POV-Ray : Newsgroups : povray.unix : povray with stdin Server Time
24 Dec 2024 13:03:20 EST (-0500)
  povray with stdin (Message 1 to 9 of 9)  
From: Peterson
Subject: povray with stdin
Date: 26 Oct 2005 05:05:01
Message: <web.435f45a6a133f8f5c8b148b80@news.povray.org>
Hi all,

I need send scene description to the povray (v. 3.6) via stdin. I read man
pages and there is "+I-", I use this but I get only error, not rendering.

My command:
cat scene.pov | povray +I-

Povray output:
Redirecting Options
  All Streams to console..........On
  Debug Stream to console.........On
  Fatal Stream to console.........On
  Render Stream to console........On
  Statistics Stream to console....On
  Warning Stream to console.......On
Parsing Options
  Input file: stdin (compatible to version 3.61)
  Remove bounds........On
  Split unions.........Off
  Library paths:
    /usr/local/share/povray-3.6
    /usr/local/share/povray-3.6/ini
    /usr/local/share/povray-3.6/include
Output Options
  Image resolution 320 by 240 (rows 1 to 240, columns 1 to 320).
  Output file: /Documents/POVRAY/stdin.png, 24 bpp PNG
  Graphic display......On  (gamma: 2.2)
  Mosaic preview.......Off
  CPU usage histogram..Off
  Continued trace......Off
Tracing Options
  Quality:  9
  Bounding boxes.......On   Bounding threshold: 3
  Light Buffer.........On
  Vista Buffer.........On   Draw Vista Buffer....Off
  Antialiasing.........Off
  Clock value:    0.000  (Animation off)

  0:00:00 Parsing
File: stdin  Line: 1
File Context (5 lines):

Parse Error: Expected 'object or directive', undeclared identifier 'Pty'
found
 instead

When I use command "povray scene.pov" rendering is OK.

Can you help me? Thanks


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From: Sebastian H 
Subject: Re: povray with stdin
Date: 26 Oct 2005 09:56:31
Message: <435f8b0f$1@news.povray.org>
Peterson wrote:
> Hi all,
> 
> I need send scene description to the povray (v. 3.6) via stdin. I read man
> pages and there is "+I-", I use this but I get only error, not rendering.
> 
> My command:
> cat scene.pov | povray +I-
> 

I wanted to suggest to use a fifo this way.

mkfifo myfifo
cat scene.pov > myfifo &
povray +Imyfifo

but it does not work.
Sorry.

Sebastian


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From: Christoph Hormann
Subject: Re: povray with stdin
Date: 26 Oct 2005 10:15:01
Message: <djo2v2$81u$1@chho.imagico.de>
Peterson wrote:
> Hi all,
> 
> I need send scene description to the povray (v. 3.6) via stdin. I read man
> pages and there is "+I-", I use this but I get only error, not rendering.
> 

The man pages are outdated in this point (and have been for a long time).

Scene files are required to be searchable to be parsed.  Therefore you 
can neither use named nor unnamed pipes for them.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 22 Oct. 2005)
MegaPOV with mechanics simulation: http://megapov.inetart.net/


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From: Jan T  Kim
Subject: Re: povray with stdin
Date: 28 Mar 2006 12:15:00
Message: <web.44296e6463025cfb421c4b930@news.povray.org>
Christoph Hormann <chr### [at] gmxde> wrote:
> Peterson wrote:
> > Hi all,
> >
> > I need send scene description to the povray (v. 3.6) via stdin. I read man
> > pages and there is "+I-", I use this but I get only error, not rendering.
> >
>
> The man pages are outdated in this point (and have been for a long time).
>
> Scene files are required to be searchable to be parsed.  Therefore you
> can neither use named nor unnamed pipes for them.

Is there any hope that this restriction will be removed in the not
too distant future? We're planning to put together a pipeline for
generating 3D images using a cgi script, and if possible, I would like
to avoid the messy issue of generating temporary files and cleaning them
up in a way that works robustly in a multiprocess environment (i.e. if
more than one cgi processes execute concurrently).

Is there any explanation on why the file has to be searchable? Normally,
one is much better off using only one's own data structures once having
acquired them by parsing...

Best regards, Jan


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From: Nicolas Calimet
Subject: Re: povray with stdin
Date: 28 Mar 2006 14:29:48
Message: <44298eac$1@news.povray.org>
> Is there any hope that this restriction will be removed in the not
> too distant future?

	Most likely not.

> Is there any explanation on why the file has to be searchable?

	For example: think about POV-Ray macros.

	- NC


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From: Christoph Hormann
Subject: Re: povray with stdin
Date: 28 Mar 2006 14:30:03
Message: <e0c2oc$vri$1@chho.imagico.de>
Jan T. Kim wrote:
>>
>> Scene files are required to be searchable to be parsed.  Therefore you
>> can neither use named nor unnamed pipes for them.
> 
> Is there any hope that this restriction will be removed in the not
> too distant future?

No.  To be more precise: not with the current scene description language.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 14 Mar. 2006)
MegaPOV with mechanics simulation: http://megapov.inetart.net/


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From: Jan T  Kim
Subject: Re: povray with stdin
Date: 30 Mar 2006 11:25:01
Message: <web.442c05ef63025cfb421c4b930@news.povray.org>
Nicolas Calimet <pov### [at] freefr> wrote:
> > Is there any hope that this restriction will be removed in the not
> > too distant future?
>
>  Most likely not.
>
> > Is there any explanation on why the file has to be searchable?
>
>  For example: think about POV-Ray macros.

How do macros necessitate searchable files?

Random access to files can generally be replaced with random access
to the structures obtained by parsing, which are in memory (RAM)
anyway.

Best regards, Jan


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From: Thorsten Froehlich
Subject: Re: povray with stdin
Date: 30 Mar 2006 11:36:43
Message: <442c091b@news.povray.org>
Jan T. Kim wrote:
> How do macros necessitate searchable files?

The short answer: Macros can be self-modifying by writing to files.

Of course, it is far more complex than this.

	Thorsten


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From: Jan T  Kim
Subject: Re: povray with stdin
Date: 30 Mar 2006 12:25:00
Message: <web.442c138b63025cfb421c4b930@news.povray.org>
Thorsten Froehlich <tho### [at] trfde> wrote:
> Jan T. Kim wrote:
> > How do macros necessitate searchable files?
>
> The short answer: Macros can be self-modifying by writing to files.

Ok -- that answer is spot on, modifications to macros in files are
clearly not compatible with the idea of using the data structures
parsed from the file (possibly before modification).

However, would it not be possible to evolve the parser such that it
fseeks only if that is really needed, so that a straightforward scene
that doesn't involve anything fancy such as modifying files etc. can
be parsed from a non-seekable stream?

> Of course, it is far more complex than this.

You're making me curious.

Best regards, Jan


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