visualpython-users

[Visualpython-users] More wxPython progress

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

Today for the first time I was able to run all of the standard VPython
programs with a version of VPython based on wxPython. There's still
some polishing to be done before a release, but I'm delighted to have
gotten this far.

Remember that one thing this will lead to is a version that uses Cocoa
on the Mac and can therefore permit running on a 64-bit Python.
Another thing it should make possible is being able to put a 3D
graphics canvas in a window that also has native buttons, sliders,
etc., and with native pull-down menus.

Bruce Sherwood

Re: [Visualpython-users] Changing a graph

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

Perhaps this is what you're looking for:

from visual import *
from visual.graph import *
# From the VPython Help:
#    If you say g = gcurve(), g.gcurve is
#    a curve object used to represent the gcurve.
#    Every gdisplay has the attribute "display".
d = gdisplay()
g = gcurve()
g.plot(pos=(2,1))
g.plot(pos=(5,3))
d.display.mouse.getclick()
g.gcurve.pos = [(1,3), (4,1)]

Bruce Sherwood

On Fri, Nov 9, 2012 at 6:02 PM, Brian Stephanik
<bri...@gm...> wrote:
> I have a question on how to perfrom a specific task in VPython. I hope I'm
> asking the right list.
>
> I'm trying to get the visual.graph module to be able to dynamically update a
> curve. For example, I'd like to graph a function f(x) + c, where c is able
> to be manipulated by the user, perhaps via a slider control. I can't seem to
> get VPython to *change* a graph, only to draw new ones (it seems histograms
> are able to do this, but not the other plot types?). And the gcurve object
> doesn't seem to respond to setting .visible=False, thus allowing me to
> create a new one and re-draw.
>
> Thanks for considering,
>
> Brian
>
>
> Brian Stephanik
> Graduate Student
> Department of Physics
> University of Washington
> bs...@uw...

[Visualpython-users] Changing a graph

[Brian S. <bri...@gm...>]

I have a question on how to perfrom a specific task in VPython. I hope I'm
asking the right list.

I'm trying to get the visual.graph module to be able to dynamically update
a curve. For example, I'd like to graph a function f(x) + c, where c is
able to be manipulated by the user, perhaps via a slider control. I can't
seem to get VPython to *change* a graph, only to draw new ones (it seems
histograms are able to do this, but not the other plot types?). And the
gcurve object doesn't seem to respond to setting .visible=False, thus
allowing me to create a new one and re-draw.

Thanks for considering,

Brian


Brian Stephanik
Graduate Student
Department of Physics
University of Washington
bs...@uw...

[Visualpython-users] wxPython progress

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

Progress report on basing VPython on wxPython: All objects display, in
multiple windows, and all mouse interactions work. The major known
issues not yet addressed are GetProcAddress, a platform-dependent
function for invoking extensions to OpenGL, and font issues. None of
this is in a public repository yet.

Bruce Sherwood

Re: [Visualpython-users] Progress toward wxPython

[C A. R. <an...@xt...>]

On Sat, Oct 20, 2012 at 9:47 PM, Mark Adam <dre...@gm...> wrote:
> On Sat, Oct 20, 2012 at 7:23 PM, Bruce Sherwood <Bru...@nc...> wrote:
>
>> As for "VPython attracts young programmers", I've been disappointed
>> that Brandmeyer was the only new person, young or old, to get deeply
>> involved with VPython development after its creation.
>
> I meant that 3-d graphics, in the easy way that vpython makes it, adds
> a very cool "gee-wiz" factor that is hard to beat.  Young programmers
> eat that stuff up, and it acts as a magnet that attracts more
> development.

perhaps a bit random...

vpython is actually the reason i forced myself to learn python.  i was
indeed fascinated by the simplicity and power of it all, and my foray
was a re-implementation of [ruby] gltail that i sadly never finished,
albeit learned a ton... been lurking on the list ever since...
something like 3-4 years or so.

i suppose i'm not suuuuper young @ 25yo; i've been a full-time
developer for ~5-6yrs -- the last two purely python -- i credit
portions of the latter to vpython's alluring brilliance, and the rest
to python's own inherent magnificence.

sadly i have not contributed much of anything concrete, due mostly to
the ever-lasting-excuse "lack-of-time" and "other-projects" and [...],
but i recently gave a demo of vpython for ~45 other developers
(Perl/PHP/JS primarily) at work that was extremely well received --
spheres orbiting a "gravity well" -- where each sphere represents (and
responds+morphs to) events/messages occurring on the company -wide
message queue (rabbitmq)... so after little more than ~200 lines of
glue and glitz, i demo'ed a real-time visualization of human
"busy-ness"... the events in question were ~600 call center agent
status changes (hold/waiting/busy/incoming/cool-down/etc) from a
facility several hundred miles away.

needless to say, and despite it's obvious simplicity and/or lack of
any real practical use, it still irradiated onlookers with "very cool
`gee-wiz` factor" and piqued the interest of everyone around --
non-developers alike -- and ultimately led to some
chatter/buzzing/exploring the possibilities.

apologies on the length; hopefully a little success story at the very
least!  even my 3yo son asks me to "play the balls" for him pretty
often still, and doing so gets many-a-"wows" and "that's cool dad"
sent my way :)

visual-python FTW!

