3d graphics can't be saved to a file

[williamstein]

The bug is described below. To fix this and close this ticket, just slightly refactor the code in sage/sage/plot/plot3d/base.pyx so that save to png on a 3d image saves the tachyon rendered file, gives an sobj on an sobj or no extension, and gives an error on all other extension. This will be all one gets initially.

Another later ticket should -- if possible -- make it possible to get the static image from jmol (if possible).

On Thu, Apr 10, 2008 at 11:42 AM, Hector Villafuerte wrote:
> 
>  Hi,
>  I noticed the following (inconsistent?) behavior: saving 2D plots
>  works as expected (a graphic file is stored), but saving 3D plots
>  gives .sobj files instead (see sample code below). Is there a way to
>  save 3D plots from the Notebook? By the way, I know how to save them
>  using jMol's GUI (as reached from Sage terminal), but the idea is to
>  be able to script this.
>

This is a bug.  There's currently no easy nice way to script
saving 3d graphics using Tachyon.   If you do the following

  sage: p = point3d([(k,k^2,0) for k in [0..10]], size=5, viewer='tachyon')
  sage: p.show(filename='a', viewer='tachyon')

then the file a.png will be produced but unfortunately a browser window
will also appear showing this file.


>  --
>   Hector
>  
>  
>  sage: p = point([(k,k^2) for k in [0..10]])
>  sage: p.save(DATA+'plot2d.png')
>  sage: type(p)
>  <class 'sage.plot.plot.Graphics'>
>  
>  sage: p = point3d([(k,k^2,0) for k in [0..10]], size=5)
>  sage: p.save(DATA+'plot3d-1.png')
>  sage: type(p)
>  <class 'sage.plot.plot3d.base.Graphics3dGroup'>
>  
>  sage: p = point3d([(k,k^2,0) for k in [0..10]], size=5, viewer='tachyon')
>  sage: p.save(DATA+'plot3d-2.png')
>  sage: type(p)
>  <class 'sage.plot.plot3d.base.Graphics3dGroup'>

Depends on #8235. 

Component: graphics

Author: Bill Cauchois

Reviewer: Tim Dumol, Robert Bradshaw

Merged: sage-4.3.3.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/2872

[williamstein]

comment:1

Another nice description of the problem by Jason Grout:

This has come up before---p.save() for 2d graphics tries
to save an image.  p.save() for 3d graphics doesn't try to save an
image.  It's an inconsistency.  One way to get fix this is to override
the 3d graphics save routine to do what the 2d graphics save routine
does---look at the file extension and if it is a recognized image
extension, save the image; otherwise, save a Sage sobj pickle.  This is
also why 3d things don't work with animate().  animate() expects to be
able to do p.save('test.png') and have a graphic image test.png saved
out to disk.

You can save a 3d graphics by hand by plotting in jmol and either
selecting "Get Image" next to the image, which converts to jpg, or if
you're doing this from the command line, you can select File|Export from
the java viewer that pops up.  That's rather laborious for creating an
animation, though.

To get an image using tachyon, use show() with filename and viewer
parameters:

sage: show(sphere(), filename='test',viewer='tachyon')

You can use that trick to make a .save() method for 3d graphics (maybe
TransformGroup class or something?) that behaves like the 2d graphics
save.  Then animate should work.

I don't have time to do this right now, but I think this should give
someone enough information to be able to fix things if they are interested.

Thanks,

[sagetrac-wcauchois]

comment:2

The attached patch implements this feature as described. When a filename ending in an image format extension is passed to save (several formats are supported through PIL), Tachyon is used to render the Graphics3d.

I had to factor some code out of show() into _process_viewing_options(), but hopefully that won't break anything (and I think it makes show() much cleaner).

I think this is ready for review.

[TimDumol]

Author: Bill Cauchois

[TimDumol]

comment:3

Works perfectly, but it may be worth adding a short docstring for _process_viewing_options() for developers. Also, PIL supports JPEG, so perhaps that should be added as well. '.tif' should also be accepted. It may be worth nothing that PIL requires libjpeg and libtiff to be present when compiled in order to support JPEG and TIFF.

[TimDumol]

Reviewer: Tim Dumol

[sagetrac-wcauchois]

Attachment: trac_2872.patch.gz

based on sage 4.3.1.rc0