visualpython-users

[Visualpython-users] Vpython and Wiimote

[Martin M. <pro...@gm...>]

A few weeks ago folks posted about using the Wiimote to control vpython.  I
finally got around to posting some video of this on my site.  In short I
used two of the accelerometer axis to control the rotation of the image and
the inclination of the remote to control the zoom.  It is a pretty neat way
to manipulate an image.  Details of how to do this and videos are posted at
my site:
http://profmason.com/?p=529I finally got approval to do a vpython workshop
out at Mt. Sac (As part of a larger workshop on Project based learning)  If
anyone is in the LA area and willing, I would love to find some folks to
come in and talk about how they use Vpython in their classroom.  (Or if you
want to learn how Vpython can be used for integrated projects in the
introductory engineering physics course) The workshop is scheduled from June
14th to the 17th.  Contact me for more info at pro...@gm...

have fun!
Martin Mason
---------------------
Martin S. Mason
Professor of Physics
Mt. San Antonio College
1100 N. Grand Ave.
Walnut, CA 91789

Re: [Visualpython-users] Creating .png files in Linux

[<fre...@gb...>]

On mardi 15 janvier 2008, Bruce Sherwood wrote:

> The URL you give is not valid.

There is just a missing dot just before 'avi'... Sorry!

> Can you please explain the heart of your program, the function
> generateMovie? I don't understand what is involved in combining many png
> images into a movie. What is the format of the movie? How does one view
> such a movie?
>
> Also, I don't see where/how the povexport facility is invoked (povexport
> is a routine available on the home page of vpython.org). Maybe it's
> buried inside the module "Scene3D" which you don't include?

Ok. The povexport.pov() function is called in the scene.pov() method. It=20
generates the pov file with the given filename of the current scene. But=20
this method is call through __povexport(), which also call povray to=20
generate the png image.

The idea is to define some points where we go in straight line. This is=20
done in the move() method. By points I mean 2 things: the spectrometer=20
position, and the camera position (for zooms). All this is given in the=20
mvt dict. Most of keys are send to sub-objects, and are just angles of=20
differents spectro parts.

At each step in the move(), we call the draw method, which in turn refresh=
=20
all sub-objects and also generate a png image.

There is also a wait() method, which just to generate images at the same=20
position, with respect of the timing.

Last, there is a neutron object which can move along a pre-defined line,=20
and which also call the __povexport() method (through its newFrameSignal()=
=20
object, binded to that method).

At the end, we have all png images. The generateMove() method build a movie=
=20
from that, using mplayer (Don't ask me for all options; a friend gave them=
=20
to me!).

Hope this helps. Feel free to ask for more informations.

=2D-=20
   Fr=E9d=E9ric

   http://www.gbiloba.org

Re: [Visualpython-users] Creating .png files in Linux

[Bruce S. <Bru...@nc...>]

The URL you give is not valid.

Can you please explain the heart of your program, the function 
generateMovie? I don't understand what is involved in combining many png 
images into a movie. What is the format of the movie? How does one view 
such a movie?

Also, I don't see where/how the povexport facility is invoked (povexport 
is a routine available on the home page of vpython.org). Maybe it's 
buried inside the module "Scene3D" which you don't include?

Bruce Sherwood

Frédéric wrote:
> Le 14/1/2008, "Lorenzo Isella" <lor...@gm...> a écrit:
> 
> 
>>I am stepping back from my previous post, when I was asking how to
>>make a movie in vpython.
>>That was too ambitious then.
>>I managed to get some decent animations on my laptop (running Debian
>>testing); now my question is how to get at least a set of png (or any
>>other decent format; pdf, eps, jpg etc...) files with the "snapshots"
>>of my system.
>>I do not think I can do that directly from the window showing my
>>animation, but I have not been able to find online a code showing how
>>to achieve that.
> 
> 
> Why don't you use povexport? You generate .pov files, and you  can then
> process them by a simple script, and build the movie.
> 
> I attached a script I've done 3 years ago, for a student in order to
> generate this:
> 
>     http://www.gbiloba.org/download/SNP-definitif-640x480avi
> 
> 
> --
>    Frédéric

[Visualpython-users] VPython to Video

[Joel K. <jj...@ya...>]

The good news is, I have been able to get
fair-to-decent results grabbing VPython
animations to video using CamStudio:

http://camstudio.org/

The bad news is, the program exists only
in Windows, and I don't know of anyone
working on a Linux port yet. The license 
is GNU GPL, so there shouldn't be any
problems if someone wants to jump in.
Maybe one of you computer science teachers
out there would like to offer class credit
to some hot-shot students willing to try?

