visualpython-users

[Visualpython-users] capture utility

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

Thanks to a user in France, this has been added to the FAQ:

CamStudio is a good freeware program for capturing to avi format on 
Windows (download at 
http://www.freedownloadscenter.com/Reviews/r1075.html); the help menu 
doesn't seem to work, but you can get help from the start menu entry for 
CamStudio. For capturing VPython animations you probably want to choose 
the menu option "Region" in which case when you start recording it waits 
for you to draw a capture rectangle.

Bruce Sherwood

Re: [Visualpython-users] Installation of Vpython

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

I'm not sure about other platforms, but at least on Windows Python 
itself offers a way to install without administrative privileges. I did 
this myself once. You might have to do this on a computer you control, 
because the VPython installer automatically will look for and find the 
existing python2.2. After installing the "rootless" Python, try 
installing VPython, and you'll be asked where to find Python (since 
there won't be anything in the registry to tell it where Python is). 
Tell the VPython installer to install into the Python directory. Now all 
you have to do is carry the whole Python directory to your office 
machine and put it in your own space.

Bruce Sherwood

sb...@ma... wrote:

> I would like to install Vpython on my office desktop on which,
>  unfortunately, I cannot be root. ( the system has got python2.2}
> 
> Is that possible?
> 
> Many thanks
> 
> Luca

[Visualpython-users] Installation of Vpython

[<sb...@ma...>]

I would like to install Vpython on my office desktop on which,
 unfortunately, I cannot be root. ( the system has got python2.2}

Is that possible?

Many thanks

Luca

Re: [Visualpython-users] Can I manipulate the light?

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

See this section of the on-line help for Visual:

Controlling Windows: display windows, lighting, and camera position

However, the current capabilities are rather limited (colored lights at 
infinity). Jonathan Brandmeyer is working on a major enhancement that 
will give sophisticated lighting capabilities, including spot lights, 
highlights, etc.

Bruce Sherwood

Frank Abel Cancio Bello wrote:

> Can I manipulate the light with vpython?
> __________________________________________
> 
> Aniversario 40 de la CUJAE
>  
> Visite:
>  
> XII Convencion de Ingenieria y Arquitectura
> http://www.cujae.edu.cu/eventos/convencion/

[Visualpython-users] Can I manipulate the light?

[Frank A. C. B. <fra...@te...>]

Can I manipulate the light with vpython?
__________________________________________

Aniversario 40 de la CUJAE
 
Visite:
 
XII Convencion de Ingenieria y Arquitectura
http://www.cujae.edu.cu/eventos/convencion/

Re: [Visualpython-users] gdisplay grid

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

It's quite easy. You just edit the graph.py module (which is written 
completely in Python) and add that option!

Seriously, it would be a good idea to offer that, and you might well 
find it doable, although the code is rather convoluted. Since I wrote it 
I can offer advice, but at the moment I'm not in a position to act on 
the suggestion myself.

Bruce Sherwood

Aaron Titus wrote:

> How can I show a grid on a graph using gdisplay?
> 
> Aaron

[Visualpython-users] gdisplay grid

[Aaron T. <ti...@ma...>]

How can I show a grid on a graph using gdisplay?

Aaron

Re: [Visualpython-users] The default output/debug window..

[Jonathan B. <jbr...@ea...>]

On Wed, 2004-09-22 at 16:44, jamesr wrote:
> Greeting VPython Users! A wonderfully rich-in-possiblities project. I
> do (of course) have a question:
> 
> The default output/debug window currently takes any print statements
> and sends them to an external window. Now I may have missed how to
> turn that off - but my major goal is to redirect that information to
> my textual interface which is a CURSES-managed window. On windows
> (where i am forced to work, for now), the curses window is yet again
> seperate from the debug and 3d windows. Can any of the developers
> and/or users point me out to how to redirect that text "somewhere
> else".
> 
> It could be cool!
> 
> thanks, and a first time poster,
> James Robey, Maryland.


# (where my_output is a some opened file or object that looks like a
file)
import sys
sys.stdout = my_output
sys.stderr = my_output

HTH,
-Jonathan

[Visualpython-users] The default output/debug window..

