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I am wondering about adding an OpenGL preview for animations. I have three
questions.
- Would it be legal to distribute since OpenGL would be doing the
rendering and povray would only be doing the parsing?
- Is it being done already?
- Is it somthing that the povray comunity would be interested in using?
(besides me)
I am thinking of just using it for very fast test renders, using quick
colors instead of real textures and simple lights so you can see how the
objects look and how the camera moves. You could then tweak it very
finely for animations since the edit/render/view cycle would be shorter.
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In article <3a632dad@news.povray.org>, "David C" <dav### [at] sat net>
wrote:
> I am wondering about adding an OpenGL preview for animations. I have three
> questions.
This would probably be harder than you think...the code for setting up
OpenGL would be platform dependant, and you would have to use something
like Warp's tesselation patch, because most objects are rendered
directly, not tesselated.
> - Would it be legal to distribute since OpenGL would be doing the
> rendering and povray would only be doing the parsing?
I don't think there would be a problem, as long as the version you are
distributing consists of everything in the official version of POV
*plus* optional OpenGL rendering. (You couldn't release a version that
only does OpenGL previews.) I'm not sure though, I will check with the
POV-Team.
> - Is it being done already?
If so, nobody has said anything about it. I doubt it, for the reasons I
mentioned above.
> - Is it somthing that the povray comunity would be interested in using?
> (besides me)
Almost definitely.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <chrishuff-AECD5C.12452115012001@news.povray.org>, "Chris Huff"
<chr### [at] maccom> wrote:
> This would probably be harder than you think...the code for setting up
> OpenGL would be platform dependant, and you would have to use something
> like Warp's tesselation patch, because most objects are rendered
> directly, not tesselated.
I know about how the objects are rendered. I was thinking of using the
glut library so that it would be platform independent. I really havn't
put too much thought into this. It's just a really neat idea I had that I
may or may not write.
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David,
Have you thought much about how you would handle CSG? I don't know
anything about Warp's tesselation patch that Chris referred to, but CSG can
be a show-stopper. Finding an algorithm to generate meshes for arbitrary
CSG combinations is difficult. Usually you end up with a tradeoff between
speed and accuracy. For a static OpenGL display, the algorithm doesn't
need to be particularly fast since you only calculate the mesh once, and
then are free to explore your scene with a mobile camera (fun!). If you
want animation, you need to be able to quickly recalculate CSG meshes
(consider a scene with a difference of two spheres, where one of the
spheres slides from left to right during the animation).
I've actually written a lot of code to solve this exact problem (since I
figured almost any other primitive POV uses will be easy to tesselate), and
have pretty well given up on it, although I still fiddle with it from time
to time. There are some fundamental problems in the approach I was taking
that I haven't seen a way to solve yet. I can go into more detail on what
I've tried and some of my conclusions if you're interested.
Ken
David C wrote:
> I am wondering about adding an OpenGL preview for animations. I have three
> questions.
>
> - Would it be legal to distribute since OpenGL would be doing the
> rendering and povray would only be doing the parsing?
> - Is it being done already?
> - Is it somthing that the povray comunity would be interested in using?
> (besides me)
>
> I am thinking of just using it for very fast test renders, using quick
> colors instead of real textures and simple lights so you can see how the
> objects look and how the camera moves. You could then tweak it very
> finely for animations since the edit/render/view cycle would be shorter.
>
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In article <3a6353dd$1@news.povray.org>, "David C" <dav### [at] satnet>
wrote:
> I know about how the objects are rendered. I was thinking of using the
> glut library so that it would be platform independent. I really havn't
> put too much thought into this. It's just a really neat idea I had that I
> may or may not write.
Hmm...if you use the GLUT library, you gain platform independance (you
will only need to recompile for most platforms), but it kind of limits
you...I don't think you can combine GLUT with platform-dependant
interfaces, and GLUT was mainly designed for tests and demos. Maybe a
GLUT interface, but make sure you keep the GLUT-dependant code well
separated and provide plenty of ways to use other platform-specific
interfaces instead.
And GLUT still won't help you render many POV primitives...julia
fractals, for instance.
And what extent of previewing were you thinking of? An immediate preview
of each frame and writing those results to the output file, or rendering
all frames (without displaying) and displaying them all at once? For
stills, a way to move camera and lights around without reparsing the
file? (that last one could be really platform/GLUT dependant...)
