Re: Yet Another Plotting System for Octave: 0.3.0

[Shai Ayal]

On 10/6/07, Alexander Barth <address@hidden> wrote:
> On 10/6/07, Søren Hauberg <address@hidden> wrote:
> > Alexander Barth skrev:
> > > I released version 0.3.0 of yapso. It is available at
> > > http://yapso.sourceforge.net/
> > >
> > > and some demos are at:
> > > http://yapso.sourceforge.net/demo/demo.html
> > This is looking quite nice. I'm curious about two things:
> >
> > 1) Does this work with the Octave graphics objects? I mean, do you use
> > the same graphics structures as the gnuplot backend? Sorry about being
> > so vague, but I don't know much about the graphics stuff in Octave.
> No, it does not use graphics objects code in octave. I'm not very
> familiar with its development. I use a simpler approach, some thing
> like:
>
> class YLine {
>   double MarkerSize;
>
>  virtual octave_value get(string prop) {
>    if (prop == "markersize")
>      return octave_value(MarkerSize);
>   else if...
>   else
>      // call get of base class
>  }
> }
>
> DEFFUN_DLD(get,...) {
>   return object->get(prop);
> }
>
>
> >
> > 2) How do you create postscript output? The png output looks good, but I
> > understand that the other alternative graphics systems have problems
> > with producing high-quality postscript output.
>
> I use gl2ps. I don't use the eps export much, but I worked fine for
> the examples I tried.
> Alex

This is basically what is used by all OpenGL systems -- octplot &
jhandles included. It is a highly non-trivial taks to "render" 3D
OpenGL in postscript, and gl2ps is the best tool to do it. All the
problems actually stem from OpenGL, not the conversion to ps. As I
noted elsewhere, using OpenGL & gl2ps will give OK results, but not
100% professional -- e.g. lines will not always join nicely, and some
numerical glitches may be noticeable -- OpenGL uses no more than
floats to do all it's calculations. This is most noticeable in 2D
plots, less so in 3D plots.
However, all that being said, the ps results are quite nice, and are
truely resolution independant vector graphics.

Shai