[jamesr <cir...@gm...>]

Greeting VPython Users! A wonderfully rich-in-possiblities project. I
do (of course) have a question:

The default output/debug window currently takes any print statements
and sends them to an external window. Now I may have missed how to
turn that off - but my major goal is to redirect that information to
my textual interface which is a CURSES-managed window. On windows
(where i am forced to work, for now), the curses window is yet again
seperate from the debug and 3d windows. Can any of the developers
and/or users point me out to how to redirect that text "somewhere
else".

It could be cool!

thanks, and a first time poster,
James Robey, Maryland.

Re: [Visualpython-users] How to plot only 'the last N points' using gcurve

[Gary <pa...@in...>]

Hans Fangohr wrote:

> Dear all, I am trying to use gcurve to continuously display the last N
> points of a scalar function. More concrete: a simulation goes through
> a number of iterations and for each iteration, I'd like to plot one
> scalar value. I want to display the last N points using gcurve.

I'm not exactly sure what you are trying to achieve, but I have 
something that seems similar.

I wanted a stripchart...  somthing that displays the latest data, while 
the older data falls off of the other end.   Pmw.Blt has a stripchart.  
So I married Pmw.Blt and Vpython.   An early demo is here: 

http://enigma.rider.edu/~gpajer/python.htm

(IT is warning us that this server may disappear soon ... so don't 
delay!)  since then I've spruced it up a bit, but this example displays 
various little features.  The code is a bit hard to read ... sorry about 
that.

It is also possible to make a stripchart using matplotlib 
(matplotlib.sf.net) .   It's much slower (see below). 

Blt seems no longer supported or developed, but it works.  A shame ... 
it has some nice features.  For some reason, it is hard to install.  I 
can attest that Pmw.Blt *does* work on Windows,  OS X,  and Linux.   
Windows instructions are on my weblink above.  On OS X, it installs and 
runs readily using fink.  Because of a bug in the configure script, 
Linux requires an environment variable ... can't recall it right now.  
I'll get it later if anyone wants it.


[commercial break:  nothing against matplotlib!!!  I find that the 
combination of ipython/scipy/matplotlib/Vpython  plus the non-pythonic 
Maxima makes a powerhouse of a scientific package.  More functionality 
than Matlab or Mathematica at none of the price.  And better support :)   ]

-gary

[Visualpython-users] How to plot only 'the last N points' using gcurve (program attached)

[Hans F. <H.F...@so...>]

Apologies: I noticed that the my mail client seems to have broken the
indentation in my previous email. This time I will attach the
program. Apologies for the 2nd email.

Regards,

Hans

On Tue, 21 Sep 2004, Hans Fangohr wrote:

> Dear all, I am trying to use gcurve to continuously display the last N
> points of a scalar function. More concrete: a simulation goes through
> a number of iterations and for each iteration, I'd like to plot one
> scalar value. I want to display the last N points using gcurve.
>
> Since I didn't see a way of deleting individual points from gcurve, I
> have written the little class (appended below) which does nearly what
> I want. What it doesn't do is to auto-scale the graph so that the last
> N points are displayed in optimal resolution. I am happy to compute
> the required min and max values for the y-axis myself but don't know
> how to pass it to vpython in the correct way.
>
> Can anybody help me? Or is this plotting of last N-points achievable
> much easier using another approach?
>
> Thank you,
>
> Hans
>
>
>
Please find program attached.

[Visualpython-users] How to plot only 'the last N points' using gcurve

[Hans F. <H.F...@so...>]

Dear all, I am trying to use gcurve to continuously display the last N
points of a scalar function. More concrete: a simulation goes through
a number of iterations and for each iteration, I'd like to plot one
scalar value. I want to display the last N points using gcurve.

Since I didn't see a way of deleting individual points from gcurve, I
have written the little class (appended below) which does nearly what
I want. What it doesn't do is to auto-scale the graph so that the last
N points are displayed in optimal resolution. I am happy to compute
the required min and max values for the y-axis myself but don't know
how to pass it to vpython in the correct way.

Can anybody help me? Or is this plotting of last N-points achievable
much easier using another approach?

Thank you,

Hans






import Numeric
import visual.graph

class PlotLastPoints:
     """plots the last N points of data that is provided subsequently.

     The first N-points are drawn using the usual
     vpython-gcurve(pos=[x,y]) method.

     After that, the first point is overwritten with the N+1 entry, the
     2nd point is replaced by the N+2 value etc.

     This is intended for a simulation where we have iterations on the
     x-axis, so the actual value there doesn't really matter.

