POV-Ray : Newsgroups : povray.bugreports : Spotted normal bug (Jerome M. Berger) Server Time
23 Dec 2024 03:54:30 EST (-0500)
  Spotted normal bug (Jerome M. Berger) (Message 1 to 2 of 2)  
From: Peter Popov
Subject: Spotted normal bug (Jerome M. Berger)
Date: 22 Nov 1999 20:40:23
Message: <3839f087@news.povray.org>
/*
This file shows a bug in the spotted pattern. The bug manifests in 
a visible square grid in the spotted pattern. It is also visible 
in the bozo pattern.

The bumps normal does not show such a problem.

The bug does not show up when the patterns bozo, spotted and bumps 
are used as pigments

Reference:

Message-ID: <38323B08.E75DD458@enst.fr>
Date: Tue, 16 Nov 1999 21:20:08 -0800
From: "Jerome M. BERGER" <jbe### [at] enstfr>
Newsgroups: povray.binaries.images

This bug has been verified by myself. System details follow:

CPU: AuthenticAMD AMD-K6tm w/ multimedia extensions, clock 193 MHz
RAM: 96 MB
OS : Microsoft Windows 98 4.10.1998 
POV: Version 3.1g.watcom.win32 [Pentium II Optimised]

Peter Popov
pet### [at] usanet
*/

union
{
  sphere { y+x, 1 }
  box { -1, 1 translate y-x }
  texture
  {
    pigment { color rgb 1 }
    finish { phong 1 }
    normal { spotted 0.5 scale 1 }
  } 
}

light_source { <500,0,-100> color rgb 1 }
light_source { <0,500,-100> color rgb 1 }

camera
{
  location  <0.0 , 0.0 ,-2.25>
  up y
  right x
  look_at   <0.0 , 0.0 , 0.0>
  orthographic
}

Peter Popov
ICQ: 15002700


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From: Nathan Kopp
Subject: Re: Spotted normal bug (Jerome M. Berger)
Date: 23 Nov 1999 14:44:22
Message: <383aee96@news.povray.org>
Peter Popov <pet### [at] usanet> wrote...
> /*
> This file shows a bug in the spotted pattern. The bug manifests in
> a visible square grid in the spotted pattern. It is also visible
> in the bozo pattern.
>
> The bumps normal does not show such a problem.
>
> The bug does not show up when the patterns bozo, spotted and bumps
> are used as pigments
>

Actually, the bozo/spotted pattern _does_ show this bug when used as a
pigment (it is just very subtle).  Below is a scene (modified from the one
provided by Peter), that puts the bozo bumps on a plane.  It will also
create contour lines in the pigment.  If you look closely, you can see how
the contour lines in the pigment match the grid-like pattern.

Therefore, this is most likely a bug in the bozo pattern itself, and is
probably related to what Xander posted a week or so ago.

-Nathan

// begin POV scene
plane{
  z,0
  texture
  {
  #declare pig=yes;
  #if (pig)
    pigment { bozo color_map{
                     // s is delta for the contour lines
                     #declare s=.05
                     #declare a=0;
                     #while(a<=1)
                       [a rgb 1]
                       [a+s/4 rgb 1]
                       [a+s/4 rgb .5]
                       [a+s/4*2 rgb .5]
                       [a+s/4*2 rgb 1]
                       #declare a=a+s;
                     #end
                     }
               scale 1}
    finish { specular 1 }
  #else
    pigment { color rgb 1 }
    finish { specular 1 }
  #end
    normal { bozo 0.5*5
             slope_map{[0 <0,0>][1 <1,0>]}
             scale 1 }
  }
}

light_source { <500,0,-100> color rgb 1 }
// light_source { <0,500,-100> color rgb 1 }

camera
{
  location  <0.0 , 0.0 ,-2.25>*2
  up y
  right x
  look_at   <0.0 , 0.0 , 0.0>
  orthographic
}


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