Joel



      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs

Re: [Visualpython-users] Creating .png files in Linux

[<fre...@gb...>]

Le 14/1/2008, "Lorenzo Isella" <lor...@gm...> a =E9crit:

>I am stepping back from my previous post, when I was asking how to
>make a movie in vpython.
>That was too ambitious then.
>I managed to get some decent animations on my laptop (running Debian
>testing); now my question is how to get at least a set of png (or any
>other decent format; pdf, eps, jpg etc...) files with the "snapshots"
>of my system.
>I do not think I can do that directly from the window showing my
>animation, but I have not been able to find online a code showing how
>to achieve that.

Why don't you use povexport? You generate .pov files, and you  can then
process them by a simple script, and build the movie.

I attached a script I've done 3 years ago, for a student in order to
generate this:

    http://www.gbiloba.org/download/SNP-definitif-640x480avi


--
   Fr=E9d=E9ric

Re: [Visualpython-users] Creating .png files in Linux

[Kadir H. <kha...@ya...>]

Lorenzo Isella wrote:

> I 
managed 
to 
get 
some 
decent 
animations 
on 
my 
laptop 
(running 
Debian
> testing); 
now 
my 
question 
is 
how 
to 
get 
at 
least 
a 
set 
of 
png 
(or 
any
> other 
decent 
format; 
pdf, 
eps, 
jpg 
etc...) 
files 
with 
the 
"snapshots"
> of 
my 
system.

I can answer your question for Windows environment. Same or similar solution MAY or 
MAY NOT apply for Linux, I have no experience in Linux environment.

First you need to install Python Image Library, PIL, if you have not done so
already. You may be using it already, if you are using TEXTURE feature of
the recent Beta versions of VPython.

Then in your source code you need to add some lines, like the followings:

import Image
import ImageGrab
...

Your animation code goes here

...

while looping:

        im = ImageGrab.grab((24,30,ImageWidth-4,ImageHeight-4))
        fn = "Cat"+str(pn)+".png"
        im.save(fn)

fn is the filename in Windows environment. 

IF THIS SYSTEM WORKS in LINUX, then someting similar to that of filename should be sufficient.
ImageGrab needs the display location (upper-left corner) and display sizedefined to it, so it picks up
the image from the screen for you.

You need to set up some sort of a counter in the loop like the str(pn), to get a unique
file name for each snapshot.

Hope it works...

Kadir





      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs

[Visualpython-users] Creating .png files in Linux

[Lorenzo I. <lor...@gm...>]

Hello,
I am stepping back from my previous post, when I was asking how to
make a movie in vpython.
That was too ambitious then.
I managed to get some decent animations on my laptop (running Debian
testing); now my question is how to get at least a set of png (or any
other decent format; pdf, eps, jpg etc...) files with the "snapshots"
of my system.
I do not think I can do that directly from the window showing my
animation, but I have not been able to find online a code showing how
to achieve that.
Any help here is really welcome!
Many thanks

Lorenzo

[Visualpython-users] 4.beta24

[Bruce S. <Bru...@nc...>]

Chipping away at the beta version, there is a new 4.beta24 for Windows 
and Linux.

For the new points object, remove the "antialias" attribute and create a 
shape attribute (currently "round" or "square"). Updated the summary of 
the features in the beta version. Added mandelbrot.py to examples, to 
show how to do pixel-oriented graphing. Fixed a bug which prevented 
specifying a color array in a curve or points constructor.

Bruce Sherwood

[Visualpython-users] platform specific messages

[P H B. <p.h...@bh...>]

Dear visualpython-users

Some Vpython emails are specific to a particular platform (linux  mac 
windows etc) and are of minimal interest to those using another platform.