     Bug: By not using gcurve's default mechanism for adding points,
     visual doesn't autoscale the graphs.
     """


     def __init__(self,N):
         self.N = N
         self.data=Numeric.zeros((N,),'d')
         self.last = 0
         self.disp=visual.graph.gdisplay(width=600,height=200)
         self.plot = visual.graph.gcurve()


         self.full = False  #have we more or exactly N points in self.data ?

     def update(self, E ):

         if self.full == False and (self.last == self.N):
             self.full = True

         if self.full:
             self.last = self.last % self.N
             self.data[self.last]=E
             self.plot.gcurve.x=Numeric.arange(self.N)[:]
             self.plot.gcurve.y=self.data[:]
         else:
             self.plot.plot(pos=[self.last,E])
             self.data[self.last]=E

         self.last +=1


if __name__=="__main__":


     import math,time

     plot = PlotLastPoints(50)

     for i in range(2000):
         plot.update( math.sin(i/50.0))
         time.sleep(0.02)

[Visualpython-users] New Job

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

I recently accepted a position at a public school. I
have the combined duties of computer lab supervisor
and technical support person for an entire building
(about 75 to 100 computers plus related equipment).

I think that my new situation presents some
(V)Python-related opportunities, but they need to be
approached quite carefully. For one thing, my employer
is *VERY* conservative, in *all* meanings of the term.
Each new idea, program, gadget, &c that might be
introduced has to go through a *serious* bureaucratic
gauntlet. The administration of the school itself has
extremely limited power; key decisions are made at the
district level. Another important point: this is a K-2
school, and there are issues about how one can use
Python as an educational tool for
six-to-eight-year-olds.

My short-term wish list:

1. Could someone donate a laptop that they are no
longer using? This school has some, but they are all
under tight restrictions (see above) and I will need
to have a machine that I can experiment on. The main
processor doesn't have to be cutting edge, of course,
but a lot of RAM would be helpful, and the hard drive
should be large enough for a dual partition between
Windows and Linux that I might be tinkering with at
some future time. A few spare batteries would also be
good. Because of various ugly bureaucratic rules, the
donation would have to be to me personally, *not* to
the school; this might affect any tax breaks that you
were hoping to get. However, I can still give plenty
of favorable publicity to whichever person(s) and/or
firm(s) make the donation possible. :-)

2. I'd like to get some gear to connect a computer to
a TV/VCR so that the image going to the computer's
monitor will also display directly on the TV and can
be recorded on VHS. We already have the TV/VCR in our
computer lab, and a computer has been set aside for
this project too; we just need the hookup stuff. In
this case, the gadget *would* belong to the school,
and it just *might* be purchased out of the school's
budget. Of course, a donated item certainly would be
accepted, as long as the thing works properly.

3. I'm looking for an education-oriented version of
Knoppix that can run reliably on a very old Pentium
machine with limited RAM and disk space. The CD should
be in English; I stress this because there seem to be
several education Knoppixes in various European
languages, but I'm having a hard time finding an
English one. And remember the age group that I'm
dealing with: six to eight years.

This is a start. I'm open to suggestions, but keep in
mind that change is real slow at this place.

Joel



		
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[Visualpython-users] Python Version 2.3.4 Idle Problem

[David P. <dp...@dr...>]

Guys
	This may not be the proper site for this but maybe someone can direct the message in the right direction. Some may have noticed that Idle will no longer start. I believe that this is may be the result of the latest update from Microsoft. I have Python V2.3.4 on 2 work computers and on my home computer. The latest update was applied to my  home pc on Tuesday night. On Wednesday Idle would not work on all 3 machines. This affects (at least) WinXP and Win2K so if you have not applied the latest update you may consider holding off this the Python crew can come up with a fix.
	Regards 
	Dave P.

[Visualpython-users] RE: [Edu-sig] Images in VPython: Faces

[Arthur <ajs...@op...>]

> -----Original Message-----
> From: edu...@py... [mailto:edu...@py...] On
> Behalf Of Joel Kahn
> Sent: Thursday, September 09, 2004 4:42 PM
> To: vis...@li...; ed...@py...
> Subject: [Edu-sig] Images in VPython: Faces
> 
> The attached script contains another approach to the
> process of displaying images in VPython. Instead of
> there being an object for each "pixel," two triangles
> on a faces object are placed together to produce a
> square, as noted in the appropriate comment lines. As
> with my "objects" example, I kept this prototype as
> simple as possible; there are many things that could
> be done with varying normals, z-axis-positions, &c
> that I haven't touched yet.
> 
> The new "faces" algorithm delivers the image to the
> screen significantly more quickly than the "objects"
> system, and it seems to be able to handle much higher
> resolution pictures; still, I suggest beginning your
> experiments with small bitmaps to play it safe.
> 
> As always, feedback is encouraged.

