George Hunt wrote:
> 
> On Thu, 13 Nov 1997 11:47:12 -0800, "Ken Cecka" <cec### [at] televarmoc>
> wrote:
> 
> >Since OpenGL is a rendering accelerator, not a ray-tracing accelerator, it
> >is only useful for preview mode in a modeler.  Pov on it's own isn't a
> >modeler, just a ray-tracing engine.  Several of the modelers currently
> >available for POV already use OpenGL for preview though.  Check out sPatch,
> >Breeze, PovSB.  I think they all have OpenGL preview, and I'm sure there are
> >others.
> >
> >Ken
> 
> But Ken,
>     Many people (Dan Farmer for instance, one of the best and best
> known POV-Ray artists ever) don't use modellers at all (or very
> little)  They do in fact use POV-Ray test renders, and a bit of trial
> and error, to 'model' their scenes.  I would say that POV-Ray would be
> all the better if it DID have an option to represent the scene via an
> OpenGL preview.  Then, when you get things in the correct positions
> and get your CSG's etc. correct, you could switch back to a raytraced
> preview so that you can see how the more complex textures are doing.

Well, if you lower POVRays q level, then you can have a lot more speed. 
Enough that OpenGL stll probably wouldn't make much difference.  But you
do raise an interesting point.  What of instead of doing test renders,
you could have a preview window that updated itself everytime it could
parse the source code with out errors.  Meaning that whille you type it
isn't updating the preview, but when you stop you get instant feed
back.  It could also support realtime texturing, so that you could see
if you had the textures possitioned correctly.

Post a reply to this message

This brings up a good questions that I've been wondering about.  Does OpenGL
do realtime CSG?  As far as I know, OpenGL just processes triangle meshes,
not true mathematical objects of the type pov uses.  You would have to
convert your objects to meshes, crunch out the csg's on your processor, and
then send them to the card for display.  That would really defeat the
purpose of pov, since it tries to avoid meshes.  But I really don't know a
lot about OpenGL.  Does it have built in functionality for CSG?

Ken


George Hunt wrote in message <346bf5b9.95268263@news.stmuc.com>...
>On Thu, 13 Nov 1997 11:47:12 -0800, "Ken Cecka" <cec### [at] televarmoc>
>wrote:
>
>>Since OpenGL is a rendering accelerator, not a ray-tracing accelerator, it
>>is only useful for preview mode in a modeler.  Pov on it's own isn't a
>>modeler, just a ray-tracing engine.  Several of the modelers currently
>>available for POV already use OpenGL for preview though.  Check out
sPatch,
>>Breeze, PovSB.  I think they all have OpenGL preview, and I'm sure there
are
>>others.
>>
>>Ken
>
>But Ken,
>    Many people (Dan Farmer for instance, one of the best and best
>known POV-Ray artists ever) don't use modellers at all (or very
>little)  They do in fact use POV-Ray test renders, and a bit of trial
>and error, to 'model' their scenes.  I would say that POV-Ray would be
>all the better if it DID have an option to represent the scene via an
>OpenGL preview.  Then, when you get things in the correct positions
>and get your CSG's etc. correct, you could switch back to a raytraced
>preview so that you can see how the more complex textures are doing.
>
>
>-----------
>George Hunt --- Raytracer Obsessivo
>http://ourworld.compuserve.com/homepages/lightsword
>102### [at] compuservecom
>-----------

Post a reply to this message

I am not an expert on OpenGL, but i belive that OpenGL renders objects by
requiring that they be tesselated into triangles. Fortunately OpenGL
supplies functions for doing this. This is what i gathered from skimming the
SDKs that i have, and it may be incorrect.

Kyle

Ken Cecka wrote in message <346c1929.0@news.povray.org>...
>This brings up a good questions that I've been wondering about.  Does
OpenGL
>do realtime CSG?  As far as I know, OpenGL just processes triangle meshes,
>not true mathematical objects of the type pov uses.  You would have to
>convert your objects to meshes, crunch out the csg's on your processor, and
>then send them to the card for display.  That would really defeat the
>purpose of pov, since it tries to avoid meshes.  But I really don't know a
>lot about OpenGL.  Does it have built in functionality for CSG?
>
>Ken
>...

