[Visualpython-users] Making a Movie in Visual Python

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

Dear All,
Quite some time ago I asked some questions abut how to make a movie in 
Visual Python.
Among the various answers I got, I was trying this suggestion:


On 14/01/2008, Kadir Haldenbilen <kha...@ya...> wrote:
 >
 > 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
 >
 >
 >  ________________________________
 > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it
 > now.



Now, unfortunately I do not think this works for linux. Consider the 
small example given below:


#! /usr/bin/env python

import scipy as s
import numpy as n
import pylab as p

import visual as v


import Image
import ImageGrab

x_list=s.arange(10)
y_list=s.zeros(10)
y_list[:]=1.
z_list=y_list



box_size=100.
  
#v.scene = v.display(title="System Snapshot", width=box_size, 
height=box_size, x=0, y=0,
 #                range=box_size, center=(0.,0.,0.))

my_rad=1.

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


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

If I run it on my machine (Debian testing) then I got the following 
error message:

Traceback (most recent call last):
  File "<stdin>", line 11, in ?
  File "/usr/lib/python2.4/site-packages/PIL/ImageGrab.py", line 34, in ?
    import _grabscreen
ImportError: No module named _grabscreen

Is the module ImageGrab available for Debian (or for linux in general)? 
Or does anyone know of a workaround for this?
Many thanks

Lorenzo




























http://physics.syr.edu/~salgado/software/vpython/EMWave.py