 It would be helpful, particularly to users of other platforms, if those 
generating such emails were to include the platform name in the subject line

Regards

Peter

Re: [Visualpython-users] VSpace.py Demo

[Ron A. <rr...@ro...>]

Bruce Sherwood wrote:
> There's something wrong with the program you posted:
> 
> Traceback (most recent call last):
>    File "C:\Documents and Settings\Bruce\My Documents\Python 
> stuff\vspace.py", line 279, in -toplevel-
>      ship.animate(period, len(asteroids))
>    File "C:\Documents and Settings\Bruce\My Documents\Python 
> stuff\vspace.py", line 121, in animate
>      self.status.text = 'frame rate = %i, asteroids = %s' \
> ZeroDivisionError: float divmod()

If I change the time.time() calls to time.clock(), I get that too.

I did have the import wrong for the time module.  Since I originally wrote 
this on XP.

Changed:

    from time import clock

to:

    import time

    # use time.clock if it works, else use time.time.
    if time.clock() != time.clock():
        time.time = time.clock


There is differences between time.clock and time.time between linux and 
windows.  I'm using Ubuntu.  The above should fix it.

File attached with corrections.


> Also, I'll note that you have the following:
> 
>      scene.range = (0, 0, 0)
>      scene.scale = (.1, .1, .1)

Thanks, removed the scene.range assignment.


Ron

Re: [Visualpython-users] VSpace.py Demo

[Bruce S. <Bru...@nc...>]

There's something wrong with the program you posted:

Traceback (most recent call last):
   File "C:\Documents and Settings\Bruce\My Documents\Python 
stuff\vspace.py", line 279, in -toplevel-
     ship.animate(period, len(asteroids))
   File "C:\Documents and Settings\Bruce\My Documents\Python 
stuff\vspace.py", line 121, in animate
     self.status.text = 'frame rate = %i, asteroids = %s' \
ZeroDivisionError: float divmod()

Also, I'll note that you have the following:

     scene.range = (0, 0, 0)
     scene.scale = (.1, .1, .1)

The scene.range statement is irrelevant, because the scene.scale 
statement is equivalent to scene.range = (10,10,10). But in the beta 
version setting the range to 0 gives an error, as it should; it's a 
failing in the production version not to give an error.

Bruce Sherwood

Ron Adam wrote:
> 
> I made some changes to the VSpace.py Demo I posted earlier.
> 
> Velocities are now time based instead of frame based, so that things 
> should appear to move at the same speed on different speed computers.
> 
> The frame rate is limited by adding and removing asteroid objects.  So 
> the number of asteroid objects acts as a rough bench mark.  On my system 
> I get 220 asteroids at 60 FPS.  Your mileage may vary of course. ;-)
> 
> Rotation of the world is done all at once by rotating the parent "space" 
> frame instead of rotating frames individually.
> 
> You can zoom in and out of the field of view by pressing both mouse 
> buttons at the same time.  This allows you to see how everything moves 
> relative to the view.  This was disabled before.
> 
> The objects, asteroids, sun, stars, ship, are implemented with classes 
> with an "animate" method.  This groups related code together in a much 
> nicer way.
> 
> 
> Enjoy,
>   Ron Adam

Re: [Visualpython-users] Upgrading to Beta. Trouble compiling glibmm-2.14.0 No file gregex.h

[Bruce S. <Bru...@nc...>]

I would think you'd have to address your question to the glibmm experts, 
not to VPython users....?

As to configure issues, what configure typically does on Linux is check 
for basic resources being available, and in what form. For example, is a 
C++ compiler available, are there libraries available on which glibmm 
depends, etc. A script for configuring the building of glibmm does not 
check that all the glibmm files are present, because a tarball for 
glibmm is supposed to contain all the glibmm files.

Bruce Sherwood

chris lyon wrote:
> I'm having problems compiling glibmm-2.14.0
> it configures ok but upon trying make I get:
> 
> In file included from regex.cc:4:
> ../../glib/glibmm/regex.h:29:25: error: glib/gregex.h: No such file or 
> directory
> ../../glib/glibmm/regex.h:594: error: ‘GRegexEvalCallback’ has not been 
> declared
> 
> ......
> 
> 
> any ideas how this can be happening? My understanding is configure 
> checks for the required bits and pieces before make runs? How do I 
> address this problem?
> 
> Chris
> 

Re: [Visualpython-users] Upgrading to Beta. Trouble compiling glibmm-2.14.0 No file gregex.h

[<fre...@gb...>]

On samedi 12 janvier 2008, chris lyon wrote:

> I'm having problems compiling glibmm-2.14.0
> it configures ok but upon trying make I get:
>
> In file included from regex.cc:4:
> ../../glib/glibmm/regex.h:29:25: error: glib/gregex.h: No such file or
> directory
> ../../glib/glibmm/regex.h:594: error: =E2=80=98GRegexEvalCallback=E2=80=
=99 has not been
> declared
>
> ......
>
>
> any ideas how this can be happening? My understanding is configure
> checks for the required bits and pieces before make runs? How do I
> address this problem?