Post a reply to this message

>     Many people (Dan Farmer for instance, one of the best and best
> known POV-Ray artists ever) don't use modellers at all (or very
> little)  They do in fact use POV-Ray test renders, and a bit of trial
> and error, to 'model' their scenes.  I would say that POV-Ray would be
> all the better if it DID have an option to represent the scene via an
> OpenGL preview.  Then, when you get things in the correct positions
> and get your CSG's etc. correct, you could switch back to a raytraced
> preview so that you can see how the more complex textures are doing.

OpenGL is designed mainly to accelerate animations - manipulating 3D
objects in real-time - and so the effect on static renders probably
wouldn't be worthwhile. If you're looking to do lower-quality previews
while developing a scene, POV-Ray has the command line switches to do
that already - I think it's +Qx where 0<=x<=9, I used to use it a lot
when running on a 486 but nowadays I use the mosaic preview for quicker
test renders.

Post a reply to this message

George Hunt wrote:

> But Ken,
>     Many people (Dan Farmer for instance, one of the best and best
> known POV-Ray artists ever) don't use modellers at all (or very
> little)  They do in fact use POV-Ray test renders, and a bit of trial
> and error, to 'model' their scenes.  I would say that POV-Ray would be
> all the better if it DID have an option to represent the scene via an
> OpenGL preview.  Then, when you get things in the correct positions
> and get your CSG's etc. correct, you could switch back to a raytraced
> preview so that you can see how the more complex textures are doing.

Best as in how well he knew POVRay?  Or best artist.  I can model
complex objects in POVRay with out using a seperate modeller, but why
would I want to?  It stifles creativity.  I do all my texturing by hand
in POVRay, and even tweak modelels in POVRay sometimes.

When we take away limitating ourselves to POVRay, I think that we will
find that many of the best artists use a really powerfull modeller like
Rhino, Max, Lightwave, Alias, FormZ or whatever.  Even if they then go
on and use a different renderer (be it POVRay, or MentalRay).  Not doing
it by hand in POVRay.

Post a reply to this message

I agree with you 100%. OpenGL can help a lot when someone debugs a
geometrically complex scene (placements, geometry, sizes) when it is
not practical to use small previews. It may not help to test lights and
textures but anyway it will be _very_ useful piece of functionality.

My wish list for future versions of POV-Ray:

General: OpenGL preview and multiprocessor capabilities.
Windows-specific: (possibly) Direct3D preview, full MMX support.

Reasons: I see OpenGL and DirectX as the only reasonable way to support
platform-specific hardware- (and software-) assisted acceleration. All new
processors are MMX-capable and it is a crime not to use accelerating
facilities for computing power-hungry apps :-). Now when memory prices are
going down and Intel processors are dirt cheap, it is practical and
inexpensive
to have a dual processor computer under NT or whatever you like. There is
a number of multiprocessor UNIX computers out there. A lot of people buy
dual-processor motherboards counting on future upgrades by adding second
CPU. I believe it should be supported eventually.

Eugene

-- Eugene Lazutkin (eug### [at] ABCcarnac-graphicscom) hint: remove ABC

George Hunt wrote in message <346bf5b9.95268263@news.stmuc.com>...
>On Thu, 13 Nov 1997 11:47:12 -0800, "Ken Cecka" <cec### [at] televarmoc>
>wrote:
>
>>Since OpenGL is a rendering accelerator, not a ray-tracing accelerator, it
>>is only useful for preview mode in a modeler.  Pov on it's own isn't a
>>modeler, just a ray-tracing engine.  Several of the modelers currently
>>available for POV already use OpenGL for preview though.  Check out
sPatch,
>>Breeze, PovSB.  I think they all have OpenGL preview, and I'm sure there
are
>>others.
>>
>>Ken
>
>But Ken,
>    Many people (Dan Farmer for instance, one of the best and best
>known POV-Ray artists ever) don't use modellers at all (or very
>little)  They do in fact use POV-Ray test renders, and a bit of trial
>and error, to 'model' their scenes.  I would say that POV-Ray would be
>all the better if it DID have an option to represent the scene via an
>OpenGL preview.  Then, when you get things in the correct positions
>and get your CSG's etc. correct, you could switch back to a raytraced
>preview so that you can see how the more complex textures are doing.
>
>
>-----------
>George Hunt --- Raytracer Obsessivo
>http://ourworld.compuserve.com/homepages/lightsword
>102### [at] compuservecom
>-----------

Post a reply to this message

Eugene Lazutkin wrote:

> I agree with you 100%. OpenGL can help a lot when someone debugs a
> geometrically complex scene (placements, geometry, sizes) when it is
> not practical to use small previews. It may not help to test lights
> and
> textures but anyway it will be _very_ useful piece of functionality.
>
> My wish list for future versions of POV-Ray:
>
> General: OpenGL preview and multiprocessor capabilities.
> Windows-specific: (possibly) Direct3D preview, full MMX support.
>
> Reasons: I see OpenGL and DirectX as the only reasonable way to
> support
> platform-specific hardware- (and software-) assisted acceleration. All
> new
> processors are MMX-capable and it is a crime not to use accelerating
> facilities for computing power-hungry apps :-). Now when memory prices
> are
> going down and Intel processors are dirt cheap, it is practical and
> inexpensive
> to have a dual processor computer under NT or whatever you like. There
> is
> a number of multiprocessor UNIX computers out there. A lot of people
> buy
> dual-processor motherboards counting on future upgrades by adding
> second
> CPU. I believe it should be supported eventually.
>
> Eugene

Note that as far as I know OpenGL has no good way to do CSG - and some
other correspondences between OpenGL and POV language do not relate.
Also, as for OpenGL and DirectX, Microsoft and SGI have just announced
they will work together with their two respective technologies to merge
them into a better standard for 3D on the PC. Read their release at
microsoft.com or opengl.org or sgi.com. The people I have talked with,
and myself, think this is a great move.

OpenGL previews would most likely be limited to basic shapes, in my
opinion.

jon

Post a reply to this message

I am talking about preview mode to test geometry, placements, sizes and
so on (see my original post). I am aware that it is not possible to recreate
the exact picture with OpenGL or Direct3D. But we can approximate :-).
We can simulate complex shapes with basic ones.

Sometimes I need rather crude picture but I can't use small previews
because my picture consists of a number of small objects. In this case
what I need is _raw speed_.

I know about future convergence between OpenGL and DirectX and I
welcome it. But they will be distinct at least for 5 more years: first
commercial version of low-level API is scheduled on Y2K and it will
need some polish (you can trust me on that :-) ) and don't forget about
legacy UNIX systems which will support good old OpenGL for their
lifetime :-).

Eugene

Jon S. Berndt wrote in message <34A50D56.A31FDCF9@hal-pc.org>...
>Eugene Lazutkin wrote:
>
>> I agree with you 100%. OpenGL can help a lot when someone debugs a
>> geometrically complex scene (placements, geometry, sizes) when it is
>> not practical to use small previews. It may not help to test lights
>> and
>> textures but anyway it will be _very_ useful piece of functionality.
>>
>> My wish list for future versions of POV-Ray:
>>
>> General: OpenGL preview and multiprocessor capabilities.
>> Windows-specific: (possibly) Direct3D preview, full MMX support.
>>
>> Reasons: I see OpenGL and DirectX as the only reasonable way to
>> support
>> platform-specific hardware- (and software-) assisted acceleration. All
>> new
>> processors are MMX-capable and it is a crime not to use accelerating
>> facilities for computing power-hungry apps :-). Now when memory prices
>> are
>> going down and Intel processors are dirt cheap, it is practical and
>> inexpensive
>> to have a dual processor computer under NT or whatever you like. There
>> is
>> a number of multiprocessor UNIX computers out there. A lot of people
>> buy
>> dual-processor motherboards counting on future upgrades by adding
>> second
>> CPU. I believe it should be supported eventually.
>>
>> Eugene
>
>Note that as far as I know OpenGL has no good way to do CSG - and some
>other correspondences between OpenGL and POV language do not relate.
>Also, as for OpenGL and DirectX, Microsoft and SGI have just announced
>they will work together with their two respective technologies to merge
>them into a better standard for 3D on the PC. Read their release at
>microsoft.com or opengl.org or sgi.com. The people I have talked with,
>and myself, think this is a great move.
>
>OpenGL previews would most likely be limited to basic shapes, in my
>opinion.
>
>jon
>

Post a reply to this message

A quick preview of geometry will not be any more efficient without big
complicated geometry (maths side of things) acceleration hardware. OpenGL
and Direct3D require Meshes, and it can take a while to come up with a mesh
for small objects compared to rendering them with low quality flags (we are
talking two light sources - ambient and a directional source, only ambient
and diffuse shading on objects - no shadows - no reflection or refraction).

You can render a high resolution image in under a second. How long will it
take to parse a complex scene into meshes for rendering with OpenGL?