-- 

C Anthony

Re: [Visualpython-users] Progress toward wxPython

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

Well, I may be completely oblivious and ignorant, but I really can't
imagine that there was some "split" involving VPython. The Python
developers rather quickly on the scale of things decided to make 1/2
be 0.5, for their own internal reasons. I think that the change had
little to do with the request from someone (me) who at that time had
no standing whatsoever, for the sake of something called VPython,
which at the time had close to zero users and was hardly known. It was
impossible for Python to make an immediate change, due to backward
compatibility issues. In my view that community has done an admirable
job in dealing with this issue, even though it has taken much longer
than one would prefer.

There could have been some kind of split between integer-oriented
computer scientists and floating-point-oriented computational
scientists, but about the major development numpy (and its
predecessors), not the minor development VPython. One could make
cogent arguments for numpy having been part of Python. Despite that,
there is a flourishing community of scientific Python users, the most
visible component being scipy.org and the Sage project. In recent
years there have been two whole issues of the journal "Computers in
Science and Engineering" devoted to Python. A few years ago one of the
astrophysics groups at NCSU abandoned the numerical package they had
been using and switched to Python. Etc. All of which says that the
computational modeling folk were not pushed away from Python by some
hypothesized resistance from Guido and fellow developers.

Bruce Sherwood

Re: [Visualpython-users] Progress toward wxPython

[Mark A. <dre...@gm...>]

On Sat, Oct 20, 2012 at 7:23 PM, Bruce Sherwood <Bru...@nc...> wrote:
> Soon it became evident that a significant stumbling block was the fact
> that in Python, as in so many languages (but not JavaScript) 1/2 was
> 0, not 0.5. This caused lots of trouble for our physics students, so I
> proposed to the Python community that 1/2 be 0.5 instead of 0. That
> was a trigger for lots of debate among Python developers, who
> eventually found that they had their own reasons for making the
> change.

Thanks for the recollection.  The reason I said it was a significant
break, is that with that debate/faction, [my sense was] a fork between
physicists, who were looking at high-level programming languages as
both a pedagogical tool and modeling tool (beyond its historical use
as a calculating tool), and the computer science crowd, who were
looking at languages from a completely different light within both CS
theory and programming language design (in which Python was a recent
and novel contribution), occurred because of an unresolved debate
about the importance of floating point (for the Phys crowd) and
historical "prejudices" in comp science crowd about having unambiguous
"round numbers".

To me, this was a bit split, and although it was relegated to the
__future__ and is the default in python3, the "future", if you will,
still hasn't seemed to have happened yet.

> There has never been a "VPython development community".

I understand that it has been small, but I don't know if you're aware
how much silent support you guys had in the simulation and modeling
crowd.  Though they weren't participating directly in vpython
development, they were waiting in the background -- hedging for a
major language adoption, so that they could [re-]invest their
"holdings", so to speak.   Much like a bunch of financial investors
eyeing at a new country which is evaluating a choice at instituting a
democratic, free-market system.  Judging from your message, I don't
think you ever saw that, but yet I know that it was there.  I think
Guido sensed it, but in the end his computer science bias simply won.
With that win, many turned away.

> So the "VPython development community" has fluctuated between 1 and 2
> people, and this infinitesimal group never "receded from the
> python-dev community", of which it was never a part.

This is the source of my lament, Bruce -- it was on the verge of
becoming a major synthesis and collaboration between two major groups
(comp sci and physics/modeling).

> As for "VPython attracts young programmers", I've been disappointed
> that Brandmeyer was the only new person, young or old, to get deeply
> involved with VPython development after its creation.

I meant that 3-d graphics, in the easy way that vpython makes it, adds
a very cool "gee-wiz" factor that is hard to beat.  Young programmers
eat that stuff up, and it acts as a magnet that attracts more
development.

> I don't understand your pessimism, that one must abandon multiplatform
> or speed or API.

I mean that the OS carries its *own* event model and sits between
python user-space and the hardware.   It has its *own* ideas of how
I/O should be scheduled, managed, and accessed (that is the *business*
of the OS after all!).  This makes it difficult to be multi-platform
without sacrificing either raw speed or consistent API abstraction
(two ends of the hardware <--> user "stack").

> As for a unified operating environment, I'll point to GlowScript
> (glowscript.org), which is very similar to VPython but runs in a
> browser. It is based on Javascript (or optionally CoffeeScript) and
> uses in place of OpenGL (used by VPython) the similar 3D graphics
> library WebGL, which is part of current browsers. GlowScript now has
> capabilities roughly comparable to VPython. Not coincidentally, it has
> been built by David Scherer and me, though Scherer has not been able
> to work on it for some months, being deeply involved in his new
> company (foundationdb.com). It has been a great joy to work in an
> environment where thanks to being browser-based it was truly trivial
> for GlowScript to work automatically on Windows, Mac, and Linux.

