visualpython-users

Re: [Visualpython-users] Re: Py2exe, movable python

[keridee <ke...@ja...>]

Py2exe is supposed to work with Vpython (I like to call it Vpython because
Visual Python is a Visual Studio extension written by Microsoft) already...
I believe testimony to this can be found at http://www.vpython.org/FAQ.html

Maybe you already have seen this, maybe not.
Jacob Schmidt


----- Original Message -----
From: John Brawley <jb...@te...>
To: <vis...@li...>
Sent: Thursday, January 05, 2006 11:14 AM
Subject: [Visualpython-users] Re: Py2exe, movable python


> Query:
> I'd love to be able to run a VPython script as a program on a Windows
> machine with no Python/VPython installed.
> Py2exe does this, "movable Python" may also, and there are a couple of
other
> ways, including the upcoming IronPython that will "natively" use Windows
> Vista's GUI libraries.
>
> The question is, will any of these methods work with Visual Python, or
not?
> (In other words, is there anything in the works to make VPython compatible
> with Python implementations that can convert VPython programs to
executables
> that will run on Windows as .exes or as if they were .exes?
>
> (I hate the thought of having to either learn C++, or having to learn
> OpenGL....)
>
> thanks!
>
> Peace
> JB
> jb...@te...
> Web: http://tetrahedraverse.com
>
>
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through log
files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>

[Visualpython-users] Re: Py2exe, movable python

[John B. <jb...@te...>]

Query:
I'd love to be able to run a VPython script as a program on a Windows
machine with no Python/VPython installed.
Py2exe does this, "movable Python" may also, and there are a couple of other
ways, including the upcoming IronPython that will "natively" use Windows
Vista's GUI libraries.

The question is, will any of these methods work with Visual Python, or not?
(In other words, is there anything in the works to make VPython compatible
with Python implementations that can convert VPython programs to executables
that will run on Windows as .exes or as if they were .exes?

(I hate the thought of having to either learn C++, or having to learn
OpenGL....)

thanks!

Peace
JB
jb...@te...
Web: http://tetrahedraverse.com

[Visualpython-users] Vpython rendering in an other window

[linux\.power <lin...@la...>]

Hello everybody,

To present myself, I'm a Fabrice Tiercelin's colleague and we
are working on a circular GUI at french university. This
window aims to present a 3D rendering.

In one hand we have choosed to use Python and PyGTK library in
order to show a circular window. We succedded it !

In an other hand we use Vpython to perform 3D rendering. It
works well :)

Our trouble is now to retrieve the Vpython component in order
to place it into the PyGTK window.

We don't know which library is used in Vpython for window so
we don't managed to retrieve it :(.

I precise that we work under Linux and it does not matter if
it does not work under windows.

Do you know how to insert Vpython rendering in PyGTK window ?
Is it possible ?

It's clear that we would like to use our PyGTK window ...
But how can we do it with an other Toolkit Library ?

Thanks a lot !

We believe in your advices !=0A=0AAcc=E9dez au courrier =E9lectronique de=
 La Poste : www.laposte.net ;=0AJusqu'au 25 d=E9cembre, participez  au gr=
and jeu du Calendrier de l'Avent et=0A=A0gagnez tous les jours de nombreu=
x lots, + de 300 cadeaux en jeu !=0A=0A

Re: [Visualpython-users] Right, so I made this dinky spaceship...

