Christoph Hormann <chr### [at] gmxde> wrote in 
news:3D81CBB1.7BA88E82@gmx.de

> environment mapping certainly isn't
> one of them.

You realy do not like env-maps, do You ;) ?


-- 
#macro g(U,V)(.4*abs(sin(9*sqrt(pow(x-U,2)+pow(y-V,2))))*pow(1-min(1,(sqrt(
pow(x-U,2)+pow(y-V,2))*.3)),2)+.9)#end#macro p(c)#if(c>1)#local l=mod(c,100
);g(2*div(l,10)-8,2*mod(l,10)-8)*p(div(c,100))#else 1#end#end light_source{
y 2}sphere{z*20 9pigment{function{p(26252423)*p(36455644)*p(66656463)}}}//M

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Rafal 'Raf256' Maj wrote:

> Christoph Hormann <chr### [at] gmxde> wrote in
> news:3D81CBB1.7BA88E82@gmx.de
> 
>> environment mapping certainly isn't
>> one of them.
> 
> You realy do not like env-maps, do You ;) ?

  Me neither, specially if I've a more realistic and useful way to simulate 
reflections. Not to say much more easy to use. And I don't care if it is 
slower to render (for that purpouse there already exist scanline rendering 
engines).

-- 
Jaime Vives Piqueres

La Persistencia de la Ignorancia
http://www.ignorancia.org

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Ken wrote:
> 
> As far as I know there are no plans [by the POV-Team] for a version 3.6
> and no plans to change those plans. People are going to have to put up
> with unofficial patches until POV-Ray v4.0 comes out.
> 

 Well, the new "megapov" can take the role of the missing 3.6, if some of 
the known techies can glue all the future patchs togheter. I've no doubt 
that such new "superpatch" (or whatever you like to call it), will be made, 
but surely not before some (few?) months. And most of us will be using it 
until v4.0, as we have done with the old megapov until 3.5 was released. 

-- 
Jaime Vives Piqueres

La Persistencia de la Ignorancia
http://www.ignorancia.org

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>That wasn't my question, it was whether you have actually tried to use
>them for whatever purpose you want a HDR-Image for.

Not directly in povray. I toyed with a GI extension to a raytracer I wrote
with some friends (truetrace it was called, written *many* moons ago, dead
when I changed job) and, using a 16-bit integer color image as a source for
illumination and environment, I ran into troubles with outdoor scenery.
I was trying to immerse a somewhat reflective object in an actual ambient (a
fisheye photograph, taken outdoors on sunny day) and I could't get the
dynamic range right, due to the sun. Then I fished an old copy of Radiance
and took out the code for fp images. I ended using an ad-hoc solution,
using a shared exponent for three mantissas (1 normalized and 2
denormalized) which worked quite well. The discussion about a floating
point rep for color components reminded me of the thing and, trying to
recover the algorithms for fp colors, I stumbled on SGI's LogLuv color
encoding
(http://positron.cs.berkeley.edu/~gwlarson/pixformat/tiffluv.html), which
is far better.

>While HDR-Images can of course be used as environment maps this won't make
>environment mapping any more useful in a raytracer.  HDR-Images are
>certainly useful for various purposes in POV-Ray and there already is a
>patch supplying support for that, but environment mapping certainly isn't
>one of them.

Why not?
I mean why environment mapping wouldn't be useful?

I suspect that we didn't properly understand each other (surely my fault,
I'm browsing the newsgroups while I'm working and COBOL do things to your
brains after a while).

What you intend for environment mapping?

Alex

P.S.: *sigh* - COBOL...what a shame for me...

Can you imagine writing a ray-tracer in COBOL?
I mean, COBOL is Turing-equivalent, is it?

Heh, it wouldn't be too fast, but at least it would be accurate in
calculating expenses and taxes (provided your scene doesn't cross a century
while rendering :-)

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ABX wrote:
>In case you missed this I'm making my patches this way.

*I* had missed it....

Congratulations, it is an outstanding work.

Can I partecipate?

How do I submit patches? There are guidelines, policies, style guides?

Alex

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In article <Xns### [at] 204213191226>,
 "Rafal 'Raf256' Maj" <raf### [at] raf256com> wrote:

> > environment mapping certainly isn't
> > one of them.
> 
> You realy do not like env-maps, do You ;) ?