I've been following your developments with glowscript and with all the
hype of HTML5 and WebGL.  I like those experiments, because I think it
keeps vpython in the public consciousness to some degree, but I really
think WebGL will go the way of VRML (remember that?); i.e. a powerful
tool that no one knows how to exploit properly.

...Which bring me to the (real) point underlying all of this.  As you
might remember, I was at the Santa Fe Complex, trying to develop a
tool to make this nascent phenomenon of "hackerspaces" work -- a tool
to link people and projects together in a visual way, solving once and
for all the scaling problem that happens when you get to about a 1000
objects.   Slashdot, digg, del.icio.us, etc. -- all have suffered from
the "paucity of dimensionality" that HTML is.

Current HTML offers about 2.3 (fractal dimensions) of representing
linked data (i.e. "hypertext").  VPython (or WebGL, in theory), could
break the web about of the 2-d box and create a 3d *Presentation*
layer for the WWW allowing the visual cortex to make relationships
between data rather than hand-crafting RDF.  I call this Internet II,
and if I could just get the event-model understood in VPython, I would
have a working demo in short order, but that has been driving me up
the wall because the paradigm between my "python self" and my "vpython
self" is currently dissociated for reasons I've been alluding to.

Anyway, you don't need to break time away from vpython development,
but I do think it would re-vamp the web out of its current suburbia
and re-ignite the creative economy.

Thanks for your time,

MarkJ
Gothenburg, Nebraska

Re: [Visualpython-users] Progress toward wxPython

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

I can correct the history. David Scherer created VPython in the spring
of 2000 while a sophomore at Carnegie Mellon. The year before, he had
taken intro physics from Ruth Chabay and me (see
matterandinteractions.org), in which we had students write programs in
the 2D programming language cT I had created. Scherer proposed a much
improved 3D programming environment which, amid lots of discussion
with Chabay and me, he implemented.

Soon it became evident that a significant stumbling block was the fact
that in Python, as in so many languages (but not JavaScript) 1/2 was
0, not 0.5. This caused lots of trouble for our physics students, so I
proposed to the Python community that 1/2 be 0.5 instead of 0. That
was a trigger for lots of debate among Python developers, who
eventually found that they had their own reasons for making the
change.

There has never been a "VPython development community". in 2001
Scherer went off and founded a successful business. In 2002 I moved to
North Carolina State University, where an undergraduate student,
Jonathan Brandmeyer, got interested and made large contributions to
the further development and maintenance of VPython until he graduated.
In 2008 VPython needed significant work, and quite fortuitously
Scherer, between building companies, volunteered to work again on
VPython, and for about a year we collaborated on what became VPython
5.0 before he started a second company. All during these 12 years I
have been involved in development and maintenance, and for the past 4
years I've been the only major developer. (From time to time various
people have contributed in important but relatively small-scale ways.)

So the "VPython development community" has fluctuated between 1 and 2
people, and this infinitesimal group never "receded from the
python-dev community", of which it was never a part.

As for "VPython attracts young programmers", I've been disappointed
that Brandmeyer was the only new person, young or old, to get deeply
involved with VPython development after its creation.

I don't understand your pessimism, that one must abandon multiplatform
or speed or API. I would certainly like to see higher Python execution
speed, and I realize there are efforts under way. The new VPython will
certainly continue to be multiplatform, with the same API except for
rate being obligatory rather than optional.

As for a unified operating environment, I'll point to GlowScript
(glowscript.org), which is very similar to VPython but runs in a
browser. It is based on Javascript (or optionally CoffeeScript) and
uses in place of OpenGL (used by VPython) the similar 3D graphics
library WebGL, which is part of current browsers. GlowScript now has
capabilities roughly comparable to VPython. Not coincidentally, it has
been built by David Scherer and me, though Scherer has not been able
to work on it for some months, being deeply involved in his new
company (foundationdb.com). It has been a great joy to work in an
environment where thanks to being browser-based it was truly trivial
for GlowScript to work automatically on Windows, Mac, and Linux.

There was a recent event quite parallel to the 1/2 = 0.5 issue. In
JavaScript you cube a value x by writing Math.pow(x,3). Yuck. The
CoffeeScript developers had been considering whether to implement
x**3, and the additional arguments I presented pushed them over the
edge. There is a new CoffeeScript compiler to be released soon,
CoffeeScript Redux, which implements x**3. Here is a link to that
discussion:

   https://github.com/jashkenas/coffee-script/pull/2026

Bruce Sherwood

Re: [Visualpython-users] Progress toward wxPython

[Mark A. <dre...@gm...>]

On Fri, Oct 19, 2012 at 11:03 PM, Bruce Sherwood
<Bru...@nc...> wrote:
> I'm curious: I don't know what you're referring to when you say that
> the problem is Guido not accepting "visual as part of the standard
> library". What old debate are you referring to? (Incidentally, Guido
> has always said nice things to me about visual.)