This header is in the libglib2.0-dev package. Is it installed ?

=2D-=20
   Fr=C3=A9d=C3=A9ric

   http://www.gbiloba.org

Re: [Visualpython-users] Vpython Beta on Fedora

[Jaap S. <j....@hc...>]

Jaap Spies wrote:
> bradley wrote:
>> Jaap,
>>    I had proposed that question before to some people and I was told 
>> that was not it.  This makes me feel a lot better about myself lol.  Do 
>> you happen to know what boost lib file is missing so that I could ask 
>> the boost people what they recommend on doing, and also why the file was 
>> deleted.
> 
> I have to look it up, but I remember there was only a libboost_thread.mt
> on Fedora 8. I'll come back on that later!
> 

On Fedora 8 there is only /usr/libboost_thread-mt.so and family, not
/usr/lib/libboost_thread.so

FC 7: boost-1.33.1
FC 8: boost-1.34.1

So, what's the difference?

Jaap

Re: [Visualpython-users] Vpython Beta on Fedora

[Jaap S. <j....@hc...>]

bradley wrote:
> Jaap,
>    I had proposed that question before to some people and I was told 
> that was not it.  This makes me feel a lot better about myself lol.  Do 
> you happen to know what boost lib file is missing so that I could ask 
> the boost people what they recommend on doing, and also why the file was 
> deleted.

I have to look it up, but I remember there was only a libboost_thread.mt
on Fedora 8. I'll come back on that later!

Jaap



> Brad
> 
> 
> 
> Jaap Spies wrote:
>> bradley wrote:
>>>     I have not been able to get any of the beta version to compile on 
>>> Fedora.  The reason is not a dependency issue, but may have something 
>>> to do with differences between Fedora and Ubuntu.  Or at least that 
>>> was my understanding of it.  Recently I have met up with someone 
>>> though who might have a solution and if so I will be able to make 
>>> some rpm's shortly.  I will post them on my site as usual.     If 
>>> anyone using Fedora 8 has gotten a beta version to compile please let 
>>> me know.
>>>    
>>
>> On Fedora 7 no problem, but on Fedora 8 there is a missing
>> libboost_thread library in boost. The boost version in FC8 is rotten!
>>
>> Jaap
>>
> 
> 
> 

Re: [Visualpython-users] Vpython Beta on Fedora

[Jaap S. <j....@hc...>]

bradley wrote:
>     I have not been able to get any of the beta version to compile on 
> Fedora.  The reason is not a dependency issue, but may have something to 
> do with differences between Fedora and Ubuntu.  Or at least that was my 
> understanding of it.  Recently I have met up with someone though who 
> might have a solution and if so I will be able to make some rpm's 
> shortly.  I will post them on my site as usual. 
>     If anyone using Fedora 8 has gotten a beta version to compile please 
> let me know.
>    

On Fedora 7 no problem, but on Fedora 8 there is a missing
libboost_thread library in boost. The boost version in FC8 is rotten!

Jaap

[Visualpython-users] Vpython Beta on Fedora

[bradley <bj...@nc...>]

    I have not been able to get any of the beta version to compile on 
Fedora.  The reason is not a dependency issue, but may have something to 
do with differences between Fedora and Ubuntu.  Or at least that was my 
understanding of it.  Recently I have met up with someone though who 
might have a solution and if so I will be able to make some rpm's 
shortly.  I will post them on my site as usual. 
    If anyone using Fedora 8 has gotten a beta version to compile please 
let me know.
   
Brad

[Visualpython-users] Upgrading to Beta. Trouble compiling glibmm-2.14.0 No file gregex.h

[chris l. <chr...@sp...>]

I'm having problems compiling glibmm-2.14.0
it configures ok but upon trying make I get:

In file included from regex.cc:4:
../../glib/glibmm/regex.h:29:25: error: glib/gregex.h: No such file or 
directory
../../glib/glibmm/regex.h:594: error: ‘GRegexEvalCallback’ has not been 
declared

......


any ideas how this can be happening? My understanding is configure 
checks for the required bits and pieces before make runs? How do I 
address this problem?

