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There seems to be a bug in the various noise functions. It exhibits itself as
banding after a certain _negative_ distance, along any axis, from the origin.
This distance varies depending on the noise function: it is around 78.125 for
1/f noise (granite), 312.5 (78.125*4) for DNoise and Agate noise, and around
10000 for Perlin noise (bozo, bumps, spotted).
Furthermore, in 1/f and DNoise the bug seems to become more pronounced at
78.125*2 and 78.125*4
Versions: POVWin 3.1g (Watcom and VC compile), POV Superpatch (3.1e codebase).
The problem was also reported to exist on 3.01r1.watcom
System: Celeron, 128MB RAM, Win98
//BEGIN EXAMPLE SCENE
camera{
orthographic
location y*5
up y*5*.75 right x*5
look_at 0
}
//1/f noise (granite)
#declare Tex1=
pigment{
granite
color_map{[0 rgb 0][1 rgb 1]}
translate 78.13*x //First signs of banding
//translate 156.25*x //More pronounced
//translate 312.5*x //Even more pronounced
scale 5
}
//Perlin noise (Bozo & Bumps & Spotted)
#declare Tex2=
pigment{
bozo
color_map{[0 rgb 0][1 rgb 1]}
translate 10000*x
scale 1
}
//DNoise (turbulence)
#declare Tex3=
pigment{
gradient x
color_map{[0 rgb 0][1 rgb 1]}
translate 312.5*x //Banding starts
//translate 625*x //Becomes more pronounced
scale 1
turbulence 1
}
//Agate turbulence
#declare Tex4=
pigment{
agate
color_map{[0 rgb 0][1 rgb 1]}
translate 312.5*x //Banding starts
scale 5
}
plane{
y,0
pigment{Tex1}
finish{ambient 1}
}
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