I'll try to look it up, but is was about float division.  It seems
trivial but I remember afterwards how a whole segment of the python
community seem to disappear.   That is, before the faction VPython and
Python were in the same group, but afterwards VPython receded from the
python-dev community.

> I agree that making visual a part of the standard library would make
> sense. But the problem I'm trying to address wouldn't have been helped
> by visual being in the standard library -- there would still be the
> serious Carbon/Cocoa problem to be solved.

Yes, but I think the way VPython attracts young programmers, that
there would be a whole support network.

> Incidentally, you might be mildly amused by the "fancy footwork" I
> alluded to. Briefly, when the user program invokes the visual module,
> I set up the interact loop (Cocoa on the Mac), then I import the
> user's program! This makes Cocoa the primary thread (and only thread),
> which is a requirement of Cocoa. This also means that any user
> statements preceding the visual import will be executed twice, which
> is unlikely to be a problem (and can be documented), and no statements
> in the visual module will be executed twice because once a module is
> imported in a session, executable statements are not re-executed by a
> later import in the same session.

Thanks, that is interesting.  I have been debating some of the
abstract parts of these issues in the thread on event loops and
asynchronous support in Python (happening recently in the python-ideas
list with Guido).  I think one of these has to be given up
[multi-platform, speed, abstracted (uniform) API] -- at least until
there's a unified pythonOS that is also a WebOS...

Mark

[Visualpython-users] Need help on using VPython to model an electrical circuit: Flying-Adder frequency synthesizer

[liming x. <lm...@gm...>]

Dear All:

My name is Liming Xiu. I am a professional in the field of VLSI
circuit design.  I am the inventor of an important frequency synthesis
architecture: Flying-Adder frequency synthesis architecture.  You can
google  seach this technology by using key word “Flying-Adder
frequency synthesis architecture” or “Flying-Adder frequency PLL”.
This invention is summarized in my newly published book:

“Nanometer Frequency Synthesis beyond the Phase Locked Loop”

http://www.wiley.com/WileyCDA/Section/id-WILEY2_SEARCH_RESULT.html?query=xiu


One of the key components in this technology is the Flying-Adder
circuit. Although this circuit was invented in later 1990 and has been
used in commercial products for over a decade and generates over one
billion dollar revenue, the circuit itself is not familiar to many
circuit designers. The key reason is that this circuit is very
complex, it is hard to be understood.  Thus, I want to use VPython to
illustrate the working principle of this circuit so that designers can
see the working of this circuit visually.

I have decent programming experience in C and Perl, but not in Object
Oriented Program such as Python and VPython.  In the past few months,
I have studied the Python and VPython by reading books and studying
examples. But when I start to model this Flying-Adder circuit, I am
feeling the pain now :-)

I wonder if anyone in this mail list could help me on this project?
This project is to model a real circuit that has been used in numerous
commercial VLSI chips.  The details can be found in chapter four of
the above mentioned book.

This project is a 2D programming. Thus, it should be a simple case for
people who are familiar with VPython. If you are willing to help me, I
will not ask too much time from you. May be  ~ 30 minutes every a few
days. The circuit will be explained step by step and the code will be
constructed step by step, accordingly.

Please send me email,  lm...@gm...,  if you are interested in helping me.

Thanks in advance

Liming Xiu

By the way, below is the code that is built by Bruce Sherwood for me
(thanks, Bruce). It is the very first part of this project.


------------------------------------------------------------------------------------

from __future__ import division
from visual import *

N = 8
# fov = field of view; small fov means camera far from scene
display(width=1200, height=640, range=8, fov=0.01,
        title='Flying-Adder Syntheszier Input Signals',
background=color.gray(0.5) )

pulses = []

k = 5
T = 2*pi/k
dx = T/N

colors = [color.red, color.green, color.blue,
          color.yellow, color.cyan, color.magenta,color.orange, color.white]

for i in range(N):
    pulses.append(curve( x = arange(-10,10,0.01),radius=0.04,color=colors[i]))
    # multiply by 0.99 to guard against possible ceil glitch; -0.25 to
center the pulse vertically
    pulses[i].y = 0.5*ceil(0.99*sin( k*(pulses[i].x+i*dx)))+N/2-i*N/8-0.75

t = 0
dt = T/800
while True:
    rate(200)
    for p in pulses:
        p.x += dt
    t += dt
    if t >= T:
        t = 0
        for p in pulses:
            p.x -= T

Re: [Visualpython-users] Move a clock pulse train, please help

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

I leave this extension to you. You've already structured your program
appropriately by starting to create a list of displays. Just create
all 8 displays, and in the animation loop loop over these displays to
update all 8 pulse trains (displaced as you say).

