Claude Mench <c.m### [at] adilinstrumentscom> wrote:
:> With photon mapping lots of photons will be shot in vain; they will just
:> end somewhere in the scene where they do not affect anything.

: I'm not sure to understand you, in photon mapping photons are not
: shoot anywhere, they are shot only in a direction of an object, never
: in a direction where is nothing.

  Suppose that the object is hidden behind other objects and in such position
that it doesn't affect the illumination of other objects.
  Photon mapping would calculate the illumination of _every_ surface, even
if that surface is not visible nor it participates in the illumination of
the scene. If a surface is partially hidden, photon mapping will calculate
the illumination of the whole surface although it wouldn't be necessary.
  Stochastic raytracing only calculates the illumination of visible
surfaces and those surfaces that participate in the illumination. Even with
partially visible surfaces it only calculates radiosity for the visible parts
and leaves the hidden parts alone (unless this hidden part reflects light
to another visible surface).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Nieminen Juha wrote:
> 
> Claude Mench <c.m### [at] adilinstrumentscom> wrote:
>...
> :         - Can we expect an preview mode using OpenGL (I'm
> :           aware that the tessalation of all objects existing
> :           in pov will be difficult, and infinity ojects also...)
> 
>   You answered your own question. Converting all the primitives to
> triangles is not a trivial task and probably not worth the efforts.
>   And even when OpenGL is a standard, it's not part of the ANSI C++ standard.
> Adding support for it would make povray platform-dependant.

What a bizzare answer.  The OpenGL API doesn't have anything to do with
the ANSI C++ standard.  If you want to call OpenGL functions from your
C++ code, you will find it quite easy to do.  Also, as far as being
cross platform, if you don't have drivers provided with your system you
can always use Mesa (yes, even on Macs, DOS, ...).

As far as tesselating all prims, it may be tedious but certainly not
impossible.  Other renderers manage to do it.  Given the number of times
this question comes up, it is certainly worth consideration. 
Personally, I think the preview thing belongs in a modeller rather than
a back-end renderer like POV-Ray, but it's not out of the question.

Xander

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I'm happy to see finally someone from the pov-team here.
It seems that asking what features could be in POV4.0 or even
only the direction in wich POV goes toward is not a question
that can get an answer...

>As far as tesselating all prims, it may be tedious but certainly not
>impossible.  Other renderers manage to do it.  Given the number of
>times this question comes up, it is certainly worth consideration.

    You where the maker of polyray, which had a Z-Buffer renderer,
so I think you have a good knowledge of this item. In polyray
this code exist for quite a number of primitives, because if I
remember well polyray had many primitives.

>Personally, I think the preview thing belongs in a modeller rather
>than a back-end renderer like POV-Ray, but it's not out of the question.

    I do not see Povray as only a back-end renderer, as I think
in the PC or Mac version much people use the editor and periodicly
during the scene editing do test renders.

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>> And even when OpenGL is a standard, it's not part of the 
>> ANSI C++ standard.  Adding support for it would make 
>> povray platform-dependant.
> 
> What a bizzare answer.  The OpenGL API doesn't have anything 
> to do with the ANSI C++ standard.  

	Go easy on Ken.  He might not be familiar with OpenGL,
	he might not even be a programmer, but he is quite a
	enthusiastic and productive POV-ray kind of a guy,
	and very helpful to have around.

	OpenGL is a well-established standard, and given that
	Microsoft have spent 4 years trying to kill it, it
	is here to stay.  It is safe to regard OpenGL as about
	as portable a realtime 3D rendering API as you're 
	going to get.  Microsoft failed in their attempt to
	"invent 3D graphics" in the way they are seen to have
	invented graphical user interfaces.  OpenGL means
	that you can write modelling software that will work
	across different platforms.  Microsoft doesn't like 
	it of course - look at the way they perverted Java.

	I think that the "front-end" GUI could use a rethink
	in terms of making better use of the quality settings
	and user interface to refine the scene.  I find that
	the current setup is more convenient than the command
	line, but well short of what's possible.  For example,
	I'd like to have common options available as drop-down
	lists on the toolbar, so I can switch resolution and
	quality without having to nagivate the whole list of
	canned combinations.  Also, I'd like to select an area
	of the viewport to be recalculated at better quality and/or
	resolution.  I particularly dislike having to edit the INI
	file, to customise my setting for possibly only one
	render.

	And, (while I'm being wishful) I'd like to have a history
	so that I can check for side effects, or simply reflect
	on whether the image is progressing the way I'd imagined
	it should.

	These ideas do not involve huge amounts of development,
	maintenance, or bug-fixing.  They are simply making
	better use of the current infrastructure.

	It's not the tesselation of primitive that is the
	challenge for OpenGL rendering, it's the CSG and
	flexibility of POV texturing that would be a big
	challenge to achieve.  I've worked for 4 years 
	commercially on a solid modelling engine, and there
	is no way that I'd tackle one as a hobby.  :-)
	Raytracing is not polygon-oriented, and trying to
	have the best of both severely complicates things.
	If someone decides that "super-quartic-hemispherical-
	hybrid-nurbs-bezier-patches" make a very useful modelling
	primitive, they would also have to ponder the implications
	of having to tesselate it, and worry about the volumetric
	represetation.
	
> Personally, I think the preview thing belongs in a modeller rather than
> a back-end renderer like POV-Ray, but it's not out of the question.