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <3a635d70@news.povray.org>, Ken Cecka
<cec### [at] alumniwashingtonedu> wrote:
> Have you thought much about how you would handle CSG? I don't know
> anything about Warp's tesselation patch that Chris referred to, but
> CSG can be a show-stopper. Finding an algorithm to generate meshes
> for arbitrary CSG combinations is difficult. Usually you end up with
> a tradeoff between speed and accuracy.
Warp's code uses the marching tetrahedrons algorithm and can handle any
arbitrary shape, including CSG. There is a speed/accuracy/memory
tradeoff...and the meshes aren't as optimized as they could if you made
them yourself, but it works, and OpenGL would just be a preview, so you
wouldn't even need very high quality meshes.
> For a static OpenGL display, the algorithm doesn't need to be
> particularly fast since you only calculate the mesh once, and then
> are free to explore your scene with a mobile camera (fun!).
I'm not clear on whether he is working on that kind of interactive
display or simply using OpenGL for extremely fast preview images.
> If you want animation, you need to be able to quickly recalculate CSG
> meshes (consider a scene with a difference of two spheres, where one
> of the spheres slides from left to right during the animation).
Or just compute all the images and play back the results. Or just do
things the way POV does them now, only using OpenGL to do the rendering
instead of the raytracing engine.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <chrishuff-C2A809.16204115012001@news.povray.org>, "Chris Huff"
<chr### [at] maccom> wrote:
>
>
> Or just compute all the images and play back the results. Or just do
> things the way POV does them now, only using OpenGL to do the rendering
> instead of the raytracing engine.
I was originally thinking of just using opengl as a relatively superfast
way to render animations exactly how povray does it so you can see how
they look. I personally can't see many practical reasons you would need to move
around in the world other than the camera defined in the pov file.
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In article <chrishuff-2E3292.16145515012001@news.povray.org>, "Chris Huff"
<chr### [at] maccom> wrote:
>
>
> And what extent of previewing were you thinking of? An immediate preview
> of each frame and writing those results to the output file, or
> rendering all frames (without displaying) and displaying them all at
> once? For stills, a way to move camera and lights around without
> reparsing the file? (that last one could be really platform/GLUT
> dependant...)
>
I have thought about some of these things too. I might have a framerate
problem if I tried to render the animation in real time. There is no fps
option in povray as well, so I wouldn't know the user's desired
framerate. I think definitely that each frame should be rendered and
written to a file. I'm not sure about real time previewing. There is also
the matter of how to get the frame from opengl to a file. I know some
libraries support offscreen rendering, but that again would be platform
dependent. Ah well. Maybe I should play with opengl and get comfortable
with it for a few weeks first.
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In article <3a63a683$1@news.povray.org>, "David C" <dav### [at] satnet>
wrote:
> I was originally thinking of just using opengl as a relatively
> superfast way to render animations exactly how povray does it so you
> can see how they look. I personally can't see many practical reasons
> you would need to move around in the world other than the camera
> defined in the pov file.
That should be easier to write and keep platform independant, too. And
more likely to get working right...
How do you plan on doing different camera types? As far as I know,
OpenGL only does perspective and orthographic projection. You might have
to issue a warning when another type is used and use perspective
projection in those cases...that shouldn't be a problem for quick
preview renders.
Practical reasons: it could make it easier to get camera position/angle
and general lighting right, but it really would be the job of a
third-party modeller.
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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In article <chrishuff-752B67.20502515012001@news.povray.org>, "Chris Huff"
<chr### [at] maccom> wrote:
> That should be easier to write and keep platform independant, too. And
> more likely to get working right... How do you plan on doing different
> camera types? As far as I know, OpenGL only does perspective and
> orthographic projection. You might have to issue a warning when another
> type is used and use perspective projection in those cases...that
> shouldn't be a problem for quick preview renders.
Well I wasn't thinking of fully supporting all of povray's stuff like
some of the different light types that don't have a native equivelent in
opengl. And then, there's transparency, reflections, refractions,
povray's function-textures, media, imagemaps, and maybe a few more
I havn't thought of.
> Practical reasons: it could make it easier to get camera position/angle
> and general lighting right, but it really would be the job of a
> third-party modeller.
In order to get camera position and angle, there would need to be a way
to output the current values that the camera has which would make opengl
rendering even more different than povray raytracing. I think, if I do
actually start building it, that I'd try to mimic the behavior of native
rendering as much as possible. For me, this is all just talk so far. I'd
love to do it, but I'm not sure I will.
