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Pabs wrote:
>
> Vahur Krouverk wrote:
>
> > Hello!
> > I really hope, that this patch is useful for someone and not very much
> > of bugs is left there...
>
> (Win version)
> All the demos use shader files with the extension .slp
> whereas the example shader files use the extension .sl
> When I change these to the right name I get a "Shader error: badly formed
> input file." error
> What does that mean.
>
This means that You tried to use source file instead of using
byte-compiled one. In order to get compiled shader, type:
c:>povslc shader.sl
this creates shader.slp, which contains byte-code.
You read documentation, didn't You?
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ryan constantine wrote:
>
> which pov version is your patch based on? are there good shader tut's
> out there? urls anyone?
>
It's based on MegaPov 0.6a (latest one).
Best and most comprehensive reference is in pixar site:
http://www.pixar.com/products/renderman/toolkit/RISpec/section8.html
http://www.pixar.com/products/renderman/toolkit/Toolkit/slextensions.html
I guess that those, who use POV-Ray, should be able to read it without
problems.
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Warp wrote:
>
> It would have been interesting if you had provided some benchmark results
> (eg. how much time does it take to render a shader compared to a regular and
> similar texture, etc).
>
Of course, but I've developed it on 486/DX2 66MHz and this is not just
best box for benchmarks.
Now when I have Windows version, I try to perform tests on my working
machine (PII 350Mhz).
But results of some tests (this was on performed on Linux with debug
version):
Pure shader call (well, almost, it assigned red to surface color)
increased execution time 33 % (pure POV-Ray executed scene 15 seconds,
with shader it took time 20 seconds). Main overhead comes from memory
management (separate shader instance is allocated each time in order to
be reentrant), if I tried it without allocation, then time was almost
same (16.xx sec). So there is area for improvement (one possibility it
to preallocate shader instances).
When shader has more code, then difference will be bigger: e.g. povshad
scene, which renders one sphere with POV-Ray shading, other with shader
language, has following results:
Pure POV-Ray sphere: 12 seconds
Shader sphere : 38 seconds
Here probably illuminance loop, which is executed for shading, incurs
such an overhead. Alas, this is the price for flexibility.
However, I consider it as beta version and with this release I wanted to
test, whether there is enough interest for such patch. So far I've tried
to make it correct, performance has not been my major concern. In future
I will tinker with performance buttons and knobs more.
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Vahur Krouverk wrote:
> You read documentation, didn't You?
Obviously not well enough :)
Perhaps you could have a system similar to photon mapping where you can ask POV
to compile the shader (call povslc) to a file if it has not been compiled
previously.
--
Bye
Pabs
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ryan constantine wrote:
> are there good shader tut's out there? urls anyone?
Here is link to one SL tutorial:
http://minerva.ca.scad.edu/faculty/kesson/CA301/shading/surf.htm
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"Vahur Krouverk" <vah### [at] aetec ee> wrote :
>
> I guess that those, who use POV-Ray, should be able to read it without
> problems.
So if I spend the time to learn shaders, is it likely that in the future
there will be an effort to include renderman standards in the official
Pov-ray? Or would I be learning for the patch and nothing else?
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Bill DeWitt wrote:
>
> "Vahur Krouverk" <vah### [at] aetecee> wrote :
> >
> > I guess that those, who use POV-Ray, should be able to read it without
> > problems.
>
> So if I spend the time to learn shaders, is it likely that in the future
> there will be an effort to include renderman standards in the official
> Pov-ray?
This should be asked from POV-Ray team, as I don't have enough authority
to comment on this one. But I do hope that this happens sometime in
future.
One problem could be legal issue: can freeware (such as POV-Ray) use
language, which is used and created for commercial program? I know, that
there is effort to make GPL-ed RenderMan implementation and several
other implementations are available and I hope, that Pixar will not put
it's hand on way, but there is always possibility, that money will talk
louder than common sense. So far, so good...
> Or would I be learning for the patch and nothing else?
Why nothing else? Learning per se is good thing ;o) I personally have
learned great deal of CG stuff (and other things) during creation of
this patch, so at least one person has already benefitted from this
patch. Using Shading Language is good for profound knowledge of CG.
I personally don't think, that Shading Language _itself_ is complex,
especially for those, who know C and CG basics. But _creating_ _good_
shaders is quite complex and knowledge demanding task and not for
everyone. One has to know math (geometry, differential analysis for
antialiasing), physics, optics etc.
This is the reason, why I want to make POV-Ray support for it as
compatible as possible to RenderMan's standard: this way POV-Ray users
can reuse existing and available shaders by modifying only shader input
parameters, which shouldn't be more difficult, than specifying
parameters for some POV-Ray feature (such as radiocity). And advanced
users can tinker with shader code...
Knowing shading language and using it in POV-Ray makes transition to
real-production programs (such as RenderMan, BMRT, RenderDotC) a little
bit easier if someone wants to move from POV-Ray to professional CGI
world. RenderMan interface is flexible, powerful and (unofficial)
standard in CGI.
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Vahur Krouverk wrote:
> I really hope, that this patch is useful for someone and not very much
> of bugs is left there...
Duh, there are bugs and nasty ones, which will crash POV-Ray ;-(
I've updated Windows binaries and source code to avoid this. So, if
someone has problems with POV-Ray crashing during rerendering, when in
previous render shader parameters were incorrectly specified, then fixed
version is available. Linux version will be updated soon. Sorry about
this.
Additionally I've noted, that shader loading and calling counters are
not reset between renderings, but hopefully this is not a problem for
now.
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Pabs wrote:
>
> Vahur Krouverk wrote:
>
> > You read documentation, didn't You?
>
> Obviously not well enough :)
I thought, that there is problem in documentation: my English is not
good enough and documentation could be understood incorrectly...
> Perhaps you could have a system similar to photon mapping where you can ask POV
> to compile the shader (call povslc) to a file if it has not been compiled
> previously.
This automatic compilation would be nice addition, but probably not
trivial one. But I think about it.
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Vahur Krouverk wrote:
> Pabs wrote:
> > Vahur Krouverk wrote:
> > > You read documentation, didn't You?
> >Obviously not well enough :)
> I thought, that there is problem in documentation: my English is not
> good enough and documentation could be understood incorrectly...
I only skimmed the docs - after looking properly at them they were easily
understandable.
-
Bye
Pabs
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