	Xander, keep in mind that the POV-ray "mentality"
	is intentionally different to modellers or 
	beasts like 3D Studio.  I have the distinct
	impression that the POV team intentionally target
	a very specific scope of functionality in order
	to keep the software reasonably small and keeping
	the team small, friendly and familiar.  Compare
	POV-ray development to say, KDE or Gnome.  KDE is
	an exciting development effort, but very chaotic.
	I think that in the long term, POV-ray will be
	overtaken by a larger-scale, more open development
	model - but I doubt that the POV team will be too
	upset - they are not trying to kill microsoft, or
	become the next media darling, or foster a huge
	following of novice users.  
	
	But then, I really don't know much - treat this
	as pure speculation.  

	And, as a final thought - it is much easier to 
	toss ideas around as being desirable, feasible,
	or the way to go, but something else entirely
	to do the work yourself, or convince someone 
	on the POV team of your dream.  Everyone wants
	to dream their own dream, and that's especially
	how it should be if people arn't getting paid.

	I mean this from both sides of the coin - 
	people like you and me that say "hey, I know something
	about software/graphics/whatever, and POV really
	lacks xyz...." and others that react against
	"changing the paradigm for no good reason".
	POV is free in the "free beer" sense, but not
	in the "hey guys, do this" sense.  It's their
	baby, and they prefer to pleasently surprise us
	from time to time. 

--
Nigel Stewart (nig### [at] nigelscom)
Research Student, Software Developer, Tokyo Dweller
"The Australian Government wants to read your email."

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On Wed, 08 Dec 1999 01:38:01 +0900, Nigel Stewart wrote:
>	Go easy on Ken.  He might not be familiar with OpenGL,
>	he might not even be a programmer, but he is quite a
>	enthusiastic and productive POV-ray kind of a guy,
>	and very helpful to have around.

Xander's reply was to Warp, not Ken.  To reply to Warp in my own
way, I'd say that my impression is that while the POV-Team strives
for portability, there are some features that aren't and can't be
portable.  If ANSI-standard C was the only rule by which things got
added, there would be no preview display, or Mac GUI, or Windows
GUI, or DOS help screens, or x-povray, or...  you get the idea.  
OpenGL seems fairly widespread, so I would say that if an OGL 
preview deserves to be shot down it deserves to be shot down on its 
own merits as a feature rather than because OGL isn't available on 
the DOS or Amiga platforms.  That's just my opinion, though; I may
be in the minority.

>	And, as a final thought - it is much easier to 
>	toss ideas around as being desirable, feasible,
>	or the way to go, but something else entirely
>	to do the work yourself, or convince someone 
>	on the POV team of your dream.  

Um... Xander is on the POV-Team, and is also the author of Polyray,
which does successfully tesselate lots of different objects.  If he
decided to do so, he could probably do most of the necessary code 
for tesselation in his sleep.  

FWIW, I think tesselation of primitives would be a fairly useful 
feature, too, and not just for OGL preview.  I still think the OGL 
preview wouldn't be much faster than current preview methods, given
the parse time, but I see lots of other uses for being able to make
triangles out of primitives.

-- 
These are my opinions.  I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html

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Ron Parker wrote:

> On Wed, 08 Dec 1999 01:38:01 +0900, Nigel Stewart wrote:
> >       Go easy on Ken.  He might not be familiar with OpenGL,
> >       he might not even be a programmer, but he is quite a
> >       enthusiastic and productive POV-ray kind of a guy,
> >       and very helpful to have around.

Thanks for the support anyway :)

> ... but I see lots of other uses for being able to make triangles
> out of primitives.

Displacement mapping comes to mind...

-- 
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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In article <chrishuff_99-9C557C.20515406121999@news.povray.org> , Chris Huff
<chr### [at] yahoocom>  wrote:

> It is available on the Mac, although I think it requires an accelerator
> card(there isn't even a way to emulate a card, as far as I know).
> I would hate to have POV require a 3D accelerator card, and get no
> benefit from having one other than a preview mode.

No, it should run without an accelerator :-)


     Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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On Tue, 07 Dec 1999 09:21:41 -0800, Ken <tyl### [at] pacbellnet> wrote:

>> ... but I see lots of other uses for being able to make triangles
>> out of primitives.
>
>Displacement mapping comes to mind...

...and virtual light sources, global ilumination maps, morphing, UV
mapping...


Peter Popov
pet### [at] usanet
ICQ: 15002700

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Peter Popov wrote:
> 
> On Tue, 07 Dec 1999 09:21:41 -0800, Ken <tyl### [at] pacbellnet> wrote:
> 
> >> ... but I see lots of other uses for being able to make triangles
> >> out of primitives.
> >
> >Displacement mapping comes to mind...
> 
> ...and virtual light sources, global ilumination maps, morphing, UV
> mapping...

...and longer parsing times and more memory consumption. Don't forget those.

-- 
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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On Tue, 07 Dec 1999 14:43:13 -0800, Ken <tyl### [at] pacbellnet> wrote:

>
>
>Peter Popov wrote:
>> 
>> On Tue, 07 Dec 1999 09:21:41 -0800, Ken <tyl### [at] pacbellnet> wrote:
>> 
>> >> ... but I see lots of other uses for being able to make triangles
>> >> out of primitives.
>> >
>> >Displacement mapping comes to mind...
>> 
>> ...and virtual light sources, global ilumination maps, morphing, UV
>> mapping...
>
>...and longer parsing times and more memory consumption. Don't forget those.

There's no such thing as a free lunch :(


Peter Popov
pet### [at] usanet
ICQ: 15002700

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