POV-Ray : Newsgroups : povray.general : How to put image on one side of an object Server Time: 19 Aug 2019 14:10:34 GMT
 How to put image on one side of an object (Message 1 to 7 of 7)
 From: Kima Subject: How to put image on one side of an object Date: 4 Aug 2019 19:00:00 Message:
```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{

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?
```
 From: William F Pokorny Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 11:58:18 Message: <5d4819da\$1@news.povray.org>
```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?
>

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.
```
 From: Le Forgeron Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 17:18:55 Message: <5d4864ff\$1@news.povray.org>
```Le 04/08/2019 Ã  20:55, Kima a Ã©critÂ :
> 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{
>
>             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
```
 From: Bald Eagle Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 18:30:00 Message:
```Le_Forgeron <jgr### [at] freefr> 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

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):

It seems to me that perhaps a modification of the spherical warp might be the
way to go?
```
 From: Bald Eagle Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 18:40:01 Message:
```"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:

"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...."
```
 From: Bald Eagle Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 18:50:00 Message:
```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?
```
 From: Bald Eagle Subject: Re: How to put image on one side of an object Date: 5 Aug 2019 20:15:00 Message:
```And

(1) since this appears to be a _fait accompli_ in 1998,
(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
```