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> Would it be possible to parse and render a mixed format scene, for example,
> an XML scene that makes use of existing POV-script include files?
Yes, I think this would be a useful, desirable and
feasible objective. Vice versa as well. It does
imply some shared state information between the
pov-script parser and XML glue to POV, such as
symbol table - but having this in a well defined
module would also be beneficial in other ways.
--
Nigel Stewart (nig### [at] nigels com)
Research Student, Software Developer
Y2K is the new millenium for the mathematically challenged.
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http://www-4.ibm.com/software/developer/library/xml-perl/
Tutorial: XML and scripting languages
Manipulating XML documents with Perl and other scripting languages
Parand Tony Daruger
Co-founder, Binary Evolution, Inc.
February 2000
In this first tutorial of his series on using scripting languages to
manipulate and transform XML documents, Binary Evolution's Parand
Tony Daruger takes you through the first steps of using these
techniques with Perl. You'll see a method for transforming XML
to HTML, followed by a simple stock trading application that uses
Perl, XML, and a database to evaluate trading rules. You can apply
the techniques using other scripting languages too, including Tcl
and Python.
--
Nigel Stewart (nig### [at] nigelscom)
Research Student, Software Developer
Y2K is the new millenium for the mathematically challenged.
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Bruce,
Thanks for your post, forgive me for not giving it proper
attention, but certainly I'll bite on major points.
> I'm only playing a little bit of Devil's advocate here, and that's
> not meant to derail your concept, but an attempt to understand
> what the benefits are. So on with the games <g>
That's fine.
> Ummm... With the complete source code to the EXACT POV parser
> available,
Which BTW is quite hard to maintain, and can't be incorporated
into a commercial tool because of the POV license. This means
that only POV can read POV files.
> but I suspect your purpose
> is not to be able to quickly make money off the honest efforts of
> other's.
I don't have the attitude that commercial application of open
projects is a bad thing. Linux, X Windows, Gimp or KDE have not
suffered because they've been "ripped off" by companies like
Red Hat, IBM, SGI, etc... In fact, these companies are investing
nice things into the core technology, besides making their money.
My interest here is non-commercial, although I could use it
commercially, if the license was more generous.
At the end of the day, I want funkier tools, not tools that
I own and control. I don't care about owning POV - I wouldn't
even care if I'd invested 1000 hours of my time into it. But
that's me, not the POV team.
> My only comment is "just because it uses the modernized Greek alphabet,
> doesn't make it 'human legible'!
It certainly isn't meant to be hand edited, which is an assumption
that many pov users here have a hard time suspending.
> Ask yourself when the last time was that while reading a
> book you ran across the <aTag> ... </aTag> construct?
Very often actually, but in all the parsers I maintain commercially,
they are formulated in different, inconsistent ways.
> HTML and VRML are horrible languages to parse! They include all sorts of
> forward referencing, allow limitless addition of application-specific
> tags
They are still easier to parse than POV, and are at least standardised
so I can buy a commercial library that can handle the VRML parsing for
me. XML I think is easier to parse because it is more constrained than
HTML or VRML.
>(God forbid you accidentally choose the same 'tag-name' as someone
> else)
This is the whole point of XML. You define the tags that are relevant
to your problem domain, specify this to the XML parser, and the rest
is mainly automatic.
> a large number of other inconsistencies, and are far from being
> 'human legible'!
VRML is far more legible than say, 3ds or lightwave. In some ways
comparibly legible to POV-script, considering the difference
between the architectures.
> So basically, I'm wondering what benefit this would really provide?
A means of properly exchanging 3D data between POV ray, 3rd party
tools, database systems, and your own applications. A standardised
means of encoding POV scenes that can be more easily translated
to later versions of POV. A encoding scheme that is more oriented
to editing tools, because the structure is more explicit.
> I fully endorse the POV-teams wish that POV NOT be a library. It is
> completely user supported, out of the sheer goodness-of-heart of a VERY
> few people, and to turn it into a library would open the door for
> unscrupulous people to use it in their own commercial products.
I respect the right of the POV team to do things this way - but
I honestly think it's time for POV to evolve to a rendering
architecture, rather than a rendering application. It's a two
way street with commercial products, you can't expect anything
back in POV if you shut out the professional 3D graphics
community.
> So. To convert the POV language to make it easier to use for people who
> want to make POV tools, seems like a bit of wasted effort, since the
> language parser is already available in source code.
It's not. It is restricted by licenses, and the interface to
POV is not well defined. I've not heard of anyone using the
existing parser this way.
> but does make the get-rich dweebs look
> for another approach.
?!? Have you had some kind of nasty experience !?!
> I've heard the "This is the newest-greatest-bestest language ever"
Me too, but I think XML is a very interesting and useful technology.
> XML may actually provide useful, but it ain't pretty! And it's a long
> way away from human legible.
It's not even meant for human editing in most cases, but since
POV users are so used to hand editing, it may be too tough a
case to make that other methods may have different strengths
and weaknesses.