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

I think there's a typo in the definition of +y. It should be

+x = object.axis.norm()
+z = object.axis.cross( object.up).norm()
+y = -x.cross( +z) (implicitly orthonormal to x and z)

Bruce Sherwood

Jonathan Brandmeyer wrote:

>On Thu, 2005-12-22 at 22:38 -0500, Jeremy Sachs wrote:
>  
>
>>Hi again. I'm very confused by the methods you can use to rotate an
>>object, specifically a frame.
>>    
>>
>
>Hopefully this explanation will help.
>
>VPython uses 2 vectors to specify the orientation of its objects: axis
>and up.  The coordinate system of the local reference frame (for any
>object, including frame objects) is defined such that
>
>+x = object.axis.norm()
>+z = object.axis.cross( object.up).norm()
>+y = +x.cross( +z) (implicitly orthonormal to x and z)
>
>Another way to say this, is that +y is always coplanar to axis and up,
>orthogonal to axis, such that +y.diff_angle( up ) <= 90 (in degrees)
>
>  
>
>>I made this model spaceship that I want to animate, such that the ship
>>is always pointed in the direction that it's moving. The objects that
>>make up the ship are grouped together in a frame, so that
>>repositioning and rotating the model is a simpler process. The idea is
>>to derive all the necessary information from one vector, called
>>"dndt", that represents the velocity of the ship. That way, if I want
>>to edit the path of the ship, the code that rotates the ship won't
>>break. I've fiddled with the "axis" property of the frame object, and
>>have just gotten really confused. 
>>
>>
>>My program is a big mess, so I made a smaller example file, which is
>>at http://homepage.mac.com/rezmason/spaceship.py . It's very basic,
>>and you can use it however you wish.
>>
>>
>>Thanks,
>>-JS
>>    
>>
>
>
>
>-------------------------------------------------------
>This SF.net email is sponsored by: Splunk Inc. Do you grep through log files
>for problems?  Stop!  Download the new AJAX search engine that makes
>searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
>http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
>_______________________________________________
>Visualpython-users mailing list
>Vis...@li...
>https://lists.sourceforge.net/lists/listinfo/visualpython-users
>  
>

Re: [Visualpython-users] Right, so I made this dinky spaceship...

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

On Thu, 2005-12-22 at 22:38 -0500, Jeremy Sachs wrote:
> Hi again. I'm very confused by the methods you can use to rotate an
> object, specifically a frame.

Hopefully this explanation will help.

VPython uses 2 vectors to specify the orientation of its objects: axis
and up.  The coordinate system of the local reference frame (for any
object, including frame objects) is defined such that

+x = object.axis.norm()
+z = object.axis.cross( object.up).norm()
+y = +x.cross( +z) (implicitly orthonormal to x and z)

Another way to say this, is that +y is always coplanar to axis and up,
orthogonal to axis, such that +y.diff_angle( up ) <= 90 (in degrees)

> I made this model spaceship that I want to animate, such that the ship
> is always pointed in the direction that it's moving. The objects that
> make up the ship are grouped together in a frame, so that
> repositioning and rotating the model is a simpler process. The idea is
> to derive all the necessary information from one vector, called
> "dndt", that represents the velocity of the ship. That way, if I want
> to edit the path of the ship, the code that rotates the ship won't
> break. I've fiddled with the "axis" property of the frame object, and
> have just gotten really confused. 
> 
> 
> My program is a big mess, so I made a smaller example file, which is
> at http://homepage.mac.com/rezmason/spaceship.py . It's very basic,
> and you can use it however you wish.
> 
> 
> Thanks,
> -JS

[Visualpython-users] Right, so I made this dinky spaceship...

[Jeremy S. <rez...@ma...>]

Hi again. I'm very confused by the methods you can use to rotate an  
object, specifically a frame.

I made this model spaceship that I want to animate, such that the  
ship is always pointed in the direction that it's moving. The objects  
that make up the ship are grouped together in a frame, so that  
repositioning and rotating the model is a simpler process. The idea  
is to derive all the necessary information from one vector, called  
"dndt", that represents the velocity of the ship. That way, if I want  
to edit the path of the ship, the code that rotates the ship won't  
break. I've fiddled with the "axis" property of the frame object, and  
have just gotten really confused.

My program is a big mess, so I made a smaller example file, which is  
at http://homepage.mac.com/rezmason/spaceship.py . It's very basic,  
and you can use it however you wish.