I hadn't had PIL installed, and it wasn't downloading went I first went to
get it, so I hadn't been able to look at this before.

I can now, and so did now.

I hadn't had PIL because I've never have done much outside of vector
graphics.  

I am used to working at the graphics object level, not the pixel level. 

I think your demo ties the two concepts together in a fun way.

Thanks,

Art

[Visualpython-users] Images in VPython: Faces

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

The attached script contains another approach to the
process of displaying images in VPython. Instead of
there being an object for each "pixel," two triangles
on a faces object are placed together to produce a
square, as noted in the appropriate comment lines. As
with my "objects" example, I kept this prototype as
simple as possible; there are many things that could
be done with varying normals, z-axis-positions, &c
that I haven't touched yet.

The new "faces" algorithm delivers the image to the
screen significantly more quickly than the "objects"
system, and it seems to be able to handle much higher
resolution pictures; still, I suggest beginning your
experiments with small bitmaps to play it safe.

As always, feedback is encouraged.

Joel


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[Visualpython-users] images in Python

[Bruce P. <bap...@te...>]

At 10:47 AM 9/9/2004, you wrote:
>--__--__--
>
>Message: 11
>Date: Thu, 09 Sep 2004 13:46:11 -0400
>From: Bruce Sherwood <Bru...@nc...>
>To: vis...@li...
>Subject: Re: [Visualpython-users] images in VPython
>
>The last time this was discussed it wasn't clear what were "the standard
>3D formats". Has that settled out?
>
>A slightly different take on the import issue would be for people to
>write importers (in Python) that take a 3D model in their favorite
>format and generate Visual code (using faces, for example).
>
>Bruce Sherwood

I used the phrase "the standard 3D formats" because a quick Google search 
turned up a half dozen or more programs that purport to translate among 
various 3D object formats. I assume that if any common format is selected 
for support into VPython, then most any other common format could be 
translated to this using one of these translators.

Knowing nothing about the architecture being developed, I don't know 
whether it would be more efficient to have object importation as part of 
the graphics engine or as a Python model. My assumption was that object 
importation would be part of the graphics engine.


Bruce Peterson, Ph.D.
Terastat, Inc
Information Access Systems
Voice (425) 466 7344
Fax (206) 350 3685 

Re: [Visualpython-users] last, desperate call for help

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

I'm not competent to comment directly, but could you perhaps handle this 
with more distance between your main application and the VPython viewer? 
For example, I have a Python program that helps with the logistics of 
grading student programs written in VPython (for an introductory physics 
course). The key statement is "exec(text)", where text was read from a 
file (exec is in the os module). At least as an experiment, you could 
write out information for VPython, do an exec of the VPython program, 
read up that information, and make the 3D display. Crude, inefficient, 
but it's hard to see how it could fail to work.

Bruce Sherwood

Fionn Behrens wrote:

>Hi all,
>
>
>I have asked earlier, I do it again. We have a project here that needs 3d
>output. the UI itself ist done in python-gtk.
>We fail to manage starting vpython out of our gtk application. First the
>two mainloops collided, so people told us to use python-gtk2 and threads.
>
>So we switched the Ui to python-gtk2 and use threads. Similar to the
>tk-demo thats coming with python-visual, we start python-visual in its own
>thread.
>The good news: no more mainloop clashing. The bad news: It segfaults
>immediately, leaving loads of messages on the screen that look like this:
>
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
>(<unknown>:13237): Gtk-WARNING **: gtk_type_create(): unknown parent type `21'.
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
>(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
>(<unknown>:13237): Gtk-WARNING **: gtk_type_create(): unknown parent type `21'.
>(<unknown>:13237): Gtk-CRITICAL **: file gtktypeutils.c: line 337 (gtk_type_class): assertion `node != NULL' failed.
>(<unknown>:13237): Gtk-WARNING **: gtk_arg_type_new(): argument class in "GtkContainer::border_width" is not in the `(null)' ancestry
>
>...
>
>Please, please, if anyone EVER managed to start vpython from a gtk gui or
>has any tip on what might have gone wrong, send it!
>
>Desperate,
>		Fionn
>
>
>
>
>
>-------------------------------------------------------
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>Project Admins to receive an Apple iPod Mini FREE for your judgement on
>who ports your project to Linux PPC the best. Sponsored by IBM. 
>Deadline: Sept. 13. Go here: http://sf.net/ppc_contest.php
>_______________________________________________
>Visualpython-users mailing list
>Vis...@li...
>https://lists.sourceforge.net/lists/listinfo/visualpython-users
>  
>

