to let the
> excess image covers both -X and +X?
>
If I'm understanding your questions,
With (1) the object pattern is perhaps one way where you use another
unseen/defined-only object along with a second solid color texture to
limit where the image_map texture is applied.
With (2) move the image_map using translate <-0.5,-0.5,0>. You'll likely
still not get the ideal map to the curvature for the superellipsoid at
the corners. I don't know how to easily correct for that distortion.
Aside: For some shapes there is the shape uv_mapping mechanism(1), but
as I recall the superellipsoid isn't supported. Further, there are today
general issues with it even for shapes where it is implemented.
A question bouncing around in my head is whether with the new
user_defined camera there isn't some way we can implement a more general
3D point to shape mapping mechanism. I have a crude version of the idea
going in my density file patch branch. It's how the warps of the posted
maze images warped both the iso-surface shape and it's texture(s)
together. Not sure though how to do the point to surface association and
interpolation generally for any shape including csg - but that's sort of
the thought.
Bill P.
(1) - Not here speaking of the image_map or warp type mapping.
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Le 04/08/2019 à 20:55, Kima a écrit :
> Consider a simple cube as
>
> superellipsoid{ <.25,0.25>
> texture{ pigment{ color rgb<0.65,1,0.1>}
> finish { phong 1}
> }
>
> I put an image on its surface as
>
>
> superellipsoid{ <.25,0.25>
> texture{ pigment{
>
> image_map{ png "ad.png"
> map_type 0
> interpolate 2
> once
> }
>
> }
> finish { phong 1}
> }
>
> }
>
> I have two problems:
>
> 1. How can I keep the pigment color underneath to have a closed where has not
> been wrapped by the image?
>
> 2. Wrapping starts from the left corner of the object, and I lose the curvature
> on the left side, but it is OK on the right side. According to
> http://www.f-lohmueller.de/pov_tut/backgrnd/p_sky9.htm the image covers +Z and
> goes to +X. Is it possible to put the image on the center of +Z to let the
> excess image covers both -X and +X?
>
>
what about using a "warp{ cubic }" ?
http://wiki.povray.org/content/Reference:Warp#Mapping_using_warps
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Le_Forgeron <jgr### [at] free fr> wrote:
> what about using a "warp{ cubic }" ?
>
> http://wiki.povray.org/content/Reference:Warp#Mapping_using_warps
I must admit, that I have never used this, neither can I find a graphical
example of what it looks like.
I'm also presuming that it's different from the cubic pigment pattern
http://news.povray.org/povray.binaries.images/thread/%3C5a66fe3d%241%40news.povray.org%3E/
Given the fact that I've been investigating and experimenting more with
functions and patterns, this also makes me wonder how hard it would be to make a
superellipsoid warp.
http://povray.org/documentation/view/3.6.1/285/
Based upon a cursory reading of this (pg 19):
https://cse.buffalo.edu/~jryde/cse673/files/superquadrics.pdf
It seems to me that perhaps a modification of the spherical warp might be the
way to go?
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> Given the fact that I've been investigating and experimenting more with
> functions and patterns, this also makes me wonder how hard it would be to make a
> superellipsoid warp.
Placing this here for future investigation:
https://github.com/baonguyen84/SuperQuadric-Webgl
"This program is a html file using WebGL, built on JavaScript that first build a
surface of of superellipsoid. .... Finally the program will map a 2D texture, by
dividing up the mesh into "slices and dices", map an image to the corresponding
point on the surface of the mesh...."
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Placing this here as well for future investigation:
https://cs-people.bu.edu/sbargal/Fall%202016/lecture_notes/Nov_3_3d_geometry_representation
(page 20)
If it has a parametric equation based on u and v, is it then not inherently
uv-mappable?
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And
(1) since this appears to be a _fait accompli_ in 1998,
https://www.academia.edu/10284037/Surface_subdivision_for_generating_superquadrics
(2) it would be educational for many people to see the mechanism of how
uv-mapping is applied to a shape,
and
(3) isosurfaces and parametrics can be a real bear to even get to display
properly,
Perhaps we can open up a new thread on uv mapping Superquadrics, with a suitable
test scene in SDL, and a
pigment {function(x,y,z, RX, RY, RZ, E1, E2){Equation}}
can be defined to texture the surface of the object.
At the moment, I can't get the parametric to give me anything but a completely
black box even with an emissive red texture, and my isosurface doesn't even show
up :(
Ray->Shape Intersection Tests Succeeded Percentage
----------------------------------------------------------------------------
Isosurface 262203 0 0.00
Isosurface Container 262257 262257 100.00
Isosurface Cache 189211 32172 17.00
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