Bruce Sherwood

On Fri, Oct 19, 2012 at 10:35 AM, liming xiu <lm...@gm...> wrote:
> Dear Bruce:
>
> Thanks.  It looks great!
>
> Can I ask you one more favor:
>
> I want to create 8 of these clock pulse trains, from screen top to
> bottom ( the screen can be made bigger).
>
> 1. All the 8 pulse trains have save frequency (same T).
> 2. Time-wise, each pulse trains is delayed from its previous one by
> (1/8)T. In other words, the second one is (1/8)T behind the first one,
> the third one is  (1/8)T behind the second one.
> 3. They all move from left to right.
>
> Can you help me on this?
>
> Thanks in advance!
>
>
>
>
>
> On Fri, Oct 19, 2012 at 11:14 AM, Bruce Sherwood
> <Bru...@nc...> wrote:
>> That's a clever way to make a pulse train; I wouldn't have thought of
>> using the math ceil function. Here's one way to animate the pulse
>> train, moving to the right. I set the range to 9 so that the pulses
>> fill the screen. I move the display's center to the left until one
>> period has elapsed, when I reset the center to the origin:
>>
>> from visual import *
>>
>> g = []
>> g.append(display(x = 0, y = 100, width=1000, height=400, range=9))
>>
>> g[0].title="Second try"
>>
>> k = 5
>> T = 2*pi/k
>> c = curve( x = arange(-10,10,0.01),
>>         display=g[0],radius=0.07,color=color.yellow  ) # Draw a pulse train
>> c.y = ceil(sin( k*c.x ))
>>
>> t = 0
>> dt = T/20
>> while True:
>>     rate(100)
>>     g[0].center.x -= dt
>>     t += dt
>>     if t >= T:
>>         g[0].center.x = 0
>>         t = 0
>>
>> You might wish to disable userspin and userzoom to prevent the viewer
>> from messing up the display.
>>
>> Just in case you hadn't noticed it, I'll comment that in your original
>> program you don't need a loop at the end to keep the display alive.
>> When you come to the end of a VPython program, the display remains on
>> the screen and you can zoom and rotate.
>>
>> Bruce Sherwood
>>
>> On Fri, Oct 19, 2012 at 9:39 AM, liming xiu <lm...@gm...> wrote:
>>> Hi,
>>>
>>> I am new to VPython. I want to use this tool to do a project for my work.
>>>
>>> I create a clock pulse train using the few lines below.
>>>
>>> ----------------------------------------------------
>>> from visual import *
>>>
>>> g = []
>>> g.append(display(x = 0, y = 100, width=1000, height=400))
>>>
>>> g[0].title="First try"
>>>
>>> c = curve( x = arange(-10,10,0.01),
>>> display=g[0],radius=0.07,color=color.yellow  ) # Draw a helix
>>> c.y = ceil(sin( 5.0*c.x ))
>>>
>>> while True:
>>>     rate(5)

[Visualpython-users] Progress toward wxPython

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

Some time ago I mentioned my intention to build a version of VPython
that uses wxPython to create the window, establish an OpenGL context
in that window, and handle keyboard and mouse events. This would make
it possible to discard the existing three platform-specific C++
components for dealing with these tasks (Windows, Macintosh, Linux),
because wxPython, based on wxWidgets, is platform-independent.

The need for this is somewhat urgent, because the Mac version of
VPython is based on the Carbon framework, which is no longer fully
supported. In particular, Carbon cannot be used with 64-bit
applications (one must use Cocoa), which means that at the moment it
is impossible to build a native-Mac (not Unix) version of VPython for
the Mac that can run with a 64-bit version of Python, and until very
recently there seemed to be no way to base VPython on Cocoa, for
technical reasons (see below).

I'm pleased to say that I've managed to get a basic wxPython-based
version to work, with the platform-specific C++ components replaced by
pure Python code. There are many remaining details to deal with, but
I'm able to display an animation, and to rotate and zoom the scene.
Progress.

Looking ahead, here are some comments about what a wxPython-based
version of VPython will look like.

First, it is likely that all animations will have to contain a rate or
sleep statement. This is due to a very technical issue. Cocoa requires
that Cocoa itself be the primary thread, whereas the current VPython
makes Carbon be the secondary thread. To turn this architecture
inside-out required some fancy footwork, and the summary statement is
that the visual module and your user code are likely to be in a single
thread, with no multithreading. This simplifies the VPython
architecture, but requires the user to use rate (or sleep) to allow
VPython to render the scene periodically. Without a rate statement in
an animation loop, nothing will appear on the screen until you exit
the loop, and then you'll see only the final state of the display. I
judge that the need for rate isn't serious, because almost all
animations necessarily contain a rate statement anyway, to make the
animation run at a roughly machine-independent speed. Experience with
GlowScript (glowscript.org), which also requires use of rate (because
JavaScript doesn't have threads), suggests that requiring a rate
statement isn't a significant burden.