Re: [Visualpython-users] images in VPython

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

The last time this was discussed it wasn't clear what were "the standard 
3D formats". Has that settled out?

A slightly different take on the import issue would be for people to 
write importers (in Python) that take a 3D model in their favorite 
format and generate Visual code (using faces, for example).

Bruce Sherwood

Bruce Peterson wrote:

>
>> >>>snip
>>
>> Cluster?  No, I think that would be a bad idea for VPython.  Any recent
>> video card will be able to handle pretty much anything you can throw at
>> it from VPython.  A scene with several translucent and textured objects,
>> some using a source image of 1024x2048 pixels, can be rendered in only a
>> few ms on common PC hardware.  You really can't notice that it takes any
>> time at all, and the UI remains buttery-smooth.
>>
>> Speed is not the problem.  Picking the right parts of a complex
>> environment (or completely reformulating the appearance of what you are
>> doing) to expose to client programs in Python is the hard part, and that
>> is what I would appreciate some feedback on.
>>
>> -Jonathan
>
>
> One of the favorable attributes of VPython is its ability to quickly 
> focus on the dynamics of an animation. Rather than trying to duplicate 
> the functionality of POV-Ray or other 3D rendering packages, why not 
> let VPython import objects (stored in one of the standard 3D formats) 
> created in a 3D rendering package. This would minimize the number of 
> attributes that need to be exposed in VPython and let the bulk of the 
> object creation be done in an appropriate package.
>
>
>
> Bruce Peterson
> 425 466 7344
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by: YOU BE THE JUDGE. Be one of 170
> Project Admins to receive an Apple iPod Mini FREE for your judgement on
> who ports your project to Linux PPC the best. Sponsored by IBM. 
> Deadline: Sept. 13. Go here: http://sf.net/ppc_contest.php
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

Re: [Visualpython-users] last, desperate call for help

[Jonathan B. <jbr...@ea...>]

On Thu, 2004-09-09 at 13:04, Fionn Behrens wrote:
> Hi all,
> 
> 
> I have asked earlier, I do it again. We have a project here that needs 3d
> output. the UI itself ist done in python-gtk.
> We fail to manage starting vpython out of our gtk application. First the
> two mainloops collided, so people told us to use python-gtk2 and threads.
> 
> So we switched the Ui to python-gtk2 and use threads. Similar to the
> tk-demo thats coming with python-visual, we start python-visual in its own
> thread.
> The good news: no more mainloop clashing. The bad news: It segfaults
> immediately, leaving loads of messages on the screen that look like this:

Unfortunately, running Visual in a separate thread isn't enough - to be
totally safe right now, VPython has to be run in a separate process. 
The Gtk process would have to communicate with the Visual process using
a pipe, socket, or some other IPC mechanism.  However, there is hope.

Some significant work is being done to separate the OpenGL management
from the windowing system management, such that you will be able to
render a VPython scene into a toolkit-specific OpenGL window.  The
initial release of that functionality will include a PyGtkGLext-based
widget (gtkglext.sourceforge.net), since I am familiar with that
package.  It will also include the capability to do the same for other
toolkits in pure Python.

-Jonathan

[Visualpython-users] last, desperate call for help

[Fionn B. <fi...@sp...>]

Hi all,


I have asked earlier, I do it again. We have a project here that needs 3d
output. the UI itself ist done in python-gtk.
We fail to manage starting vpython out of our gtk application. First the
two mainloops collided, so people told us to use python-gtk2 and threads.