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In article <3a63a872@news.povray.org>, "David C" <dav### [at] satnet>
wrote:
> I have thought about some of these things too. I might have a framerate
> problem if I tried to render the animation in real time. There is no fps
> option in povray as well, so I wouldn't know the user's desired
> framerate. I think definitely that each frame should be rendered and
> written to a file. I'm not sure about real time previewing.
Real time previewing definitely wouldn't be possible...the parse time
would reduce it to a couple seconds a frame for simple scenes, and I've
had scenes that went for nearly an hour just parsing. To get an animated
preview, you would pretty much have to save the frames as they are
calculated, and then display them. It would be simpler and more
consistent to treat OpenGL rendering just like ordinary rendering.
> There is also the matter of how to get the frame from opengl to a
> file. I know some libraries support offscreen rendering, but that
> again would be platform dependent.
I'm pretty sure there are standard functions for getting the image data
(glReadPixels()?), and the code for setting up the OpenGL context and
stuff should be separated out into a platform-dependant section anyway.
> Ah well. Maybe I should play with opengl and get comfortable with it
> for a few weeks first.
If you need help, I am also learning OpenGL and may be able to help you
find some resources...
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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On Mon, 15 Jan 2001 21:00:55 +0600 David C wrote:
>Well I wasn't thinking of fully supporting all of povray's stuff like
>some of the different light types that don't have a native equivelent in
>opengl. And then, there's transparency, reflections, refractions,
>povray's function-textures, media, imagemaps, and maybe a few more
>I havn't thought of.
David, I think it comes down to whether or not you want to spend the
time to write the OpenGL code with its inherent limitations or be
satisfied with using the already built-in quality settings in POV-Ray,
as per docs section 3.2.6.1 "Quality Settings".
--
Alan - ako### [at] povrayorg - a k o n g <at> p o v r a y <dot> o r g
http://www.povray.org - Home of the Persistence of Vision Ray Tracer
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David C wrote:
>
> I am wondering about adding an OpenGL preview for animations. I have three
> questions.
>
> - Would it be legal to distribute since OpenGL would be doing the
> rendering and povray would only be doing the parsing?
> - Is it being done already?
> - Is it somthing that the povray comunity would be interested in using?
> (besides me)
>
> I am thinking of just using it for very fast test renders, using quick
> colors instead of real textures and simple lights so you can see how the
> objects look and how the camera moves. You could then tweak it very
> finely for animations since the edit/render/view cycle would be shorter.
I haven't followed Moray development recently, but at some time it had
animation plugin, which allowed to see animations relatively easy from
Moray (but rendering was done with Polyray dll, IIRC). Moray is for
Windows only of course, so not much for multiplatform support, but if
one can stand modeller and uses Windows, then it might be solution.
Then, couple of years ago Johannes Hubert wrote basic POV-Ray animation
program in OpenGL for the IMP. He used POB patch for handling POV-Ray
objects and displaying them. IIRC this program worked with primitives
only and was written in very short time so it didn't provided very much
functionality. Johannes is not seen recently and AFAIK he didn't
released source code for this program. Additionally, POB patch was for
older version of POV-Ray and AFAIK it is not updated for recent
version(s).
So, seems like you are on your own. RT animation would be nice, but I'm
not sure, that POV-Ray is the best program for doing this...
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> Have you thought much about how you would handle CSG? I don't know
> anything about Warp's tesselation patch that Chris referred to, but CSG
can
> be a show-stopper. Finding an algorithm to generate meshes for arbitrary
> CSG combinations is difficult.
Moray manages to evaluate csg quite happily (with opengl) however it can be
slow for complex operations, so for use in a animation preview system it may
take (in some cases) almost as long to evaluate the csg as it would to
render it normally.
--
Rick
POV-Ray News & Resources - http://povray.co.uk
Kitty5 WebDesign - http://kitty5.com
Hi-Impact web site design & database driven e-commerce
TEL : +44 (01625) 266358 - FAX : +44 (01625) 611913 - ICQ : 15776037
PGP Public Key
http://pgpkeys.mit.edu:11371/pks/lookup?op=get&search=0x231E1CEA
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I'd encourage you to do this. There is a real need for this kind of
functionality.
Also, please ignore the nay-sayers. Every time this subject comes up, a
number of POV participants jump on the head of the suggestor and flog the
suggestor mercilessly. Ignore them and do what you think is right.
Jim
http://www.kressworks.com/
"David C" <dav### [at] satnet> wrote in message news:3a632dad@news.povray.org...
> I am wondering about adding an OpenGL preview for animations. I have three
> questions.
>
> - Would it be legal to distribute since OpenGL would be doing the
> rendering and povray would only be doing the parsing?