Second, it should be possible to place a 3D animation anywhere in the
window, place other wxPython widgets in the same window (e.g. buttons,
sliders, text, etc.), and create normal pull-down menus for the
window. This suggests that VPython should have two new objects, a
"window" object (to hold menus and the various widgets), and a
"canvas" object (to provide the OpenGL context for the 3D animations.
The existing VPython "display" object would remain as a device that
creates a "window" object and places a "canvas" in the window in such
a way as to fill the window, as is the case currently.

Third, there currently does not exist a version of wxPython for Python
3.x, just 2.x, but on May 24, 2012, there was news that this is
forthcoming:

   http://www.blog.pythonlibrary.org/2012/05/24/wxpython-for-python-3-is-almost-here/

Fourth, presumably the new VPython will have the version number 6.00,
to emphasize a change in the definition of VPython, namely the
necessity to use rate in animations.

Bruce Sherwood

Re: [Visualpython-users] Move a clock pulse train, please help

[liming x. <lm...@gm...>]

Dear Bruce:

Thanks.  It looks great!

Can I ask you one more favor:

I want to create 8 of these clock pulse trains, from screen top to
bottom ( the screen can be made bigger).

1. All the 8 pulse trains have save frequency (same T).
2. Time-wise, each pulse trains is delayed from its previous one by
(1/8)T. In other words, the second one is (1/8)T behind the first one,
the third one is  (1/8)T behind the second one.
3. They all move from left to right.

Can you help me on this?

Thanks in advance!





On Fri, Oct 19, 2012 at 11:14 AM, Bruce Sherwood
<Bru...@nc...> wrote:
> That's a clever way to make a pulse train; I wouldn't have thought of
> using the math ceil function. Here's one way to animate the pulse
> train, moving to the right. I set the range to 9 so that the pulses
> fill the screen. I move the display's center to the left until one
> period has elapsed, when I reset the center to the origin:
>
> from visual import *
>
> g = []
> g.append(display(x = 0, y = 100, width=1000, height=400, range=9))
>
> g[0].title="Second try"
>
> k = 5
> T = 2*pi/k
> c = curve( x = arange(-10,10,0.01),
>         display=g[0],radius=0.07,color=color.yellow  ) # Draw a pulse train
> c.y = ceil(sin( k*c.x ))
>
> t = 0
> dt = T/20
> while True:
>     rate(100)
>     g[0].center.x -= dt
>     t += dt
>     if t >= T:
>         g[0].center.x = 0
>         t = 0
>
> You might wish to disable userspin and userzoom to prevent the viewer
> from messing up the display.
>
> Just in case you hadn't noticed it, I'll comment that in your original
> program you don't need a loop at the end to keep the display alive.
> When you come to the end of a VPython program, the display remains on
> the screen and you can zoom and rotate.
>
> Bruce Sherwood
>
> On Fri, Oct 19, 2012 at 9:39 AM, liming xiu <lm...@gm...> wrote:
>> Hi,
>>
>> I am new to VPython. I want to use this tool to do a project for my work.
>>
>> I create a clock pulse train using the few lines below.
>>
>> ----------------------------------------------------
>> from visual import *
>>
>> g = []
>> g.append(display(x = 0, y = 100, width=1000, height=400))
>>
>> g[0].title="First try"
>>
>> c = curve( x = arange(-10,10,0.01),
>> display=g[0],radius=0.07,color=color.yellow  ) # Draw a helix
>> c.y = ceil(sin( 5.0*c.x ))
>>
>> while True:
>>     rate(5)

Re: [Visualpython-users] Move a clock pulse train, please help

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

That's a clever way to make a pulse train; I wouldn't have thought of
using the math ceil function. Here's one way to animate the pulse
train, moving to the right. I set the range to 9 so that the pulses
fill the screen. I move the display's center to the left until one
period has elapsed, when I reset the center to the origin:

from visual import *

g = []
g.append(display(x = 0, y = 100, width=1000, height=400, range=9))

g[0].title="Second try"

k = 5
T = 2*pi/k
c = curve( x = arange(-10,10,0.01),
        display=g[0],radius=0.07,color=color.yellow  ) # Draw a pulse train
c.y = ceil(sin( k*c.x ))

t = 0
dt = T/20
while True:
    rate(100)
    g[0].center.x -= dt
    t += dt
    if t >= T:
        g[0].center.x = 0
        t = 0

You might wish to disable userspin and userzoom to prevent the viewer
from messing up the display.

Just in case you hadn't noticed it, I'll comment that in your original
program you don't need a loop at the end to keep the display alive.
When you come to the end of a VPython program, the display remains on
the screen and you can zoom and rotate.

Bruce Sherwood

On Fri, Oct 19, 2012 at 9:39 AM, liming xiu <lm...@gm...> wrote:
> Hi,
>
> I am new to VPython. I want to use this tool to do a project for my work.
>
> I create a clock pulse train using the few lines below.
>
> ----------------------------------------------------
> from visual import *
>
> g = []
> g.append(display(x = 0, y = 100, width=1000, height=400))
>
> g[0].title="First try"
>
> c = curve( x = arange(-10,10,0.01),
> display=g[0],radius=0.07,color=color.yellow  ) # Draw a helix
> c.y = ceil(sin( 5.0*c.x ))
>
> while True:
>     rate(5)

[Visualpython-users] Move a clock pulse train, please help

[liming x. <lm...@gm...>]

Hi,

I am new to VPython. I want to use this tool to do a project for my work.

