In p.u.p,  we were discussing options for getting a plateau-free noise
function for pov.  I was experimenting with the pattern-based pigments
in isosurfaces and wonder if I found something in dents.

The "dents" pattern below almost looks plateau-free, although not
exaclty "smooth" as the ideal function I'm looking for would have.
"Bumps" has plateaus.  So how are dents and bumps different?

 [This same text and actual images in p.b.i].

//           switch to                         DENTS here
#declare yikes=function{pigment {bumps scale 30}}
#declare funk=
isosurface{
        function{
              y/100+yikes(x,y,z)/2}
              sign 1
              accuracy 0.01
              threshold 1
           clipped_by
           { sphere{0,250}}
        }

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In article <389e0905@news.povray.org>, "Greg M. Johnson" 
<"gregj;-)56590"@aol.c;-)om> wrote:

> The "dents" pattern below almost looks plateau-free, although not
> exaclty "smooth" as the ideal function I'm looking for would have.
> "Bumps" has plateaus.  So how are dents and bumps different?

While bozo, spotted, and bumps simply call Noise(), the function for 
dents seems to just return the cube of Noise().(I really don't see how 
this could be useful when poly_wave and bozo(or bumps, or spotted) could 
give the same result...I assume it comes from a version which didn't 
have pattern waveforms yet)
Probably the reason it appears to not have any plateaus is the way it 
curves near the edge of the plateau. The action of cubing the value 
might make it curve so the flat area is almost indistinguishable.

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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Chris Huff wrote:


> (I really don't see how this could be useful when poly_wave and bozo
>(or bumps, or spotted) could give the same result...I assume it comes
> from a version which didn't have pattern waveforms yet)

The only normal patterns and modifiers that were available in POV-Ray v2.2
are as follows -

        5.4.2   NORMAL
                5.4.2.1 Bumps
                5.4.2.2 Dents
                5.4.2.3 Ripples
                5.4.2.4 Waves
                5.4.2.5 Wrinkles
                5.4.2.6 Bump_map
                        5.4.2.6.1   Specifying a bump map.
                        5.4.2.6.2   Bump_size
                        5.4.2.6.3   Use_index & use_color
                        5.4.2.6.4   The "once" option.
                        5.4.2.6.5   The "map_type" option.
                        5.4.2.6.6   The "interpolate" option.
                5.4.2.7 Normal Modifiers
                        5.4.2.7.1   Turbulence
                        5.4.2.7.2   Frequency and Phase
                        5.4.2.7.3   Transforming normals


-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Ah yes, the cube! It's so obvious now in comparing the two objects........

Chris Huff wrote:

> In article <389e0905@news.povray.org>, "Greg M. Johnson"
> <"gregj;-)56590"@aol.c;-)om> wrote:
>
> > The "dents" pattern below almost looks plateau-free, although not
> > exaclty "smooth" as the ideal function I'm looking for would have.
> > "Bumps" has plateaus.  So how are dents and bumps different?
>
> Probably the reason it appears to not have any plateaus is the way it
> curves near the edge of the plateau. The action of cubing the value
> might make it curve so the flat area is almost indistinguishable.
>
> --
> Chris Huff
> e-mail: chr### [at] yahoocom
> Web page: http://chrishuff.dhs.org/

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