Hi all,

An easy question:

I want to add color modifiers as granite, finish and normal in a sky_sphere. 
Is it possible?

Some code:
======================================
sky_sphere {
    pigment {

     gradient y
      color_map {
       [ 0.5  color CornflowerBlue ]
        [ 1.0  color MidnightBlue ]


      }
      scale 2
      translate -1
    }
  }
======================================

Could be something like:
======================================
pigment { scale 0.1 granite color_map { [0.5 color CornflowerBlue] [1 color 
MidnightBlue] } }
finish { specular 1 roughness 1/100 reflection { 0.05, 0.5 fallof 3.5 } }
normal { ..... }
======================================

How can I  put the code into the sky_sphere?

Thanks in advance,
Oleguer

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Oleguer Vilella <ole### [at] infonegociocom> wrote:
> I want to add color modifiers as granite, finish and normal in a sky_sphere. 

  Finish and normal would make no sense in a sky_sphere because a
sky_sphere is not an object and is not illuminated by any light source.

  Basically, a sky_sphere is a pigment, no more, no less. When a ray
does not hit anything, then the color for that ray is taken from that
pigment depending on the direction of the ray (and depending only on
that; eg. the starting point of the ray has no effect).

  Thus rays do not hit the sky_sphere (because it's not an object),
intersection calculations are not done, reflected/refracted rays are
not calculated, illumination is not calculated. There can't be
anything "behind" the sky_sphere and nothing, absolutely nothing
can interact with it.

  If you want a real object, then use a big inverted sphere centered
at the camera location.

-- 
                                                          - Warp

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Wasn't it Oleguer Vilella who wrote:
>Hi all,
>
>An easy question:
>
>I want to add color modifiers as granite, finish and normal in a sky_sphere. 

The sky_sphere takes a pigment, not a texture, so you can't have a
normal or a finish.

You could replace it with a sufficiently large sphere, in which case
also consider whether you also need to use finish {ambient 1},
no_shadow, and hollow. The sky_sphere object automatically has the
equivalent of those settings, but if you need them on a sphere object
you have to remember to specify them.

-- 
Mike Williams
Gentleman of Leisure

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Mike Williams <nos### [at] econymdemoncouk> wrote:
> and hollow

  Inverse, inverse, inverse.

  "Inverse" must be the least-used keyword in the whole povray, for
some reason.

> The sky_sphere object automatically has the
> equivalent of those settings

  It's a bit difficult to say that it "has" anything, because the
sky_sphere is not an object and can't have any object properties
whatsoever. Basically sky_sphere is a pigment, nothing more,
nothing less. A pigment cannot have "no_shadow", "finish",
"hollow", "inverse" or anything like that.

-- 
                                                          - Warp

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Hi Warp and Mike,

First of all happy new year!

So, a sky_sphere is not an object and I can't use object modifiers.

Yeah, using a big sphere centered at the camere location like Warp says 
should work properly.

Thanks for your time,
Oleguer







news:43ba4658@news.povray.org...
> Mike Williams <nos### [at] econymdemoncouk> wrote:
>> and hollow
>
>  Inverse, inverse, inverse.
>
>  "Inverse" must be the least-used keyword in the whole povray, for
> some reason.
>
>> The sky_sphere object automatically has the
>> equivalent of those settings
>
>  It's a bit difficult to say that it "has" anything, because the
> sky_sphere is not an object and can't have any object properties
> whatsoever. Basically sky_sphere is a pigment, nothing more,
> nothing less. A pigment cannot have "no_shadow", "finish",
> "hollow", "inverse" or anything like that.
>
> -- 
>                                                          - Warp

Post a reply to this message

In article <43ba434b@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

> Oleguer Vilella <ole### [at] infonegociocom> wrote:
> > I want to add color modifiers as granite, finish and normal in a 
> > sky_sphere. 
> 
>   Finish and normal would make no sense in a sky_sphere because a
> sky_sphere is not an object and is not illuminated by any light source.

Though it could define a normal as being the vector opposite to the ray 
direction. I am not sure about the usefulness of doing so, however...the 
"normal" would always be antiparallel to the ray direction, no matter 
what direction the ray is pointing in.

About the inverted sphere: probably the easiest way to do it working 
from an existing sky_sphere definition would be to set it up as a 
unit-radius inverted sphere, texture it, and then scale it to the 
desired size.

sphere {< 0, 0, 0>, 1 inverse
    texture {...}
    scale 10000
}

-- 
Christopher James Huff <cja### [at] gmailcom>
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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