Thanks,
	-JS

[Visualpython-users] vPython window in a gtk interface

[Fabrice T. <fab...@in...>]

Hello,

We are developping a program with a gtk interface. We have already
integrated images on it but now we wish to include a 3D preview on it from
vPython. Is there anybody who knows how to put a 3D preview window of
vPython into a graphic interface of gtk ?

thanks,
Fabrice TIERCELIN

[Visualpython-users] Kids & VPython

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

John Brawley, addressing me, wrote:

>You must be either a 
>saint or a masochist.

Actually, "masochist" is probably a more 
accurate term than "saint" is. :-) In any
case, working on computers with this age 
group does have its compensations. One can
learn quite a bit from these kids; one just
has to avoid a common occupational disease 
of techies: trying to pretend that one is 
smarter than everyone else. In my job, I 
know that I will frequently see little kids
demonstrate clearly that they are much more
intelligent than I am. This comes with the
territory. Grown-ups with egos that can't 
handle this don't belong on this turf.

Anyway, thanks to John Brawley for the tip
on the TVLiveST.py program. I'll see when I
get a chance to try it out--soon, I hope.
While I'm on this, I'd like to toss out an
idea that I've been mulling over for a 
while. Those of you who are using VPython
as a tool to teach programming to college
and high school students could suggest or 
assign the following project to your classes:
Write a program that could be used by young
children to learn solid geometry and related
subjects. If programs like these were emailed
to me, posted on the web, or whatever, I 
could use my lab as an experimental test 
site to see how well they actually worked.
I hopefully could also get more material
than I will ever have time to assemble
myself, conditions being what they are.

Any programming students who wanted to get
involved should keep a few things in mind:

First, the obvious: the target audience has
a lower age limit of five and an upper age
limit of eight. Activities should be made
suitable for that range.

Second: the operating system used here is 
Windows XP Professional.

Third: the hardware that each student uses
is a desktop system with a 2.8Ghz Pentium
4 HT and 512MB of RAM. The machine on my 
desk (connected to a SmartBoard) is a 
3.4Ghz P4 HT with 1GB of RAM. Disk space 
is a non-issue, since all relevant storage
is done on network drives with hundreds of 
gigs of available space. In other words,
the programmers can go crazy and not worry
about pushing things too far. Include all
of the splashy special effects you want;
kids in this age group love that stuff.

Fourth: I'm not sure exactly how soon I'd
be able to put the programs in front of the
children. This school, and the district that
it belongs to, are not regular (V)Python
users; in fact, one of my goals in suggesting
this project is to see if I can get one or
more things that might impress my principal
and other administrators enough so that they
would look at adopting Python broadly.
(Right now, I'm just tinkering with VPython
very informally with a few classes at some
limited times.) Although the bigwigs here
love to make noises about "innovation,"
getting any actual change through the slow
bureaucracy can be a major ordeal.

I hope this is enough to get some people
thinking. I await your questions, feedback,
suggestions, and whatever else.

Joel


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 

[Visualpython-users] Version 3.2.5

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

2005-12-20 Version 3.2.5: Restores missing component of (optional) 
numarray module; corrects spelling in documentation of 
display.get_selected(); uses this feature in graph.py rather than the 
old kludge of creating an invisible sphere to save and restore the 
currently selected display when creating a gdisplay object.

Bruce Sherwood

Re: [Visualpython-users] wave.py conflict

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

On Tue, 2005-12-20 at 10:48 +0100, Laurent Pierron wrote:
> Hello Bruce,
> 
> When you use VPython to analyse audio signals, there is a conflict 
> between the modules wave.py from Python's standard library and wave.py 
> from VPython's demos programs.

I don't understand; wave.py should never be on the module search path.
How is it getting imported instead of the wave module?

> I know how to manage with this conflict, but I think it would be better 
> if you could rename the module wave.py as waves.py in the distribution 
> of VPython.

-Jonathan

[Visualpython-users] wave.py conflict

[Laurent P. <Lau...@lo...>]

Hello Bruce,

When you use VPython to analyse audio signals, there is a conflict 
between the modules wave.py from Python's standard library and wave.py 
from VPython's demos programs.