I create a clock pulse train using the few lines below.

----------------------------------------------------
from visual import *

g = []
g.append(display(x = 0, y = 100, width=1000, height=400))

g[0].title="First try"

c = curve( x = arange(-10,10,0.01),
display=g[0],radius=0.07,color=color.yellow  ) # Draw a helix
c.y = ceil(sin( 5.0*c.x ))

while True:
    rate(5)

-----------------------------------------------------

Now I want to make the pulse train moving, from left to right,
continuously. The points disapper from the right, then emerge from the
left, ...


Can someone help me?

Thanks in advance.

Re: [Visualpython-users] Cannot install Vpython on win7 64bit

[Kevin K. <ka...@so...>]

Although I don't have a Windows machine, and so can't check that the
executables are functional, they are certainly accessible from the
links at http://www.lfd.uci.edu/~gohlke/pythonlibs/#vpython

If you are having trouble with the downloads from there, the problem
is most likely at your end, and getting yet another link is not likely
to help you much.

Re: [Visualpython-users] Cannot install Vpython on win7 64bit

[Osemeka O. <aba...@gm...>]

Hi Bruce and Gary,
Thanks for replying. The links in your replies, however, are basically
the same on the vpython website and they all give me the same
results-->

Using Opera:
                                Connection closed by remote server
                    Check that the address is spelled correctly, or
try searching for the site.
Using Google Chrome:
                       Error 324 (net::ERR_EMPTY_RESPONSE): The server
closed the connection
                       without sending any data.

It was also unsuccessful using internet explorer. It seems that link
is the only way to get those files. could someone please upload it to
a file sharing site (like mediafire for instance) so I could get to
it? would that be okay?

Thanks
Abasiemeka

On Tue, Oct 16, 2012 at 3:44 PM, Bruce Sherwood <Bru...@nc...> wrote:
> The link on the vpython.org Windows download page works for me. It's
> basically the same as http://www.lfd.uci.edu/~gohlke/pythonlibs/, but
> in the form http://www.lfd.uci.edu/~gohlke/pythonlibs/#vpython which
> takes you directly to the VPython installers.
>
> Bruce Sherwood
>
> On Tue, Oct 16, 2012 at 3:47 AM, gary ruben <gr...@bi...> wrote:
>> Wow, I hadn't realised Christoph had successfully built VPython for
>> 64bit Windows until I read this, so a big thanks as I've been unable
>> to run VPython for a couple of years. Here are his packages and
>> VPython works well:
>> http://www.lfd.uci.edu/~gohlke/pythonlibs/
>>
>> Gary R
>>
>> On 16 October 2012 19:26, Osemeka Osuagwu <aba...@gm...> wrote:
>>> Hello all,
>>> Please is there a standalone installer for vpython for 64bit windows
>>> 7? I've not been able to start using vpython because I cant even get
>>> it on my system. The link on the Vpython website to Christopher
>>> Gohlke's 64bit package is broken. Please assist me.
>>>
>>> --Abasiemeka
>>>
>>> ------------------------------------------------------------------------------
>>> Don't let slow site performance ruin your business. Deploy New Relic APM
>>> Deploy New Relic app performance management and know exactly
>>> what is happening inside your Ruby, Python, PHP, Java, and .NET app
>>> Try New Relic at no cost today and get our sweet Data Nerd shirt too!
>>> http://p.sf.net/sfu/newrelic-dev2dev
>>> _______________________________________________
>>> Visualpython-users mailing list
>>> Vis...@li...
>>> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>>
>> ------------------------------------------------------------------------------
>> Don't let slow site performance ruin your business. Deploy New Relic APM
>> Deploy New Relic app performance management and know exactly
>> what is happening inside your Ruby, Python, PHP, Java, and .NET app
>> Try New Relic at no cost today and get our sweet Data Nerd shirt too!
>> http://p.sf.net/sfu/newrelic-dev2dev
>> _______________________________________________
>> Visualpython-users mailing list
>> Vis...@li...
>> https://lists.sourceforge.net/lists/listinfo/visualpython-users

Re: [Visualpython-users] Cannot install Vpython on win7 64bit

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

The link on the vpython.org Windows download page works for me. It's
basically the same as http://www.lfd.uci.edu/~gohlke/pythonlibs/, but
in the form http://www.lfd.uci.edu/~gohlke/pythonlibs/#vpython which
takes you directly to the VPython installers.