Chris

Re: [Visualpython-users] Background images...

[Bruce S. <Bru...@nc...>]

In the beta version (see "Recent developments" at vpython.org), in the 
example program stonehenge.py you'll see photos of flowers on walls, and 
in the "Contributed programs" section of vpython.org the program 
image.py shows some details about this.

In the production version of VPython there is no way to display an image.

Bruce Sherwood

Frédéric Mantegazza wrote:
> On samedi 12 janvier 2008, jer...@in... wrote:
> 
>> Is there a way of filling the display space of a VP window with some
>> jpeg, or other image?
> 
> What do you mean by filling? With beta version, you can map an image on a 
> surface object (only sphere and plans fomr the moment). Is it what you 
> need?
> 

Re: [Visualpython-users] Generating PDF and Movies in Visual Python

[Bruce S. <Bru...@nc...>]

I suggest you study the VPython example program gas.py, which 
manipulates Numeric arrays without loops, then updates the pos 
attributes of all objects in a very tight loop.

The key point is that you shouldn't be dealing with individual x, y, and 
z lists or arrays but rather with arrays of <x,y,z> vectors.

Bruce Sherwood

P.S. Technical point: The production version of VPython (3.2.9) imports 
Numeric (so you don't have to explicitly import it yourself), and the 
beta version (4.beta) imports numpy.

Lorenzo Isella wrote:
> Hello,
> and thanks for your help.
> Probably I'd better make one step at the time.
> I made some progress in creating an animation; say that I have n_part 
> particles and n_config  stored configurations (i.e.snapshots of the 
> system), and that all the particles coordinates in a given configuration 
> are stored in x_list, y_list, z_list, then this is what I can do:
> 1) read the particle positions from tot_config and plot the initial 
> configuration
> 
>     my_config=0
>     for i in xrange(0,n_part):
> 
> 
>         x_list[i]=tot_config[my_conf,3*i]
>         y_list[i]=tot_config[my_conf,(3*i+1)]
>         z_list[i]=tot_config[my_conf,(3*i+2)]
> 
>   
> 
>     particles=[v.sphere(pos=loc,radius=my_rad,color=v.color.blue)\
>                for loc in zip(x_list,y_list,z_list)] 
> 
> 2) Then I can update the particle positions by reading the other 
> configurations and re-using x_list,y_list and z_list:
> 
>     for my_conf in xrange(1,n_config):
>        
>        
>         for i in xrange(0,n_part):
>                 x_list[i]=tot_config[my_conf,3*i]
>                 y_list[i]=tot_config[my_conf,(3*i+1)]
>                 z_list[i]=tot_config[my_conf,(3*i+2)]
>                 v.rate(1000)
>                 particles[i].pos=(x_list[i],y_list[i],z_list[i])   
> 
> 
> The problem of doing so is that I am "moving" only a particle at the 
> time, it takes quite some time and the resulting animations looks 
> somehow odd.
> My idea would be: first generate the particles and locate them as in the 
> initial configuration, then read the second configuration and move all 
> the particles accordingly in a single go and so on and so forth.
> However, whereas I can directly address e.g. particles[4].pos, I cannot 
> manipulate in one go all the particle positions directly via 
> particles.pos, which is why I am posting again.
> I am sure that fixing this must be a one-liner, but so far I have not 
> achieved much.
> Many thanks
> 
> Lorenzo
> 
> 
> 
>> Message: 3
>> Date: Thu, 10 Jan 2008 17:52:30 -0800
>> From: Scott David Daniels <Sco...@Ac...>
>> Subject: Re: [Visualpython-users] Generating PDF and Movies in Visual
>> 	Python
>> To: vis...@li...
>> Message-ID: <fm6hs4$rhj$1...@ge...>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Lorenzo Isella wrote:
>>   
>>> ...
>>> pos_list=s.zeros(3) # I initialize the array to contain the single 
>>> particle's coordinates
>>> my_rad=1.06/2.
>>> for i in xrange(0,n_part):  #n_part is the number of particles in my system
>>>     pos_list[0]=x_list[i]  #x_list contains a list of the x-coordinate 
>>> of all the particles in the system at a given time
>>>     pos_list[1]=y_list[i]
>>>     pos_list[2]=z_list[i]
>>>     particle=v.sphere(pos=pos_list,radius=my_rad,color=v.color.blue)
>>>     
>>  > In a sense, I have filled the space with the same particle repeated
>>  > many times, whereas I would like to have an array of particles
>>  > part[j] whose positions can be updated in time.
>>
>> Try this (to get all points in the frame):
>>      my_rad = 1.06 / 2.
>>      particles = [v.sphere(pos=loc, radius=my_rad, color=v.color.blue)
>>                   for loc in zip(x_list, y_list, z_list)]
>>
>>   
>>> 1)zooming and selecting a part of the scene (i.e. some specific particle 
>>> configurations) and generating a pdf or eps or jpg or png file.
>>>     
>> See Ruth Chabay's contributed program to go from Vpython to POV-Ray
>> source, then use POV-Ray to go from source to .png image.
>>
>>   
>>> 2)generating a movie. I saw there is a contributed program which should 
>>> work only for MacOS and I wonder if there is anything similar available 
>>> for Linux (I am running Debian testing on my box).
>>>     
>> First, you are not asking anything simple when you ask to go to a movie.
>> Your head needs to get higher if you really want to do this.  E-mail me
>> separately if you have everything solved up through getting .png images,
>> and I can provide you with "no redistribution; no comercial use" code to
>> take a bunch of .png files to a .mng file (which is an obscure movie
>> format, but there _are_ a few readers out there).
>>
>> --Scott David Daniels
>> Sco...@Ac...
>>