I know how to manage with this conflict, but I think it would be better 
if you could rename the module wave.py as waves.py in the distribution 
of VPython.

VPython is great.

Thanks a lot.

----
Laurent PIERRON

Re: [Visualpython-users] Visual 3.2.4

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

On Mon, 2005-12-19 at 18:48 -0500, Jeremy Sachs wrote:
> I'm working on a program that draws a continuous curve, and when the  
> number of points on that curve exceeds 1024, a new curve is drawn at  
> the end of the old curve.
> 
> How many 1024-point curves can visual python manage before crashing?

Here goes a long answer to a simple question...

It should go until you run out of physical RAM.  For N points, the
maximum memory usage is 2*3*sizeof(double)*2*N, or 48 bytes per point,
but it can be as few as 24 bytes per point.

Curve objects preallocate storage for up to 2x the total number of
points in order to make curve.append() work fast.  When using .append(),
the total allocated storage is approximated by min( 256, 2^X) for
incrementally increasing values of X (it is actually slightly more than
this).  If you precalculate the curve's pos or color array rather than
simply append() to it, the storage will be enough for exactly 2x the
size of the initial array (doubling as needed for subsequent appends).
You don't normally see this extra allocation since curve.pos is actually
a slice into the real pos array.

For your usage pattern, the extra space will be small, and total storage
will be a pinch larger than 24 bytes per point.  There's also some
per-object overhead which should be pretty small compared to the storage
required for the points themselves.  Therefore, per-object memory usage
should be about 24-25K per 1024-point curve segment.

As far as rendering goes, curves with zero radius (the default) are
rendered much much faster than thick curves.

HTH,
-Jonathan

Re: [Visualpython-users] Visual 3.2.4

[Jeremy S. <rez...@ma...>]

I'm working on a program that draws a continuous curve, and when the  
number of points on that curve exceeds 1024, a new curve is drawn at  
the end of the old curve.

How many 1024-point curves can visual python manage before crashing?

-Jeremy S.



On Dec 19, 2005, at 2:01 PM, Bruce Sherwood wrote:

> curve now always plots final point (so there isn't a gap at the end),
>
> The gap at the end of a curve only showed up with curves longer  
> than 1024 points. For such curves, Visual uses only every Nth point  
> to display the curve, up to a total of 1024 displayed points. The  
> bug was that the last of these selected points wasn't always the  
> last point in the full curve, creating a gap at the end of the  
> displayed object.
>
> Bruce Sherwood

Re: [Visualpython-users] continued difficulties in OS X

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

open /Applications/Utilities/X11.app

will start X11.

As far as /sw/bin not being in the path, just create a symbolic link  
to vpython in /usr/bin. To create a symbolic link, use

ln -s /sw/bin/vpython vpython

Now, typing "vpython" will open vpython.

Generally, I edit my python files in a text editor BBedit (an often  
used programmer's editor for the Mac) and run the python files from  
the command line. However, if you type "python filename.py" then you  
will run the Mac python installation which doesn't have visual. You  
have to run the Fink distribution of python. I created a symbolic  
link called "py" that points to /sw/bin/vpython2.3.

That allows me to run my python programs from the command line by  
typing "py filename.py".

On Dec 19, 2005, at 2:39 PM, Jonathan Brandmeyer wrote:

> On Mon, 2005-12-19 at 13:21 -0600, Lenore Horner wrote:
>> Thank you Aaron, Martin, and Gary for your help.  Martin's suggestion
>> to look at "fink describe visual-py23"  (which turns into "show
>> package info" in Fink Commander) got me the piece I needed.  I have
>> to manually start X11 and then use /sw/bin/vpython.
>
> If anyone knows how to start Apple's X server from the command-line,
> that action can be integrated to /sw/bin/vpython.
>
> -Jonathan
>
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through  
> log files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD  
> SPLUNK!
> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>

Re: [Visualpython-users] continued difficulties in OS X

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

On Mon, 2005-12-19 at 13:21 -0600, Lenore Horner wrote:
> Thank you Aaron, Martin, and Gary for your help.  Martin's suggestion  
> to look at "fink describe visual-py23"  (which turns into "show  
> package info" in Fink Commander) got me the piece I needed.  I have  
> to manually start X11 and then use /sw/bin/vpython.