A new version of povray for windows could parse a .pov file when it is
opened, and preview, then as you change the file, look up in a table made
at parse time for what object you are editing, then re-render. A preview
window could even have a text box for clock value, and a drop down for you
to select declared objects names from any open file (eg if you are editing
an inc that calculates rand numbers for transformations, you could have
selected an object declared in another file that uses these random
numbers).

-- 
Tristan Wibberley

(Remove the '.NO_LUNCHEON_MEAT' from my
email address to reply.)


Eugene Lazutkin <eug### [at] carnac-graphicscom> wrote in article
<34b66582.0@news.povray.org>...
| I am talking about preview mode to test geometry, placements, sizes and
| so on (see my original post). I am aware that it is not possible to
recreate
| the exact picture with OpenGL or Direct3D. But we can approximate :-).
| We can simulate complex shapes with basic ones.
| 
| Sometimes I need rather crude picture but I can't use small previews
| because my picture consists of a number of small objects. In this case
| what I need is _raw speed_.
| 
| I know about future convergence between OpenGL and DirectX and I
| welcome it. But they will be distinct at least for 5 more years: first
| commercial version of low-level API is scheduled on Y2K and it will
| need some polish (you can trust me on that :-) ) and don't forget about
| legacy UNIX systems which will support good old OpenGL for their
| lifetime :-).
| 
| Eugene
| 
| Jon S. Berndt wrote in message <34A50D56.A31FDCF9@hal-pc.org>...
| >Eugene Lazutkin wrote:
| >
| >> I agree with you 100%. OpenGL can help a lot when someone debugs a
| >> geometrically complex scene (placements, geometry, sizes) when it is
| >> not practical to use small previews. It may not help to test lights
| >> and
| >> textures but anyway it will be _very_ useful piece of functionality.
| >>
| >> My wish list for future versions of POV-Ray:
| >>
| >> General: OpenGL preview and multiprocessor capabilities.
| >> Windows-specific: (possibly) Direct3D preview, full MMX support.
| >>
| >> Reasons: I see OpenGL and DirectX as the only reasonable way to
| >> support
| >> platform-specific hardware- (and software-) assisted acceleration. All
| >> new
| >> processors are MMX-capable and it is a crime not to use accelerating
| >> facilities for computing power-hungry apps :-). Now when memory prices
| >> are
| >> going down and Intel processors are dirt cheap, it is practical and
| >> inexpensive
| >> to have a dual processor computer under NT or whatever you like. There
| >> is
| >> a number of multiprocessor UNIX computers out there. A lot of people
| >> buy
| >> dual-processor motherboards counting on future upgrades by adding
| >> second
| >> CPU. I believe it should be supported eventually.
| >>
| >> Eugene
| >
| >Note that as far as I know OpenGL has no good way to do CSG - and some
| >other correspondences between OpenGL and POV language do not relate.
| >Also, as for OpenGL and DirectX, Microsoft and SGI have just announced
| >they will work together with their two respective technologies to merge
| >them into a better standard for 3D on the PC. Read their release at
| >microsoft.com or opengl.org or sgi.com. The people I have talked with,
| >and myself, think this is a great move.
| >
| >OpenGL previews would most likely be limited to basic shapes, in my
| >opinion.
| >
| >jon
| >
| 
| 
|

Post a reply to this message

As far as I understood, your biggest concern is a speed of conversion
from a some-complex-object to a mesh. I do believe that it will not be a
bottleneck in most cases providing we are not going to recreate our scene
with a PovRay quality. Exact "approximation" of sphere has infinite number
of triangles ;-). We don't need _that_ in a preview mode.

Years ago I was surprised that bezier-based approximation working with
1-pixel precision draws circles virtually identical to ones produced be
"real" math formula. A number of lines produced by bezier was relatively
low. And a raw speed is incomparable (bezier is faster)! So far I didn't
see any real life examples, which don't benefit from an approximation.
Of course some quality can be lost.

If new version of PovRay could parse a file on the fly or in the background,
the same techniques can be applied: as you change the file it can convert
only changed parts. You don't need to convert a PovRay file to some other
graphics primitives every time. You can store this information in a
persistent "cache" file specific to the driver (OpenGL, D3D or whatever
you have). How to support it up-to-date? You already said about lookup
tables and there are zillions of other possible solutions for external-data-
to-internal-cache problem.

If we look at really simplistic cases like the Turok game, we will see that
all 3D accelerators outperform any known software-based renderers (i.e.,
see excellent Tom's Hardware Guide @ http://www.tomshardware.com/
for some numbers and pics). Speaking for myself, I do try to use some
obscure visual effects and unusual shapes in my scenes which are not
possible to recreate with Voodoo2 :-) but usually my geometry is not
more complex than some complex scenes in the Quake II or the Turok.
I wish I was able to render at their speed!

