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  Replacing a sky_sphere with a cylinder. (Message 1 to 8 of 8)  
From: Ephphatha
Subject: Replacing a sky_sphere with a cylinder.
Date: 25 Aug 2006 08:45:00
Message: <web.44eeefebc4397441fba358d80@news.povray.org>
I know this is a stupid question, but I haven't found how to change it yet
in the documentation.

At the moment, I have this:

// Create an infinite sphere around scene and allow any pigment on it
sky_sphere {
  pigment {
    gradient z
    color_map { [0.0 color rgb <180/255,230/255,255/255>] [1.0 color blue
0.5] }
  }
}

I know how to put an image on it, that's no problem. I want it to be a
cylinder though so I can put a tiled image of a forest on it that will
repeat side by side, but not stack. I hope I'm making sense here. Can
someone help?


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From: Trevor G Quayle
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 25 Aug 2006 09:20:01
Message: <web.44eef86a84f946e0c150d4c10@news.povray.org>
"Ephphatha" <nomail@nomail> wrote:
> I know this is a stupid question, but I haven't found how to change it yet
> in the documentation.
>
> At the moment, I have this:
>
> // Create an infinite sphere around scene and allow any pigment on it
> sky_sphere {
>   pigment {
>     gradient z
>     color_map { [0.0 color rgb <180/255,230/255,255/255>] [1.0 color blue
> 0.5] }
>   }
> }
>
> I know how to put an image on it, that's no problem. I want it to be a
> cylinder though so I can put a tiled image of a forest on it that will
> repeat side by side, but not stack. I hope I'm making sense here. Can
> someone help?

This is not strictly possible, as the sky_spere has no actual dimensions,
basically if a ray misses everything else, the sky sphere is evaluted at
that ray.  Fowhat you want to do, perhaps look at either cylindrical
mapping onto the sky_sphere or using an actual cylinder, scaled large
enough for what you want it to look like.  The latter may be the best
option, as it allows you to have a sky_sphere beyond and above the forest
as well.

-tgq


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From: Ephphatha
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 25 Aug 2006 20:20:01
Message: <web.44ef934184f946e0fba358d80@news.povray.org>
"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
>
> This is not strictly possible, as the sky_spere has no actual dimensions,
> basically if a ray misses everything else, the sky sphere is evaluted at
> that ray.  Fowhat you want to do, perhaps look at either cylindrical
> mapping onto the sky_sphere or using an actual cylinder, scaled large
> enough for what you want it to look like.  The latter may be the best
> option, as it allows you to have a sky_sphere beyond and above the forest
> as well.
>
> -tgq
Can't believe I didn't think of that, thank you. It is possible to put a
cylinder in that encompasses the whole scene and the texture will be shown
on the inside?


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From: Thomas de Groot
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 26 Aug 2006 03:18:44
Message: <44eff5d4$1@news.povray.org>
"Ephphatha" <nomail@nomail> schreef in bericht 
news:web.44ef934184f946e0fba358d80@news.povray.org...
> Can't believe I didn't think of that, thank you. It is possible to put a
> cylinder in that encompasses the whole scene and the texture will be shown
> on the inside?
>
Yes.
Don't forget to make the cylinder hollow, otherwise you will get a warning, 
and other things may not work, like fog.

Thomas


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From: Warp
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 26 Aug 2006 04:56:28
Message: <44f00cbc@news.povray.org>
Thomas de Groot <t.d### [at] internlnet> wrote:
> Don't forget to make the cylinder hollow, otherwise you will get a warning, 
> and other things may not work, like fog.

  How about making it 'inverse' instead?

-- 
                                                          - Warp


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From: Thomas de Groot
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 28 Aug 2006 08:14:00
Message: <44f2de08$1@news.povray.org>
"Warp" <war### [at] tagpovrayorg> schreef in bericht 
news:44f00cbc@news.povray.org...
> Thomas de Groot <t.d### [at] internlnet> wrote:
>> Don't forget to make the cylinder hollow, otherwise you will get a 
>> warning,
>> and other things may not work, like fog.
>
>  How about making it 'inverse' instead?
>

Yes, of course! Forgot about that extremely useful possibility!!!

Thomas


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From: Mike Sobers
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 29 Aug 2006 11:50:00
Message: <web.44f460fb84f946e01009749b0@news.povray.org>
Warp <war### [at] tagpovrayorg> wrote:
> Thomas de Groot <t.d### [at] internlnet> wrote:
> > Don't forget to make the cylinder hollow, otherwise you will get a warning,
> > and other things may not work, like fog.
>
>   How about making it 'inverse' instead?
>
> --
>                                                           - Warp

Is 'inverse' better than 'hollow'?  Enlightenment, please.

Also, you should check out this thread in the p.general on repeating
patterns:

http://news.povray.org/povray.general/thread/%3C44e91914%241%40news.povray.org%3E/

Mike


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From: Alain
Subject: Re: Replacing a sky_sphere with a cylinder.
Date: 29 Aug 2006 19:00:26
Message: <44f4c70a$1@news.povray.org>
Mike Sobers nous apporta ses lumieres en ce 29/08/2006 11:45:
> Warp <war### [at] tagpovrayorg> wrote:
>> Thomas de Groot <t.d### [at] internlnet> wrote:
>>> Don't forget to make the cylinder hollow, otherwise you will get a warning,
>>> and other things may not work, like fog.
>>   How about making it 'inverse' instead?
>>
>> --
>>                                                           - Warp
> 
> Is 'inverse' better than 'hollow'?  Enlightenment, please.
> 
> 
> Mike
> 
> 
Better,no, different, yes. They serve different purpose, but in some cases are 
interchangeable.
Hollow make it possible to have media or fog to fill the object.
Inverse invert the interiorness of the object. What is inside the object is 
considered outside of it. It was originaly created to make intersections before 
the intersection was implemented. You'd do a difference of an object and the 
inverse of the other.
In a scene with fog or uncontained media, an hollow object and the rest of the 
scene will contain the media. The same scene but with inverse, the media/fog 
will only exist inside the object.

-- 
Alain
-------------------------------------------------
To the world you may be one person, but to one
person you may be the world.


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