If anyone knows how to start Apple's X server from the command-line,
that action can be integrated to /sw/bin/vpython.

-Jonathan

Re: [Visualpython-users] continued difficulties in OS X

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

Actually, the mouse button bindings can be chosen by you. It is a 
feature of the X window system that the end user gets to specify how to 
interpret mouse+keyset; I think it's a menu option to get to this. 
Apparently the bindings mention in the tutorial refer to an older system.

Bruce Sherwood

Lenore Horner wrote:

> Thank you Aaron, Martin, and Gary for your help.  Martin's suggestion  
> to look at "fink describe visual-py23"  (which turns into "show  
> package info" in Fink Commander) got me the piece I needed.  I have  
> to manually start X11 and then use /sw/bin/vpython.
>
> I'm using OS X 10.4.3, X11 1.1 - XFree86 4.4.0 with an Apple  
> copyright as well, and visual-py23 2.1.9-6.
>
> I do have to use /sw/bin/vpython rather than vpython as X11  
> apparently doesn't have /sw/bin in the path and I haven't (yet) fixed  
> that.
>
> I'm working my way not through VPython_Intro.pdf.  I note that on the  
> Mac, it is cmd-mouse to move the camera and option-mouse to zoom as  
> opposed to shift and cmd respectively as noted in the file.
>
> Thanks again.
>
> Lenore
>
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through log 
> files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

[Visualpython-users] continued difficulties in OS X

[Lenore H. <lh...@si...>]

Thank you Aaron, Martin, and Gary for your help.  Martin's suggestion  
to look at "fink describe visual-py23"  (which turns into "show  
package info" in Fink Commander) got me the piece I needed.  I have  
to manually start X11 and then use /sw/bin/vpython.

I'm using OS X 10.4.3, X11 1.1 - XFree86 4.4.0 with an Apple  
copyright as well, and visual-py23 2.1.9-6.

I do have to use /sw/bin/vpython rather than vpython as X11  
apparently doesn't have /sw/bin in the path and I haven't (yet) fixed  
that.

I'm working my way not through VPython_Intro.pdf.  I note that on the  
Mac, it is cmd-mouse to move the camera and option-mouse to zoom as  
opposed to shift and cmd respectively as noted in the file.

Thanks again.

Lenore

[Visualpython-users] Visual 3.2.4

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

Version 3.2.4 now available at vpython.org (and SourceForge) fixes the 
following errors:
1) curve now always plots final point (so there isn't a gap at the end),
2) diff_angle(a,b) is 0 if either a.mag or b.mag is 0 instead of pi/2 
(one could argue that it should be an error, or NaN, "not a number", but 
making the result zero is consistent with norm(vector(0,0,0)) is also zero),
3) frame documentation changed to explain that frame.objects list only 
visible objects,
4) makes display.exit = 0 again work (only a single graphics window 
closes when you click its close box).

The gap at the end of a curve only showed up with curves longer than 
1024 points. For such curves, Visual uses only every Nth point to 
display the curve, up to a total of 1024 displayed points. The bug was 
that the last of these selected points wasn't always the last point in 
the full curve, creating a gap at the end of the displayed object.

Bruce Sherwood

Re: [Visualpython-users] How to compile the 'vpython' while using the 'CVS' snapshot.

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

On Sun, 2005-12-18 at 12:07 +0800, samuel wrote:
> Hi,
> 
> i'm a newbie@Taiwan in using vpython for developing my favorite
> physics tutorial, and now i'm using the Ubuntu-5.10 distro.

