POV-Ray : Newsgroups : povray.general : lighting problem? : Re: lighting problem? Server Time
1 Aug 2024 08:17:43 EDT (-0400)
  Re: lighting problem?  
From: Trevor G Quayle
Date: 23 Jan 2006 21:29:32
Message: <43d5910c$1@news.povray.org>
the problem is in one of your spheres:

//start
sphere {
  0, 1
  translate <10, 10, 10>
  texture {
    pigment {
      gradient y
      color_map {
        [0.0 color rgb 1.0 ]
        [0.3 color rgb <0.6, 0.65, 1.0> ]
      }
    }
    finish { ambient 1 diffuse 0 }
  }
  scale 1000
  hollow on
}

//end

You are misusing translate and scale here, or at least its not operating as 
you expect it to.  When you scale something, it gets scaled based at the 
origin, so translating *then* scaling does not equal scaling *then* 
translating.  In the original, the sphere was placed at <0,0,0> with a 
radius of 1, then scaled 1000x.  Since it was centered at the origin, the 
result is that the sphere remains centered around the origin but now has a 
radius of 1000.   In your example here, you made a 1 radius sphere at the 
origin and translated it <10,10,10> giving you a sphere with its center at 
<10,10,10>. Then you scaled it 1000, which scaled the sphere larger, but 
because scale centers on the origin, the <10,10,10> translation gets scaled 
to a <10,10,10>*1000 translation giving you a 1000 radius sphere at 
<10000,10000,10000> and therefore reflects in your other objects 
differently.  To get the correct results, move the translation after the 
scale:

//start
sphere {
  0, 1
  texture {
    pigment {
      gradient y
      color_map {
        [0.0 color rgb 1.0 ]
        [0.3 color rgb <0.6, 0.65, 1.0> ]
      }
    }
    finish { ambient 1 diffuse 0 }
  }
  scale 1000
  translate <10, 10, 10>
  hollow on
}

//end

Hope this helps you figure out what's going on.

-tgq


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