> So tell me, what benefit would this actually provide?
There is quite a good list on this thread for you to ponder.
(Hope I don't sound too blunt, I'm in a hurry!)
--
Nigel Stewart (nig### [at] nigelscom)
Research Student, Software Developer
Y2K is the new millenium for the mathematically challenged.
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On Wed, 22 Mar 2000 00:58:48 +1100, Nigel Stewart wrote:
>> Ummm... With the complete source code to the EXACT POV parser
>> available,
>
>Which BTW is quite hard to maintain, and can't be incorporated
>into a commercial tool because of the POV license. This means
>that only POV can read POV files.
The POV parser code isn't that hard to maintain. Certainly no harder
than any other recursive-descent parser, perhaps a little easier
than most due to the useful macros.
There's a very well-done POV-to-RIB converter out there somewhere,
using an independently developed parser that happens to be freely
available, I think under the LGPL.
>> My only comment is "just because it uses the modernized Greek alphabet,
>> doesn't make it 'human legible'!
>
>It certainly isn't meant to be hand edited, which is an assumption
>that many pov users here have a hard time suspending.
That's because hand editing (or automatic generation, in some rare cases)
is the only way to make useful scene files. All modelers suck, to one extent
or another.
>> So. To convert the POV language to make it easier to use for people who
>> want to make POV tools, seems like a bit of wasted effort, since the
>> language parser is already available in source code.
>
>It's not. It is restricted by licenses, and the interface to
>POV is not well defined. I've not heard of anyone using the
>existing parser this way.
It is restricted by licenses, but the interface is indeed well-defined. The
definition just happens to be in the form of C source code. But you're right,
nobody is using the existing parser that way, because it's not allowed. Go
reread Chris Young's comments on parsers and the future if you want to know
what the POV-Team thinks should be done about that.
--
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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Bruce wrote:
> Where would I find these comments from Chris Young?
povray.announce.frequently-asked-questions -> plans for 1999 and beyond
--
Ken Tyler - 1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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Ken wrote:
correction -> plans for 3.1 and beyond
--
Ken Tyler - 1300+ 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, 21 Mar 2000 12:13:47 -0800, Bruce wrote:
><g> And just for a bit of a teaser, I am looking very seriously at using
>the POV parser in just this way! It means the end product will have to
>be completely open source, and fall squarely within the limitations of
>the POV license, but I hope it will be useful to POV user's, and perhaps
>garner some support and customization from the current user base.
Better check again before you get too far into that...
A "custom version" is defined as a fully functional version of POV-
Ray with all existing features intact. ANY OTHER USE OF ANY POV-
Ray SOURCE CODE IS EXPRESSLY PROHIBITED. The POV-Team does not
license source code for any use outside POV-Ray. No portion of the
POV-Ray source code may be incorporated into another program
unless it is clearly a custom version of POV-Ray that includes all
of the basic functions of POV-Ray.
--
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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On Tue, 21 Mar 2000 12:17:25 -0800, Bruce wrote:
>> It is restricted by licenses, but the interface is indeed well-defined. The
>> definition just happens to be in the form of C source code. But you're right,
>> nobody is using the existing parser that way, because it's not allowed. Go
>> reread Chris Young's comments on parsers and the future if you want to know
>> what the POV-Team thinks should be done about that.
>>
>
>Oh oh. Would it not be allowed if the resulting product was completely
>open source? Perhaps with documentation/licensing information stating
>that it fell under the general POV license?
I'm pretty sure that the only way to get a different set of terms on the
use of the source code is to get specific permission from the POV Team, but
I'm also pretty sure they/we won't give it lightly. You might find that
ParPov, at http://www9.informatik.uni-erlangen.de/~cnvogelg/pov2rib/ , is
a better choice for your project.
--
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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Bruce wrote:
>
> > > Where would I find these comments from Chris Young?
> >
> > povray.announce.frequently-asked-questions -> plans for 1999 and beyond
>
> Well now that's weird. No matter what I do, I can't get netscape to
> display that news group. I'm assuming this is on the news.povray.org
> server? Just as a side comment, I don't notice the OT group either.
> Something stupid I'm doing? I'm using Netscape 3.01, and setting the
> view options to 'display all groups', yet no such animal.
>
> Bruce
I am not sure why that is happening but I assure you the groups exist.
You might try adding the faq group by visiting this page and clicking
on the active link for that group. It might automatically append itself
to your groups list for this server (maybe). We don't have the off-
topic group in that list so this method won't work to add that group.
http://www.povray.org/groups.html
If you want I can foreward that article in question to you.
--
Ken Tyler - 1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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Bruce wrote:
> (Never ceases to amaze me how helpful people are in the POV newsgroups -
> you would think they would tire of providing the same answer after the
> 20 or 30th time <g>)
As Alan Kong is quick to point out on occasion these groups exist
first and foremost to offer customer supprot for users of the program.
I think they do so quite well.
--
Ken Tyler - 1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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