I'm running Debian Sid right now, so I hope these directions work for
you...

> after snapshotting the latest nightly 'cvs' from sourceforge, i would
> like to compile the vpython.
> 
> But i couldn't find the 'configure' the in the 'cvs' tree, how did i
> compile and install the vpython?

Configure and kin are not normally kept in CVS.

> i've already install the 'scipy' and 'boost' already, did i need to
> install the 'automake' or 'autoconf' to proceed the compiling steps
> further?

# apt-get build-dep python-visual
# apt-get install automake1.9 autoconf libtool

Then run autogen.sh (you may need to make it executable with chmod).

HTH,
-Jonathan

[Visualpython-users] How to compile the 'vpython' while using the 'CVS' snapshot.

[samuel <sam...@gm...>]

Hi,

i'm a newbie@Taiwan in using vpython for developing my favorite
physics tutorial, and now i'm using the Ubuntu-5.10 distro.

after snapshotting the latest nightly 'cvs' from sourceforge, i would
like to compile the vpython.

But i couldn't find the 'configure' the in the 'cvs' tree, how did i
compile and install the vpython?

i've already install the 'scipy' and 'boost' already, did i need to
install the 'automake' or 'autoconf' to proceed the compiling steps
further?

--
Best Regards,
----------------------------------------
samuel

[Visualpython-users] display.exit fix

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

There is an easy fix for the display.exit bug.  Add the following line
to the definition of class display in site-packages/visual/ui.py:

(one tab)exit = property(None, cvisual.display.exit_on_close, None)

This and a handful of other issues will be corrected in an upcoming
release.

HTH,
-Jonathan Brandmeyer

[Visualpython-users] Re: Demons exorcised, and an offering

[John B. <jb...@te...>]

> From: Joel Kahn <jj...@ya...>
> To: vis...@li...
> Subject: [Visualpython-users] Demonic Computers
> John Brawley wrote:
> >I am close to thinking computers and
> >their programs are actually demons
> >viciously sitting on our desktops
> >waiting for the moment we are most vulnerable....
>
> You are only *close* to thinking this?!
> I run the computer lab at a public primary school. In
> this case, "primary" means kindergarten through second
> grade. If you are only *close* to thinking that
> computers are demons, you have clearly never seen
> twenty-five Windows PCs being used by twenty-five
> children (say, five and six years old) all at the same

.....I can't even come up with a word horrific enough to apply to such a
situation.
You must be either a saint or a masochist.
If my troubles with my computers, and me being well-versed in their innards,
is anything typical, I shudder to think what a roomful of seven-year-olds(?)
could do with 25 of them....
You have my sympathies.

> Still, I have had some limited chances to use VPython
> in the lab; and the kids seem to like what they've
> seen so far. I'm hoping to use it for more instruction
> in solid geometry and computer graphics as time goes
> on.

Then perhaps you (and anyone, including your students) might find this
useful and/or fun, since it's pretty simple (written in my commented and
_sophomoric_ (read: 'beginner's') Python using the latest VPython (which has
the "scene.stereo='crosseyed'" keyword) and Python 2.4.1 (but it should run
on any back to v.2.3 or so).  If you don't have the latest VPython, you'll
have to go into the script and change scene.stereo='crosseyed' back to
scene.stereo='passive' (same as walleyed).

In the zip file is the script TVLiveST.py, and Kirby Urner's coords.py
(which is required for various reasons, is small, is useful, and is a decent
example of coordinate-transformation functions written in Python).
Just put both where VPython can find them at run time.

http://tetrahedraverse.com/tverse/engine/TVLiveST.zip

Use from VPython's Idle.  I have not tried it from the command line.
It's a very stripped down and simplified version of my much larger program
intended to explore a certain philosophical/geometric guess at what
'reality' (spacetime) actually is.
Certain deprecatory correspondents of mine call it "a ball-packer."  It lets
you put a number of balls into a larger ball, then allows you to shrink or
expand the larger ball, compressing the set of smaller ones.
To me, the balls represent repulsion-fields around dimensionless,
non-coalesceable points (I call them "pionts," to keep the math-language
police from my doorstep), but to you et.al, they might as well be rubber
balls being squashed into spherical containers too small to hold them.

