POV-Ray : Newsgroups : povray.general : color_map is "dirty" on a plane that goes thru the origin Server Time
31 Jul 2024 10:28:01 EDT (-0400)
  color_map is "dirty" on a plane that goes thru the origin (Message 1 to 3 of 3)  
From: talk do stop
Subject: color_map is "dirty" on a plane that goes thru the origin
Date: 11 Mar 2007 12:50:00
Message: <web.45f440c8f0c5f335e8e88bca0@news.povray.org>
If I try the following scene, the top of the cylinder will be a noisy
mixture of the two colors in the color_map.

#declare height = 0;
cylinder {
    <0,height,0> <0,-1.2,0> 2
    texture { pigment {
        gradient -y
        color_map {
            [0 color rgb <1,1,0>]
            [1 color rgb <0,0,1>]
        }
        scale <1, 2, 1>
    }}
}
camera { look_at <0,0,0> location 3 }
light_source { 3 color rgb 1}


If however the height is changed to 0.001, the color is fine.  I am not
quite sure if it's a bug, or I just overlooked something, but I wouldn't
expect this behavior.


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From: Thorsten Froehlich
Subject: Re: color_map is "dirty" on a plane that goes thru the origin
Date: 11 Mar 2007 13:08:51
Message: <45f445b3@news.povray.org>
talk.do.stop wrote:
> If I try the following scene, the top of the cylinder will be a noisy
> mixture of the two colors in the color_map.

Same cause: <http://www.povray.org/documentation/view/3.6.1/154/>


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From: Jim Charter
Subject: Re: color_map is "dirty" on a plane that goes thru the origin
Date: 12 Mar 2007 00:56:58
Message: <45f4ebaa$1@news.povray.org>
talk.do.stop wrote:
> If I try the following scene, the top of the cylinder will be a noisy
> mixture of the two colors in the color_map.
> 
> #declare height = 0;
> cylinder {
>     <0,height,0> <0,-1.2,0> 2
>     texture { pigment {
>         gradient -y
>         color_map {
>             [0 color rgb <1,1,0>]
>             [1 color rgb <0,0,1>]
>         }
>         scale <1, 2, 1>
>     }}
> }
> camera { look_at <0,0,0> location 3 }
> light_source { 3 color rgb 1}
> 
> 
> If however the height is changed to 0.001, the color is fine.  I am not
> quite sure if it's a bug, or I just overlooked something, but I wouldn't
> expect this behavior.
> 
> 
> 
The slope wave of the gradient is breaking just at the top of the 
cylinder.  Your workaround it fine or you could also expand the scale of 
the pigment slightly and translate it.


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