There is one problem with pov-ray for me. I seem to be stuck on this problem
i tried solving it and i couldn't. When you declare colors in rgb <1,0,0> }
inside the brackets. How do i find a color using this statement or other
colors. I want to create a background from light blue to dark blue, the sky.
It just dosen't seem to work  Also is there a way of finding out which color
is which when you use the rgb statement above.

Thanks in advance :-)

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"maheshtd" <mah### [at] onetelnetuk> wrote in message
news:3cf89b4f@news.povray.org...
> There is one problem with pov-ray for me. I seem to be stuck on this
problem
> i tried solving it and i couldn't. When you declare colors in rgb
<1,0,0> }
> inside the brackets. How do i find a color using this statement or other
> colors. I want to create a background from light blue to dark blue, the
sky.
> It just dosen't seem to work  Also is there a way of finding out which
color
> is which when you use the rgb statement above.

Basically, no. Only if a database were created first and the values matched
names in the database (array? file?).

Colors are created in the following way:

rgb <0,1,1> is cyan or a light blue. rgb <0,0,1> would be medium blue, and
rgb <0,0,0.5> might be called a dark blue. That's only my idea of those
though, you could get color numbers from a web style color coding and
convert to RGB since those often have names for them.

Also, if you want to get the values later on in a scene file you can do this
(I realize though that you might not be interested in this kind of thing):

#declare LtBlu=<0,1,1>;

Then like:

pigment {color rgb LtBlu.z} // only the blue
pigment {color rgb LtBlu.y+LtBlu.z} // both green and blue (light blue)

Or like:

#declare PartBlue=LtBlu.z

Maybe you understand what I'm saying, those are dot operators so you can
look up those words in the docs and find out more.

Back to what you were actually asking about the shaded coloration for sky...
You need a "blend" map, which is done in the following way:

sky_sphere {
pigment {
    gradient y // pattern going up and down
        color_map { // the blending colors below
            [0 color rgb <0,1,1>] // lighter horizon
            [1 color rgb <0,0,1>] // darker zenith
            }
// this makes a horizon line which is also the dark color below y*0
// to make it another way you need to add scale translate or a wave form.
        }
}

Those colors can be anything, of course. For instance, <0.4,0.8,1.0> and
<0.3,0.6,0.9>.

For color names with RGB values have a look at
http://sed.ucsd.edu/escowles/rgb.html
There are many such places to be found on the web. Main idea is to use the 0
to 255 decimal value for each x, y, z of the rgb vector (<r,g,b>) and divide
by 255 to get 0 to 1 that POV interpretes as the color. Example: color rgb
<0,191,255>/255 is deep sky blue as on that web page.

bob h

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bob h wrote:

> For color names with RGB values have a look at
> http://sed.ucsd.edu/escowles/rgb.html
> There are many such places to be found on the web. Main idea is to use the 0
> to 255 decimal value for each x, y, z of the rgb vector (<r,g,b>) and divide
> by 255 to get 0 to 1 that POV interpretes as the color. Example: color rgb
> <0,191,255>/255 is deep sky blue as on that web page.

Or save yourself the time and trouble by using the two .inc color include
files available from my site -

http://home.pacbell.net/tylereng/index.html

-- 
Ken Tyler

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maheshtd wrote:

> There is one problem with pov-ray for me. I seem to be stuck on this problem
> i tried solving it and i couldn't. When you declare colors in rgb <1,0,0> }
> inside the brackets. How do i find a color using this statement or other
> colors. I want to create a background from light blue to dark blue, the sky.
> It just dosen't seem to work  Also is there a way of finding out which color
> is which when you use the rgb statement above.


Get yourself a color mixing utility, like Jamis Buck's ColorPicker.

http://www.geocities.com/jamisbuck/downloads.html


With that, you can mix your colour from rgb or hsl, or pick it from a 
palette. It will even give you a color statement i pov syntax, ready to 
cut'n'paste into your scene file.

/Ib

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I use Pick'o'color by Andreas Gerdes.  I has a cool feature that allows you
to pick a colour from the screen, i.e., from a picture.  I can't find a link
that works anymore, but if there is any interest in it, I can post it.

-tgq

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"bob h" <omn### [at] charternet> wrote in message
news:3cf8c550@news.povray.org...
I need to point out that I didn't use proper color-getting dot operators
there, from lack of usage of them myself. Using the extracted values is
probably not what you're after anyhow.
Instead they'd be .red, .green and .blue since those others are really meant
for getting xyz vector values and not colors.
I should also note here that reusing these can be confusing unless you
realize they involve a 5D vector, <r,g,b,f,t>. More about it can be found in
the doc under operators. But frankly, I didn't make a working example before
anyhow, the addition of .y+.z or even .green+.blue makes <2,2,2,2,2>. Which
goes to show how little I use those. I thought they made a vector of
<0,1,1,0,0> again! Either that or somethings wrong with POV-Ray in that
regard. When in doubt suspect yourself first I guess. I'll have to check
into this further.

bob h

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Wasn't it maheshtd who wrote:
>There is one problem with pov-ray for me. I seem to be stuck on this problem
>i tried solving it and i couldn't. When you declare colors in rgb <1,0,0> }
>inside the brackets. How do i find a color using this statement or other
>colors. I want to create a background from light blue to dark blue, the sky.
>It just dosen't seem to work  Also is there a way of finding out which color
>is which when you use the rgb statement above.

Most programs that have a colour picker will display the R G B values of
the colour you are picking. (Sometimes you'll have to click on "define
custom colour"). The values that get displayed will be in the range 0 to
255, so just divide each of the values by 255.

E.g. if the colour picker says "Red 143, Green 204, Blue 237" then in
POVRay you get that colour from {rgb <143/255, 204/255, 237/255>}.

-- 
Mike Williams
Gentleman of Leisure

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