Re: [Visualpython-users] Background images...

[<fre...@gb...>]

On samedi 12 janvier 2008, jer...@in... wrote:

> Is there a way of filling the display space of a VP window with some
> jpeg, or other image?

What do you mean by filling? With beta version, you can map an image on a=20
surface object (only sphere and plans fomr the moment). Is it what you=20
need?

=2D-=20
   Fr=E9d=E9ric

   http://www.gbiloba.org

[Visualpython-users] Background images...

[<jer...@in...>]

Gents, I am a "newbie" (with a long beard).
Perhaps I should have read more carefully the docs... 

Is there a way of filling the display space of a VP window with some
jpeg, or other image? 

Thanks.
If the "normal" answer is a plain "no", is it possible to hack the system
routines, i.e. did somebody do that? 


Jerzy Karczmarczuk 

Re: [Visualpython-users] Generating PDF and Movies in Visual Python

[Lorenzo I. <lor...@gm...>]

Hello,
and thanks for your help.
Probably I'd better make one step at the time.
I made some progress in creating an animation; say that I have n_part 
particles and n_config  stored configurations (i.e.snapshots of the 
system), and that all the particles coordinates in a given configuration 
are stored in x_list, y_list, z_list, then this is what I can do:
1) read the particle positions from tot_config and plot the initial 
configuration

    my_config=0
    for i in xrange(0,n_part):


        x_list[i]=tot_config[my_conf,3*i]
        y_list[i]=tot_config[my_conf,(3*i+1)]
        z_list[i]=tot_config[my_conf,(3*i+2)]

  

    particles=[v.sphere(pos=loc,radius=my_rad,color=v.color.blue)\
               for loc in zip(x_list,y_list,z_list)] 

2) Then I can update the particle positions by reading the other 
configurations and re-using x_list,y_list and z_list:

    for my_conf in xrange(1,n_config):
       
       
        for i in xrange(0,n_part):
                x_list[i]=tot_config[my_conf,3*i]
                y_list[i]=tot_config[my_conf,(3*i+1)]
                z_list[i]=tot_config[my_conf,(3*i+2)]
                v.rate(1000)
                particles[i].pos=(x_list[i],y_list[i],z_list[i])   


The problem of doing so is that I am "moving" only a particle at the 
time, it takes quite some time and the resulting animations looks 
somehow odd.
My idea would be: first generate the particles and locate them as in the 
initial configuration, then read the second configuration and move all 
the particles accordingly in a single go and so on and so forth.
However, whereas I can directly address e.g. particles[4].pos, I cannot 
manipulate in one go all the particle positions directly via 
particles.pos, which is why I am posting again.
I am sure that fixing this must be a one-liner, but so far I have not 
achieved much.
Many thanks

