3D output from gnuplot?
Grant Edwards
It's much easier to understand the data if you can smoothly
rotate the image around, so I've written a Python program that
slowly spins the image.
It might be nice to have some "terminal" choices that produce
3D output instead of 2D projections. What I was thinking about
was maybe having gnuplot produce OOGL format output files,
which could then be displayed by geomview. I think Mathmatica
and Maple both have options to use geomview as an output
device.
Unfortunately, geomview seems to have stagnated and the last
time I tried to build it, it wouldn't even compile with a
modern version of g++.
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Ethan Merritt
Grant Edwards <gra...@visi.com> wrote:
>I've been using gnuplot to plot surfaces and x,y,z data points.
>It's much easier to understand the data if you can smoothly
>rotate the image around, so I've written a Python program that
>slowly spins the image.
Umm. You do know that you can spin a 3D plot in gnuplot
by dragging with the mouse, right?
Or are you just complaining that the motion isn't smooth
enough? As for scripts, no need to go to an external one
in Python, you can do it in gnuplot itself
(see the animation demo).
--
Ethan A Merritt
Grant Edwards
>>I've been using gnuplot to plot surfaces and x,y,z data points.
>>It's much easier to understand the data if you can smoothly
>>rotate the image around, so I've written a Python program that
>>slowly spins the image.
>
> Umm. You do know that you can spin a 3D plot in gnuplot
> by dragging with the mouse, right?
Umm, no, I didn't. I'm pretty sure that the version of Gnuplot
distributed with most Linux distro's doesn't have that feature.
I just built 4.0 today in order to try to get good EMF output,
and haven't had a chance to play with it much.
> Or are you just complaining that the motion isn't smooth
> enough?
The motion is fine. Perhaps it's changed in 4.0, but in 3.7,
there wasn't much in the way of controls for lighting, surface
textures, alpha of materials, etc.
> As for scripts, no need to go to an external one in Python,
> you can do it in gnuplot itself (see the animation demo).
The Python program already existed (it does curve/surface
fitting, and performs some other numerical stuff), so doing the
animation in Python was only another half-dozen lines of code.
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Hans-Bernhard Broeker
> I've been using gnuplot to plot surfaces and x,y,z data points.
> It's much easier to understand the data if you can smoothly
> rotate the image around, so I've written a Python program that
> slowly spins the image.
Another projected now wasted, as all major GUI terminals now support
mouse-driven rotation of 3D plots directly in gnuplot ;-)
The idea of having a native 3D output driver has arisen before, and
there even was a patch that added an OpenGL driver to gnuplot, and
also a VRML one. But ultimately, the problem is that these can't
really be "terminal drivers" in the current internal structure of
gnuplot. By the time data arrive at the terminal driver layer,
they're already in 2D. So a 3D terminal layer would require
a major renovation of large parts of the source code.
If you feel like embarking on a project like this, now is the time.
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Hans-Bernhard Broeker (bro...@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.
Grant Edwards
>> I've been using gnuplot to plot surfaces and x,y,z data points.
>> It's much easier to understand the data if you can smoothly
>> rotate the image around, so I've written a Python program that
>> slowly spins the image.
>
> Another projected now wasted, as all major GUI terminals now support
> mouse-driven rotation of 3D plots directly in gnuplot ;-)
A very cool feature, BTW.
It's not really wasted, since it's still nice to have it spin
by itself, and my code optionally creates an mpeg movie file.
> The idea of having a native 3D output driver has arisen
> before, and there even was a patch that added an OpenGL driver
> to gnuplot, and also a VRML one. But ultimately, the problem
> is that these can't really be "terminal drivers" in the
> current internal structure of gnuplot. By the time data
> arrive at the terminal driver layer, they're already in 2D.
I thought that might be the case.
So when I rotate a surface plot using the mouse in an X window,
the X terminal driver isn't doing the rotation it's requesting
replots from the main program with changed views?
> So a 3D terminal layer would require a major renovation of
> large parts of the source code.
>
> If you feel like embarking on a project like this, now is the
> time.
Sound like a bit more that I have time for.
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Hans-Bernhard Broeker
> So when I rotate a surface plot using the mouse in an X window,
> the X terminal driver isn't doing the rotation it's requesting
> replots from the main program with changed views?
Exactly. If you turn on verbose mode in the mouse interface (hotkey
'6', IIRC), you can even see it do that.