I dislike them strongly, they only make sense for applications where 
real reflections are impossible. POV doesn't need them.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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On Fri, 13 Sep 2002 09:21:23 EDT, "Alex" <ale### [at] alphacit> wrote:
> ABX wrote:
> > In case you missed this I'm making my patches this way.
>
> *I* had missed it....
> Congratulations, it is an outstanding work.

Thanks.

> Can I partecipate?

Sure. It is only one month old but I have already met one person who refused
to be included in my repository.

> How do I submit patches? There are guidelines, policies, style guides?

There are no guidelines. Describe necessary changes in favourite form (be sure
it is reradable and understable) and post it to povray.programming,
povray.unofficial.patches or upload it somewhere in the net and warn community
about it. I will probably catch it but for sure you can warn me personally to
add to database of available patches. I don't include patches on my site
(except my own). I only link to them.

ABX

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In article <web.3d8193ecfeedefd415e7f0160@news.povray.org>,
 "Alex" <ale### [at] alphacit> wrote:

> If I might dare offer such an example, I'd say that
> env. mapping and a floating point file format (though not one
> as simple as the one envisioned by Mr. Maj: point your google to
> shared exponent floating point) could help implementing HDRI in POV.

The words "RGBE" and "Radiance" would help in that search. I've been 
working on some code for reading/writing these files, if I get it 
working I'll patch it into POV or post it to these newsgroups for 
someone else to put into POV. Don't let this discourage anyone else from 
doing it though...that project is on hold for a while, and it isn't even 
a POV patch yet.


> Now, don't tell me HDRI is a hack: the whole ray-tracing stuff is a hack.

HDRI: High Dynamic Range Image? Actually I'd say that the limited range 
image formats are hacks. ;-)


> And, beside that, using denormalized mantissas for color components
> is very useful for postprocessing (and far better than 16-bit output).

The post-processing patch had a "filter" that restored the non-clipped 
values to the image. Everything was taken care of in POV, without going 
to a file, so you had to write a filter or use existing ones, but 
filters were very easy to write. This also let you keep full float 
precision, without even the loss of precision from RGBE format, and let 
you control filters using POV Script and features like pigments and 
patterns. It'd probably work best if POV could save the necessary data 
and run just the post-process stuff without re-rendering the scene, 
though.


> I surely can grok the whole thing by myself, alone, in a week, perhaps,
> coming to grasp every little nuance of the source code (yes, I have that
> experience in programming), but *I* *don't* *have* *time*. I want to see the
> POV-Ray community grow,

In a week? If you didn't have to sleep and already knew all the 
algorithms used. However, getting a basic understanding of the code and 
of where and how to modify it to add a specific feature shouldn't take 
any longer than that for a good coder.


> I love it, I want to see the bleeding edge of CG research in POV-Ray.
> But. But, I don't have time to contribute much: so I would love to buy
> a book about POV-Ray programming, to have a CVS of an experimental POV-Ray.
> *sigh*. Vox clamavit in deserto.

The POV Team has talked about a more open development model for 4.0, so 
it is a possibility...

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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In article <3D819B95.D48BD5A9@gmx.de>,
 Christoph Hormann <chr### [at] gmxde> wrote:

> Have you actually ever tried using the 48 bit color output generated by
> POV-Ray?

That's still in a 0-1 range, which limits some things quite a bit.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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>In a week? If you didn't have to sleep and already knew all the
>algorithms used. However, getting a basic understanding of the code and
>of where and how to modify it to add a specific feature shouldn't take
>any longer than that for a good coder.
It's simple.
Work on a patch for a booking system written in Java by a bunch of former
code grinders, add a hard deadline (bank executive board meeting) and
you'll develop an astounding agility in walking the sources. Heck, z80
assembler makes clearer code to read. 14000 lines in a file and one comment
in it:
// Following code deprecated
if(0) {

}
Ack!


>
>The POV Team has talked about a more open development model for 4.0, so
>it is a possibility...
>

Development model sounds fine, IMHO. Each POV release was far more polished
than most commercial rendering packages (realistic deadlines *do* help).
I think ABX is doing a great thing: his patches are well commented and
useful both for the advanced geek and the beginner. Maybe we could build on
this and put a patch repository.
I would be glad to offer a site to host this.

Alex

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