Lorenzo



>
> Message: 3
> Date: Thu, 10 Jan 2008 17:52:30 -0800
> From: Scott David Daniels <Sco...@Ac...>
> Subject: Re: [Visualpython-users] Generating PDF and Movies in Visual
> 	Python
> To: vis...@li...
> Message-ID: <fm6hs4$rhj$1...@ge...>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Lorenzo Isella wrote:
>   
>> ...
>> pos_list=s.zeros(3) # I initialize the array to contain the single 
>> particle's coordinates
>> my_rad=1.06/2.
>> for i in xrange(0,n_part):  #n_part is the number of particles in my system
>>     pos_list[0]=x_list[i]  #x_list contains a list of the x-coordinate 
>> of all the particles in the system at a given time
>>     pos_list[1]=y_list[i]
>>     pos_list[2]=z_list[i]
>>     particle=v.sphere(pos=pos_list,radius=my_rad,color=v.color.blue)
>>     
>  > In a sense, I have filled the space with the same particle repeated
>  > many times, whereas I would like to have an array of particles
>  > part[j] whose positions can be updated in time.
>
> Try this (to get all points in the frame):
>      my_rad = 1.06 / 2.
>      particles = [v.sphere(pos=loc, radius=my_rad, color=v.color.blue)
>                   for loc in zip(x_list, y_list, z_list)]
>
>   
>> 1)zooming and selecting a part of the scene (i.e. some specific particle 
>> configurations) and generating a pdf or eps or jpg or png file.
>>     
> See Ruth Chabay's contributed program to go from Vpython to POV-Ray
> source, then use POV-Ray to go from source to .png image.
>
>   
>> 2)generating a movie. I saw there is a contributed program which should 
>> work only for MacOS and I wonder if there is anything similar available 
>> for Linux (I am running Debian testing on my box).
>>     
> First, you are not asking anything simple when you ask to go to a movie.
> Your head needs to get higher if you really want to do this.  E-mail me
> separately if you have everything solved up through getting .png images,
> and I can provide you with "no redistribution; no comercial use" code to
> take a bunch of .png files to a .mng file (which is an obscure movie
> format, but there _are_ a few readers out there).
>
> --Scott David Daniels
> Sco...@Ac...
>
>
>
>
>   

[Visualpython-users] VSpace.py Demo

[Ron A. <rr...@ro...>]

I made some changes to the VSpace.py Demo I posted earlier.

Velocities are now time based instead of frame based, so that things should 
appear to move at the same speed on different speed computers.

The frame rate is limited by adding and removing asteroid objects.  So the 
number of asteroid objects acts as a rough bench mark.  On my system I get 
220 asteroids at 60 FPS.  Your mileage may vary of course. ;-)

Rotation of the world is done all at once by rotating the parent "space" 
frame instead of rotating frames individually.

You can zoom in and out of the field of view by pressing both mouse buttons 
at the same time.  This allows you to see how everything moves relative to 
the view.  This was disabled before.

The objects, asteroids, sun, stars, ship, are implemented with classes with 
an "animate" method.  This groups related code together in a much nicer way.


Enjoy,
   Ron Adam

Re: [Visualpython-users] Generating PDF and Movies in Visual Python

[Kadir H. <kha...@ya...>]

Scott David Daniels wrote:
> ...
> See 
Ruth 
Chabay's 
contributed 
program 
to 
go 
from 
Vpython 
to 
POV-Ray
> source, 
then 
use 
POV-Ray 
to 
go 
from 
source 
to 
.png 
image.

I am not sure if I am missing anything, but in the Windows environment at least, 
you can obtain .png files directly from within Vpython, without going through POV-Ray,
although it gives a much better photo-realistic output (at a very high cost of raster time).

At the moment I am using Windows MovieMaker to make movies from a series of .png
files, which results in very large file sizes with low video quality. I have tried several Divx
Authoring programs with not much success in terms of file size.

I have looked into MNG "movie" format which apparently is not supported in common
video player environments. I have not attempted yet installing all those libs to get the .mng
output done. Do you have any feeling on the .mng file sizes in relation with .png files, and
the output quality?

Kadir Haldenbilen


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