...And MMX can help too. :-) ...And multiprocessing is very helpful. :-)

Cheers,

Eugene

Tristan Wibberley wrote in message
<01bd36e9$46e16b60$181657a8@W_tristan.gb.tandem.com>...
>A quick preview of geometry will not be any more efficient without big
>complicated geometry (maths side of things) acceleration hardware. OpenGL
>and Direct3D require Meshes, and it can take a while to come up with a mesh
>for small objects compared to rendering them with low quality flags (we are
>talking two light sources - ambient and a directional source, only ambient
>and diffuse shading on objects - no shadows - no reflection or refraction).
>
>You can render a high resolution image in under a second. How long will it
>take to parse a complex scene into meshes for rendering with OpenGL?
>
>A new version of povray for windows could parse a .pov file when it is
>opened, and preview, then as you change the file, look up in a table made
>at parse time for what object you are editing, then re-render. A preview
>window could even have a text box for clock value, and a drop down for you
>to select declared objects names from any open file (eg if you are editing
>an inc that calculates rand numbers for transformations, you could have
>selected an object declared in another file that uses these random
>numbers).
>
>--
>Tristan Wibberley
>
>(Remove the '.NO_LUNCHEON_MEAT' from my
>email address to reply.)
>
>
>Eugene Lazutkin <eug### [at] carnac-graphicscom> wrote in article
><34b66582.0@news.povray.org>...
>| I am talking about preview mode to test geometry, placements, sizes and
>| so on (see my original post). I am aware that it is not possible to
>recreate
>| the exact picture with OpenGL or Direct3D. But we can approximate :-).
>| We can simulate complex shapes with basic ones.
>|
>| Sometimes I need rather crude picture but I can't use small previews
>| because my picture consists of a number of small objects. In this case
>| what I need is _raw speed_.
>|
>| I know about future convergence between OpenGL and DirectX and I
>| welcome it. But they will be distinct at least for 5 more years: first
>| commercial version of low-level API is scheduled on Y2K and it will
>| need some polish (you can trust me on that :-) ) and don't forget about
>| legacy UNIX systems which will support good old OpenGL for their
>| lifetime :-).
>|
>| Eugene
>|
>| Jon S. Berndt wrote in message <34A50D56.A31FDCF9@hal-pc.org>...
>| >Eugene Lazutkin wrote:
>| >
>| >> I agree with you 100%. OpenGL can help a lot when someone debugs a
>| >> geometrically complex scene (placements, geometry, sizes) when it is
>| >> not practical to use small previews. It may not help to test lights
>| >> and
>| >> textures but anyway it will be _very_ useful piece of functionality.
>| >>
>| >> My wish list for future versions of POV-Ray:
>| >>
>| >> General: OpenGL preview and multiprocessor capabilities.
>| >> Windows-specific: (possibly) Direct3D preview, full MMX support.
>| >>
>| >> Reasons: I see OpenGL and DirectX as the only reasonable way to
>| >> support
>| >> platform-specific hardware- (and software-) assisted acceleration. All
>| >> new
>| >> processors are MMX-capable and it is a crime not to use accelerating
>| >> facilities for computing power-hungry apps :-). Now when memory prices
>| >> are
>| >> going down and Intel processors are dirt cheap, it is practical and
>| >> inexpensive
>| >> to have a dual processor computer under NT or whatever you like. There
>| >> is
>| >> a number of multiprocessor UNIX computers out there. A lot of people
>| >> buy
>| >> dual-processor motherboards counting on future upgrades by adding
>| >> second
>| >> CPU. I believe it should be supported eventually.
>| >>
>| >> Eugene
>| >
>| >Note that as far as I know OpenGL has no good way to do CSG - and some
>| >other correspondences between OpenGL and POV language do not relate.
>| >Also, as for OpenGL and DirectX, Microsoft and SGI have just announced
>| >they will work together with their two respective technologies to merge
>| >them into a better standard for 3D on the PC. Read their release at
>| >microsoft.com or opengl.org or sgi.com. The people I have talked with,
>| >and myself, think this is a great move.
>| >
>| >OpenGL previews would most likely be limited to basic shapes, in my
>| >opinion.
>| >
>| >jon
>| >
>|
>|
>|

Post a reply to this message