I'm not sure this list is the proper place to put this, but then, I'm a
beginner and this might be a good example of a reasonably complex idea
presented in simple form, and my code is very (very) readable.
(If anyone has suggestions where else this might find use, please tell
me....)

But for you and the seven-year-olds, it might be fun 'cause they can make
the balls go crazy and can observe what happens when you squeeze 'em into
too tight a space.  I'm also curious to know if the thing even runs on other
machines than mine.  You can't, though, make any data entry errors (it asks
like, four simple questions), or the program will crash and need a restart.
Also, I stongly suggest keeping the number of balls somewhere under a couple
of hundred, and numbers below 13 will show relationships between
balls-in-sphere ("packing") that are geometrically educational.

Peace
JB
jb...@te...
Web: http://tetrahedraverse.com

Re: [Visualpython-users] Question about frame objects

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

This may be a feature rather than a bug after all, but at a minimum the 
documentation needs to be corrected.

There's a subtle connection to the way deletion of objects works in 
Visual. In Python itself, if an object no longer has a reference to it, 
that object is eligible for deletion (through periodic garbage 
collection). For example, suppose you write rec = recordobject(name, id, 
age) and then later say rec = 5. Now there is no longer any way to refer 
to the recordobject you had created, and Python can eventually get 
around to freeing up the memory occupied by the object. The way this 
works is that there is a reference count associated with every object, 
and if this count ever goes to zero, the object can be deleted. (As 
another example, if after creating the object labeled "rec" you said b = 
rec and c = rec, the reference count would be 3, and executing rec = 5 
would reduce the reference count on the original object to 2.)

In the Visual environment there's an additional reference count 
corresponding to the human viewer, if the object is visible. Suppose you 
say s = sphere(). Essentially, this humanly visible object has a 
reference count of two. If you say s = 5, the reference count on the 
sphere decrements to 1, not to zero, because there's a human still 
looking at the object. If instead of saying s = 5 you say s.visible = 0, 
the reference count also decrements to 1, not to zero (there's still the 
s reference to it), and later you can get the sphere back by saying 
s.visible = 1. If on the other hand you say s = 5 and then try to say 
s.visible = 0, you get an error because 5 doesn't have a visible 
attribute. This means that a visible object with no symbolic reference 
cannot be deleted (because a human is viewing it, and there's no way to 
make it invisible). The only way to delete a sphere from memory is to 
first make it invisible, then remove symbolic references to the object; 
this reduces the reference count to zero and makes the memory 
reclaimable by Python.

Associated with a frame (and a display) is an attribute "objects", which 
is a list only of the visible objects in that frame or display. The 
basic reason is that if this list also included invisible objects, the 
reference to that object in this list would essentially give an 
additional reference count to the object, adding even more complexity to 
this rather complex situation. And if somehow we all figure out how to 
define the behavior in such a way that making an object in a frame be 
invisible without removing it from the "objects" list, it's possible 
that this nonremoval would apply only if you created the object with a 
name, but it would be removed if you didn't give it a name. Yuck.

One possibility that occurs to me is that it might be possible to 
implement frame.visible = 0 which I think could be unambiguous: make the 
objects in this frame temporarily invisible not because they themselves 
have visible = 0 but because the frame they're in does. I note that 
currently something odd happens with this:

f = frame()
s = sphere(frame=f)
f.visible = 0
print f.objects
RunTimeError: boost::bad_weak_ptr

As a first step it seems like I should make it clear in the 
documentation that frame.objects and display.objects are lists solely of 
visible objects.

Comments and corrections are welcome!

