Re: POV-Ray Terminal

[Timothée L. <tim...@lp...>]

Ethan Merritt a écrit :
> On Wednesday 27 February 2008 01:17, Timothée Lecomte wrote:
>
>   
>> The authors have bypassed gnuplot terminal system almost completely,
>> and only 'splot' seems to be possible.
>>     
>
> To be fair, it is not clear what one should do with a 'plot' command.
> There are only 2 coordinates, not 3, and we don't have 3D equivalents
> for plot elements like boxes and filledcurves.  The best approach 
> might be to run off a 2D plot as a PNG image, and then map the result
> into 3D using 'splot ... with image'.
>
> 	Ethan
>   

Spreadsheet software usually offer a 3D view of any diagram, applying a 
depth to every single part of the plot, apart from text maybe. A 'plot' 
command on a 3D-"aware" terminal could produce such a thing. I don't 
think it's very useful for complex scientific data, but simple 
histograms look a little more appealing that way.

Best regards,

Timothée

>
>
>   
>> Daniel Farrell a écrit :
>>     
>>> Hello,
>>>
>>> I was listing to the latest FLOSS Weekly Podcast (http://twit.tv/ 
>>> floss24) in which the topic was POV-Ray; an open source ray tracing  
>>> program. After some idle surfing I found that somebody has contributed  
>>> patches to gnuplot for a POV-Ray terminal; fancy ray-traced figures  
>>> found here, (http://t-kita.net/gnuplot_povrml/) and the submitted  
>>> patch here, (http://sourceforge.net/tracker/index.php?func=detail&aid=1262281&group_id=2055&atid=302055 
>>> ).
>>>
>>> I cannot apply this patch successfully to the gnuplot-4.0.0 source? I  
>>> am going like this,
>>>
>>> cp -r gnuplot-4.0.0 gnuplot
>>> cp -r gnuplot gnuplot-patch
>>> mv povray.diff gnuplot
>>> cd gnuplot
>>> patch -p1 < povray.diff
>>>
>>> Anybody have gnuplot and POV-Ray working together?
>>>
>>> Cheers,
>>>
>>> Dan.
>>>
>>>
>>>   
>>>       
>> Hi Daniel,
>>
>> You have found a wonderful peace of work there ! The povray figures that 
>> are given in http://t-kita.net/gnuplot_povrml/ are simply gorgeous. The 
>> two authors, KITA Toshihiro and MIYATA Shigeo, have done something that 
>> others (I included) have probably dreamed of sometimes : let the 
>> terminal driver handle 3D instead of letting gnuplot core do all the 
>> work. Here POV-ray gives a very valuable addition compared to gnuplot 3D 
>> routines : it does true (isometric) perspective, plus realistic shading, 
>> something that is desperately lacking in gnuplot today. There is a patch 
>> on SF.net for adding perspective to gnuplot 3D routines, but the author 
>> did not work on it until inclusion in CVS, and as far as shading (or, 
>> plot points as little spheres, etc), I had never seen such a thing for 
>> gnuplot.
>>
>> There's at least one thing that this work has not achieved according to 
>> the figures : it's pm3d coloring, which is very important for 3d data 
>> visualization. Perspective + shading + pm3d coloring of surfaces plots 
>> would be a great achievement. Let me add that POV-ray, like openGL, is 
>> probably able to draw polygons colored with gradients, something that is 
>> very difficult or impossible with most 2D drawing API (Cairo, for 
>> example, cannot do it). Gradients coloring makes surface plots much 
>> nicer, and gnuplot already has the mechanisms to do that, but they are 
>> used by a single terminal driver, namely the SVGA one, the one that 
>> Ethan never achieved to see working, the one that is also presumably 
>> unsecure. Too bad, isn't it ?
>>
>> Let's talk about the code now.
>> You mention the following patch : 
>> http://sourceforge.net/tracker/index.php?func=detail&aid=1262281&group_id=2055&atid=302055 
>> . This is not the patch that gave the POV-ray figures. This patch on 
>> SF.net only does 2D rendering, as the author, Gaël Varoquaux, explains 
>> on the page:
>>     
>>> This patch is not terribly iseful as long as the 2D/3D code
>>> in gnuplot is not refactored. This patch only implements the
>>> 2D drawing API (as there is no 3D API currently).
>>>       
>> However, the right patch is provided in 
>> http://t-kita.net/gnuplot_povrml/gnuplot_povrml-0.3.patch
>> First, it is offered as a public domain work, so there is no license 
>> issue. Good.
>> It's not really large:
>>     
>>> # diffstat gnuplot_povrml-0.3.patch
>>>  src/plot2d.c    |   21 ++
>>>  src/plot3d.c    |   19 +
>>>  src/povray.c    |  538 
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>  src/term.h      |    6
>>>  src/vrml.c      |  399 +++++++++++++++++++++++++++++++++++++++++
>>>  term/povray.trm |  152 +++++++++++++++
>>>  term/vrml.trm   |  151 +++++++++++++++
>>>  7 files changed, 1286 insertions(+)
>>>       
>> However, after a quick glance at the patch, it's not in a state that 
>> would allow it to be included immediately. The authors have bypassed 
>> gnuplot terminal system almost completely, and only 'splot' seems to be 
>> possible.
>>
>> Steps to make that patch better :
>> - make it work with gnuplot CVS,
>> - identify key functions to design an API to extend the current terminal 
>> one in gnuplot.
>> - get full 2D + 3D (maybe mix this patch with Gaël's one)
>>
>> Thanks Daniel for making this work known !
>> Best regards,
>>
>> Timothée Lecomte
>>     
>
>