> - Is it being done already?
> - Is it somthing that the povray comunity would be interested in using?
> (besides me)
>
> I am thinking of just using it for very fast test renders, using quick
> colors instead of real textures and simple lights so you can see how the
> objects look and how the camera moves. You could then tweak it very
> finely for animations since the edit/render/view cycle would be shorter.
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David C wrote:
> - Is it somthing that the povray comunity would be interested in using?
> (besides me)
I have some particle-based animations that would be neat to let run like all
day as either a screensaver for entertainment value or to explore the "steady
state" condition after thousands of frames. I'd like to keep it in povray
scene language syntax because then I could easily put it all back to make
"real" animations when I'm done.
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In article <3a63b91e@news.povray.org>, "David C" <dav### [at] satnet>
wrote:
> Well I wasn't thinking of fully supporting all of povray's stuff like
> some of the different light types that don't have a native equivelent in
> opengl. And then, there's transparency, reflections, refractions,
> povray's function-textures, media, imagemaps, and maybe a few more
> I havn't thought of.
I certainly wasn't suggesting you should try to support all of
that...just shadowless point lights, ambient lighting, solid colors, and
orthographic and perspective cameras would be enough, at least at first.
> I think, if I do actually start building it, that I'd try to mimic
> the behavior of native rendering as much as possible.
Probably a good idea.
> For me, this is all just talk so far. I'd love to do it, but I'm not
> sure I will.
It would be an interesting project...and might keep Warp's mesh patch
alive long enough for someone to fix it. ;-)
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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Alan Kong wrote:
> David, I think it comes down to whether or not you want to spend the
thinking 'Huh? What's this?' scrolling up, 'oh, David C' a "senior moment" as
it were
--
David Fontaine <dav### [at] faricynet> ICQ 55354965
My raytracing gallery: http://davidf.faricy.net/
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Jim Kress wrote:
>
> I'd encourage you to do this. There is a real need for this kind of
> functionality.
>
> Also, please ignore the nay-sayers. Every time this subject comes up, a
> number of POV participants jump on the head of the suggestor and flog the
> suggestor mercilessly. Ignore them and do what you think is right.
It's blasphemy, Jim. I say nay ! We never had it before so why do we
need it now ? OGL is crappy compared to raytracing. Might as well add
gif output support as long as we are going backwards. I don't like the
idea. You want to do what ? Never had it, never will.
<g>
--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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LOL!
You've decided to become a "say nayer" rather than a "nay sayer"?
Jim
"Ken" <tyl### [at] pacbellnet> wrote in message
news:3A6536C8.70DFA792@pacbell.net...
>
>
> Jim Kress wrote:
> >
> > I'd encourage you to do this. There is a real need for this kind of
> > functionality.
> >
> > Also, please ignore the nay-sayers. Every time this subject comes up, a
> > number of POV participants jump on the head of the suggestor and flog
the
> > suggestor mercilessly. Ignore them and do what you think is right.
>
> It's blasphemy, Jim. I say nay ! We never had it before so why do we
> need it now ? OGL is crappy compared to raytracing. Might as well add
> gif output support as long as we are going backwards. I don't like the
> idea. You want to do what ? Never had it, never will.
>
> <g>
>
> --
> Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
> http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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In article <3a632dad@news.povray.org>, "David C" <dav### [at] satnet>
wrote:
> - Would it be legal to distribute since OpenGL would be doing the
> rendering and povray would only be doing the parsing?
Well, there don't seem to be any objections from the POV-Team, since
OpenGL is cross-platform and wouldn't affect normal operation of the
program. And now that the tesselation patch has been released, it should
be quite possible...
I'd start by adding Tesselate() and DrawOpenGL() methods to each object.
The default Tesselate() method would use Warp's code, but object
specific ones could be added later. The default DrawOpenGL() method
would use the Tesselate() method of the object to generate a mesh (maybe
using some global settings or per-object defaults for quality), and use
that to draw the object, but again could be implemented separately for
specific objects.
It might be a good idea to add an object type variable in the process,
it could make some things quite a bit easier. Adding Tesselate() methods
will be necessary for some stuff I'm doing, maybe we should work
together on some of the stuff to make sure the separate patches are
compatable.
Maybe factor out the mesh data stuff into a separate area of code so it
isn't mesh object specific, this might be useful for when you need mesh
data but aren't rendering it directly, but likely a lot of work. It may
be better just to pass mesh objects around.
What do you think?
--
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/
<><
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