visualpython-users

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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Scott Davis wrote:





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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...
>
>
>
>
>   

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...
>>