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In article <3996F67E.1C9E657B@pobox.com>, Anton Sherwood
<bro### [at] pobox com> wrote:
> What's crackle solid? (I *did* rtfm!)
It makes each "cell" of the crackle pattern a different (solid) color,
and it is documented in the MegaPOV manual, so I suggest you rtfm again.
Specifically, section 8.3.2 "Crackle types". :-)
--
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/
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Chris Huff wrote:
>
>
> How is DNoise() different from Noise()? This is something I have never
> figured out. I had just assumed both had the same problem.
>
As much as I understand, Noise and DNoise should be fairly same
(DNoise's first component has same value as Noise's return value for
same evaluation point), so I think that this fix should be applied there
as well.
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"Vahur Krouverk" <vah### [at] aetecee> wrote...
> Chris Huff wrote:
> >
> >
> > How is DNoise() different from Noise()? This is something I have never
> > figured out. I had just assumed both had the same problem.
> >
> As much as I understand, Noise and DNoise should be fairly same
> (DNoise's first component has same value as Noise's return value for
> same evaluation point), so I think that this fix should be applied there
> as well.
The algorithm that produces the fractal pattern for DNoise and Noise is very
similar. DNoise produces a vector of noise, while Noise produces a single
output.
The algorithm itself basically produces an output in the range of
approximately [-1,1]. This is what DNoise wants for each component, so it
doesn't change anything. However, Noise needs to change it to [0,1] for use
in a pattern. However, in the official conversion, the change is incorrect,
and it over-saturates the top end. MegaPov just fixes the conversion.
The old version simply adds 0.5, while the new version (for all practical
purposes) adds 1 and then divides by two.
-Nathan
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> > What's crackle solid? (I *did* rtfm!)
Chris Huff wrote:
> It makes each "cell" of the crackle pattern a different (solid) color,
> and it is documented in the MegaPOV manual, so I suggest you rtfm again.
Oh: rtwfm; r2fm.
Just started playing with Mega yesterday. When I get my obligatory
Shiny Sphere (containing an iso) the way I want it, I'll put it on a
plane crackle solid rather than checkered.
--
Anton Sherwood -- br0### [at] p0b0xcom -- http://ogre.nu/
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Nathan Kopp wrote:
>
>
> The algorithm that produces the fractal pattern for DNoise and Noise is very
> similar. DNoise produces a vector of noise, while Noise produces a single
> output.
>
> The algorithm itself basically produces an output in the range of
> approximately [-1,1]. This is what DNoise wants for each component, so it
> doesn't change anything. However, Noise needs to change it to [0,1] for use
> in a pattern. However, in the official conversion, the change is incorrect,
> and it over-saturates the top end. MegaPov just fixes the conversion.
>
Ah, so DNoise values are supposed to be between -1 and 1? Indeed, If I
think about it, then in official version its range was not changed
either.
> The old version simply adds 0.5, while the new version (for all practical
> purposes) adds 1 and then divides by two.
By old You mean official version (3.02??) and by new 3.5?
Are those constants, found by Xander and used in MegaPOV, removed in new
version and (+1)/2 used instead?
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"Vahur Krouverk" <vah### [at] aetecee> wrote...
>
> Ah, so DNoise values are supposed to be between -1 and 1? Indeed, If I
> think about it, then in official version its range was not changed
> either.
It was changed, but not correctly.
> By old You mean official version (3.02??) and by new 3.5?
Yes.
> Are those constants, found by Xander and used in MegaPOV, removed in new
> version and (+1)/2 used instead?
Yes. (+1) / 2 will be used. Remember that the constants Xander found were
very close to that and were determined by sampling a thousand or so points.
-Nathan
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