"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-66E8D2.10304829062000@news.povray.org...

> Well, the problem with the old noise3d() and bozo was that it was that
> the plateaus were limiting their usefulness in isosurfaces, height
> fields, normals, etc.

> "bumps" isn't standard, but this type of noise is a commonly used
> feature.
> However, it isn't a standard. As far as I know, the only requirement is
> that it is a pseudo-random smoothly changing function which is
> relatively uniform at large scales.

Known and agreed, but I would not say that it was useless. Any great images
were created with the good'ol "faulty" bumps. And many people are used to
use it, and know how to code a map which will give them the result they are
looking for. (And I am still not writing of backward compatibility - oops, I
just did.) SO, please, keep them near at hand (and, no, I do not like using
#version in the middle of a scene).


> Just extend the colors at each end of the color_map(compressing the
> other values toward the center), so there is an area of flat color at
> each end, and you will end up with plateaus just like the official
> version's. Making it more like Jerome's would be a bit more work, but I
> think it could be done easily as a waveform or isosurface function.

So, could we use a #macro mapOldBump(mapValue) that could use the exactly
correct function to switch to different bumps' incarnation. Can anyone with
access to source do this?


> > My own <repetition> I still think that Pov could use some syntax
> > rewritings </repetition>.
>
> You are not alone...I would prefer a completely different way of
> layering textures, and a slightly different syntax for
> patterns...#for(;;) loops, #set, etc would also be nice.

One of the many problem being that everybody has its preferences. We need
pov-team benevolent and knowledgeable dictatorship.

Povingly,


Philippe

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On Fri, 30 Jun 2000 02:43:32 -0400, "Mark Wagner"
<mar### [at] gtenet> wrote:

>>noise3d is commonly reffered to as "perlin noise". You can find a good
>>description of it at Hugo's site -
>
>noise3d is actually a single octave of perlin noise.  True perlin noise is
>the sum of several sets of differently-scaled noise3d.

Like the granite pattern?


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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In article <64qpls4m889imjg9002mr03jar85id340o@4ax.com>, Peter Popov 
<pet### [at] usanet> wrote:

> Like the granite pattern?

Or the wrinkles pattern, or turbulence.

-- 
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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In article <395cb293$1@news.povray.org>, "Philippe Debar" 
<phi### [at] hotmailcom> wrote:

> Known and agreed, but I would not say that it was useless.

I didn't say it was useless, just that it was limited by the plateus. I 
ran into them several times, and either abandoned the scene or wasted 
time looking for some way to work around it.


> So, could we use a #macro mapOldBump(mapValue) that could use the 
> exactly correct function to switch to different bumps' incarnation. 
> Can anyone with access to source do this?

Yes, you could probably make a macro to correct the blend map values, 
then all you would have to do is duplicate the end ones...or you could 
use the function pattern and reproduce the older version or both new 
versions without even touching the blend map.

-- 
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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Philippe Debar wrote in message <395cb293$1@news.povray.org>...
>So, could we use a #macro mapOldBump(mapValue) that could use the exactly
>correct function to switch to different bumps' incarnation. Can anyone with
>access to source do this?


The procedure for converting a blend map:
Divide each value by 2 and add 0.25

Mark

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"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-97A564.17491930062000@news.povray.org...
> I didn't say it was useless, just that it was limited by the plateus. I
> ran into them several times, and either abandoned the scene or wasted
> time looking for some way to work around it.

I am awfully sorry. I never wanted to put words in your mouth.

I must say I was surprised to find my post a bit harsh when I re-read it
today. I wasn't my intention at all.

All in all, what I wanted to say is that I was a little disappointed that
the old bumps was accessible only through #version, because I thought that
it still has uses in current megapov (future pov?) versions. But as it seems
it is easy to make it work in povscript , all is well.


> Yes, you could probably make a macro to correct the blend map values,
> then all you would have to do is duplicate the end ones...or you could
> use the function pattern and reproduce the older version or both new
> versions without even touching the blend map.

Great. I suppose the corrected-map solution would be the quickest
(render-time-wise). For the function pattern, I suppose you mean wrapping an
"adapter" function around the noise/bumps.

Just for interest's sake: is it possible to re-write the old noise/bumps
function from scratch in povscript? Isn't the noise function iterative? Is
it possible to write iterative functions for the function pattern or
isosurface?


Thank you for your explanations (I _like_ the TAG team),


Povingly,


Philippe

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"Mark Wagner" <mar### [at] gtenet> wrote in message
news:395ee45a@news.povray.org...
> The procedure for converting a blend map:
> Divide each value by 2 and add 0.25


Thank you very much, Mark.


Philippe

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In article <39609879@news.povray.org>, "Philippe Debar" 
<phi### [at] hotmailcom> wrote:

> Great. I suppose the corrected-map solution would be the quickest 
> (render-time-wise). For the function pattern, I suppose you mean 
> wrapping an "adapter" function around the noise/bumps.

I'm not sure what you mean...I meant something like this:

#declare oldBozo = function {max(0, min(1, noise3d(x,y,z)*1.5 - 0.25))}

This should be pretty close to the original bozo, though I was just 
guessing at the range(this one goes from -0.25 to 1.25 before clipping 
to create the plateaus, I don't know how far the original went). And it 
should also be quite fast...I rarely notice any speed difference with 
functions this simple.


> Just for interest's sake: is it possible to re-write the old noise/bumps
> function from scratch in povscript? Isn't the noise function iterative? 
> Is it possible to write iterative functions for the function pattern 
> or isosurface?

You could...but it would be a huge pain and would parse slowly. This was 
why I added noise3d() for use outside isosurfaces, and the eval_*() 
functions. And I wouldn't be able to, I don't know anything about noise 
and hash functions except for what they do.
BTW, what do you mean by "iterative function"? Do you mean recursive or 
looping?

-- 
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:
> BTW, what do you mean by "iterative function"? Do you mean recursive or
> looping?

An iterative function is a function that uses a previous result
of itself at each step : 

Any fractal function is iterative.

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Hi again!

"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-DB8295.09271003072000@news.povray.org...
> I'm not sure what you mean...I meant something like this:
>
> #declare oldBozo = function {max(0, min(1, noise3d(x,y,z)*1.5 - 0.25))}

That's exactly what I meant... I guess I am too lazy - and maybe I like to
much being cryptic ;-)



<snip>
> BTW, what do you mean by "iterative function"? Do you mean recursive or
> looping?


Yes that's what I was trying to say. You are getting very good at reading
minds... now, let's do telekinesis :-)



Povingly,


Philippe

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