So we switched the Ui to python-gtk2 and use threads. Similar to the
tk-demo thats coming with python-visual, we start python-visual in its own
thread.
The good news: no more mainloop clashing. The bad news: It segfaults
immediately, leaving loads of messages on the screen that look like this:

(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
(<unknown>:13237): Gtk-WARNING **: gtk_type_create(): unknown parent type `21'.
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 291 (g_hash_table_insert): assertion `hash_table != NULL' failed
(<unknown>:13237): GLib-CRITICAL **: file ghash.c: line 225 (g_hash_table_lookup): assertion `hash_table != NULL' failed
(<unknown>:13237): Gtk-WARNING **: gtk_type_create(): unknown parent type `21'.
(<unknown>:13237): Gtk-CRITICAL **: file gtktypeutils.c: line 337 (gtk_type_class): assertion `node != NULL' failed.
(<unknown>:13237): Gtk-WARNING **: gtk_arg_type_new(): argument class in "GtkContainer::border_width" is not in the `(null)' ancestry

...

Please, please, if anyone EVER managed to start vpython from a gtk gui or
has any tip on what might have gone wrong, send it!

Desperate,
		Fionn

[Visualpython-users] images in VPython

[Bruce P. <bap...@te...>]

> >>>snip
>
>Cluster?  No, I think that would be a bad idea for VPython.  Any recent
>video card will be able to handle pretty much anything you can throw at
>it from VPython.  A scene with several translucent and textured objects,
>some using a source image of 1024x2048 pixels, can be rendered in only a
>few ms on common PC hardware.  You really can't notice that it takes any
>time at all, and the UI remains buttery-smooth.
>
>Speed is not the problem.  Picking the right parts of a complex
>environment (or completely reformulating the appearance of what you are
>doing) to expose to client programs in Python is the hard part, and that
>is what I would appreciate some feedback on.
>
>-Jonathan

One of the favorable attributes of VPython is its ability to quickly focus 
on the dynamics of an animation. Rather than trying to duplicate the 
functionality of POV-Ray or other 3D rendering packages, why not let 
VPython import objects (stored in one of the standard 3D formats) created 
in a 3D rendering package. This would minimize the number of attributes 
that need to be exposed in VPython and let the bulk of the object creation 
be done in an appropriate package.



Bruce Peterson
425 466 7344 

Re: [Visualpython-users] autoscale

[Jonathan B. <jbr...@ea...>]

On Thu, 2004-09-09 at 11:37, Aaron Titus wrote:
> I've noticed that in the orbit demo program, the autoscale causes the 
> scene to scale even when it's not needed. For example, the paths of the 
> orbits are closed, so once an orbit it completed, it should need to 
> zoom in or out. However, it does anyway.

It does that because the "bounding box" that Visual uses to determine
the autoscaling is slightly larger whenever the outer sphere is on the
far left, right, near, or far edge of the scene.  We have been thinking
about an appropriate means of controlling this kind of situation, but
haven't settled down on a solution, yet.

> Besides setting the size of the window and turning off autoscaling, is 
> there a way to make the window not zoom in and out as the stars orbit?

In the meantime, you can try setting the undocumented parameter
display.minscale to something like 0.9.  Feel free to experiment with
it, but I think it is a relic from some internal testing before my
time.  It's behavior will change in the future (maybe even replaced)
with something more suitable for public consumption.  You probably
shouldn't set it outside the range (0,1].

-Jonathan

[Visualpython-users] autoscale

[Aaron T. <ti...@ma...>]

I've noticed that in the orbit demo program, the autoscale causes the 
scene to scale even when it's not needed. For example, the paths of the 
orbits are closed, so once an orbit it completed, it should need to 
zoom in or out. However, it does anyway.

Besides setting the size of the window and turning off autoscaling, is 
there a way to make the window not zoom in and out as the stars orbit?

Thanks,

AT

Re: [Visualpython-users] Images in VPython

[Jonathan B. <jbr...@ea...>]

On Thu, 2004-09-09 at 10:20, Jonathan Brandmeyer wrote:
>   You can only really set
> transparency for an individual zero-thickness planar triangle in
> OpenGL.  

That is not strictly true.  You can also specify it for a point, whose
size is measured in pixels.  Flames and fog clouds are done this way, in
games, and the tech to do it is commonly called a 'particle engine', if
you want to google for more info.

Visual doesn't have a 'points' object yet, but a team in Australia is
working on one.  I don't know if they intend to imbue it with particle
engine functionality, but I think it is meant to be more like the
'curve' object.

-Jonathan