Bruce Sherwood wrote:

> For completeness, I tried this on an old version of VPython (Python 
> 2.3 plus Visual from October 2003). Both in that old version and the 
> current one, when an object is made invisible it is also removed from 
> the display.objects and frame.objects lists. This seems like a design 
> flaw, since as you point out once the object has been removed from the 
> list you can't find it that way. You'd have to keep a copy of the list 
> before making anything invisible.
>
> I have a very dim recollection that this was supposed to be a feature, 
> not a bug, that if an object was invisible you didn't want to be told 
> about it while looking through the list of objects. Does anyone 
> remember anything about this? At the moment (admittedly it's late at 
> night, so I might be thinking fuzzily) it seems much better to keep 
> the invisible objects in the lists so that you can reference them 
> again through the list, as you tried to do. Looping through the list 
> you could easily skip objects that are invisible, if that's what you 
> want to do.
>
> Bruce Sherwood
>
> Jeremy Sachs wrote:
>
>> The VPython documentation says that the objects in a frame can be  
>> made "temporarily invisible" with the following:
>>
>> for obj in someframe.objects:
>>     obj.visible=0
>>
>> And that works, only not temporarily. For any other object, I can 
>> set  the "visible" property to 1 and that object will be drawn. I 
>> can't  get this to work with the contents of a frame. Am I 
>> overlooking  something? There are three labels in the frame, as well 
>> as more  typical objects, but I don't suspect them to be the source 
>> of the  problem. Could someone please offer a suggestion?
>>
>>     -Jeremy S.
>>
>>
>> -------------------------------------------------------
>> This SF.net email is sponsored by: Splunk Inc. Do you grep through 
>> log files
>> for problems?  Stop!  Download the new AJAX search engine that makes
>> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
>> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
>> _______________________________________________
>> Visualpython-users mailing list
>> Vis...@li...
>> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>
>
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through log 
> files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

Re: [Visualpython-users] Question about frame objects

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

For completeness, I tried this on an old version of VPython (Python 2.3 
plus Visual from October 2003). Both in that old version and the current 
one, when an object is made invisible it is also removed from the 
display.objects and frame.objects lists. This seems like a design flaw, 
since as you point out once the object has been removed from the list 
you can't find it that way. You'd have to keep a copy of the list before 
making anything invisible.

I have a very dim recollection that this was supposed to be a feature, 
not a bug, that if an object was invisible you didn't want to be told 
about it while looking through the list of objects. Does anyone remember 
anything about this? At the moment (admittedly it's late at night, so I 
might be thinking fuzzily) it seems much better to keep the invisible 
objects in the lists so that you can reference them again through the 
list, as you tried to do. Looping through the list you could easily skip 
objects that are invisible, if that's what you want to do.

Bruce Sherwood

Jeremy Sachs wrote:

> The VPython documentation says that the objects in a frame can be  
> made "temporarily invisible" with the following:
>
> for obj in someframe.objects:
>     obj.visible=0
>
> And that works, only not temporarily. For any other object, I can set  
> the "visible" property to 1 and that object will be drawn. I can't  
> get this to work with the contents of a frame. Am I overlooking  
> something? There are three labels in the frame, as well as more  
> typical objects, but I don't suspect them to be the source of the  
> problem. Could someone please offer a suggestion?
>
>     -Jeremy S.
>
>
> -------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc. Do you grep through log 
> files
> for problems?  Stop!  Download the new AJAX search engine that makes
> searching your log files as easy as surfing the  web.  DOWNLOAD SPLUNK!
> http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

[Visualpython-users] Question about frame objects

[Jeremy S. <rez...@ma...>]

The VPython documentation says that the objects in a frame can be  
made "temporarily invisible" with the following:

for obj in someframe.objects:
	obj.visible=0

And that works, only not temporarily. For any other object, I can set  
the "visible" property to 1 and that object will be drawn. I can't  
get this to work with the contents of a frame. Am I overlooking  
something? There are three labels in the frame, as well as more  
typical objects, but I don't suspect them to be the source of the  
problem. Could someone please offer a suggestion?

	-Jeremy S.