Bruce Sherwood

On Tue, Oct 16, 2012 at 3:47 AM, gary ruben <gr...@bi...> wrote:
> Wow, I hadn't realised Christoph had successfully built VPython for
> 64bit Windows until I read this, so a big thanks as I've been unable
> to run VPython for a couple of years. Here are his packages and
> VPython works well:
> http://www.lfd.uci.edu/~gohlke/pythonlibs/
>
> Gary R
>
> On 16 October 2012 19:26, Osemeka Osuagwu <aba...@gm...> wrote:
>> Hello all,
>> Please is there a standalone installer for vpython for 64bit windows
>> 7? I've not been able to start using vpython because I cant even get
>> it on my system. The link on the Vpython website to Christopher
>> Gohlke's 64bit package is broken. Please assist me.
>>
>> --Abasiemeka
>>
>> ------------------------------------------------------------------------------
>> Don't let slow site performance ruin your business. Deploy New Relic APM
>> Deploy New Relic app performance management and know exactly
>> what is happening inside your Ruby, Python, PHP, Java, and .NET app
>> Try New Relic at no cost today and get our sweet Data Nerd shirt too!
>> http://p.sf.net/sfu/newrelic-dev2dev
>> _______________________________________________
>> Visualpython-users mailing list
>> Vis...@li...
>> https://lists.sourceforge.net/lists/listinfo/visualpython-users
>
> ------------------------------------------------------------------------------
> Don't let slow site performance ruin your business. Deploy New Relic APM
> Deploy New Relic app performance management and know exactly
> what is happening inside your Ruby, Python, PHP, Java, and .NET app
> Try New Relic at no cost today and get our sweet Data Nerd shirt too!
> http://p.sf.net/sfu/newrelic-dev2dev
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

Re: [Visualpython-users] Cannot install Vpython on win7 64bit

[gary r. <gr...@bi...>]

Wow, I hadn't realised Christoph had successfully built VPython for
64bit Windows until I read this, so a big thanks as I've been unable
to run VPython for a couple of years. Here are his packages and
VPython works well:
http://www.lfd.uci.edu/~gohlke/pythonlibs/

Gary R

On 16 October 2012 19:26, Osemeka Osuagwu <aba...@gm...> wrote:
> Hello all,
> Please is there a standalone installer for vpython for 64bit windows
> 7? I've not been able to start using vpython because I cant even get
> it on my system. The link on the Vpython website to Christopher
> Gohlke's 64bit package is broken. Please assist me.
>
> --Abasiemeka
>
> ------------------------------------------------------------------------------
> Don't let slow site performance ruin your business. Deploy New Relic APM
> Deploy New Relic app performance management and know exactly
> what is happening inside your Ruby, Python, PHP, Java, and .NET app
> Try New Relic at no cost today and get our sweet Data Nerd shirt too!
> http://p.sf.net/sfu/newrelic-dev2dev
> _______________________________________________
> Visualpython-users mailing list
> Vis...@li...
> https://lists.sourceforge.net/lists/listinfo/visualpython-users

[Visualpython-users] Cannot install Vpython on win7 64bit

[Osemeka O. <aba...@gm...>]

Hello all,
Please is there a standalone installer for vpython for 64bit windows
7? I've not been able to start using vpython because I cant even get
it on my system. The link on the Vpython website to Christopher
Gohlke's 64bit package is broken. Please assist me.

--Abasiemeka

Re: [Visualpython-users] Uniform scaling with gdisplay

[Poul R. <Pou...@sk...>]

Oh, yes, I'm sorry, I missed a 'g'  in gcurve!

Poul Riis



from time import *
from math import *
import visual.graph as visualgraph


spiralgraph=visualgraph.gdisplay(title='Spiral', ytitle='x', xtitle='y',
                                 x=0, y=0,
                                 width=800, height=800,
                                 foreground=visualgraph.color.black,
                                 background=visualgraph.color.white)
spiralplot =
visualgraph.curve(color=visualgraph.color.red,display=spiralgraph)
spiralplot.plot(pos=(-15,-15))
spiralplot.plot(pos=(15,-15))
spiralplot.plot(pos=(15,15))
spiralplot.plot(pos=(-15,15))
spiralplot.plot(pos=(-15,-15))

for i in range(0,3600):
    t=pi*i/360
    x=t*cos(t)
    y=t*sin(t)
    spiralplot.plot(pos=(x,y))
    sleep(0.001)

Re: [Visualpython-users] Uniform scaling with gdisplay

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

What did you change? That is, what do you mean by "now"? Presumably
you didn't get such a very strange message before making some change.
Maybe you need to reinstall visual?

Bruce Sherwood

On Sun, Oct 14, 2012 at 12:32 PM, Poul Riis <Pou...@sk...> wrote:
> Even worse now:
>
> Running the program below now results in the following error message:
>
> Traceback (most recent call last):
>  File "C:\pr\python\spiral.py", line 11
>    spiralplot =
> visualgraph.curve(color=visualgraph.crayola.magenta,display=spiralgraph)
>  File "C:\Python32\lib\site-packages\vis\primitives.py", line 82, in
> __init__
>    if not _other: self.init_defaults(keywords)
>  File "C:\Python32\lib\site-packages\vis\primitives.py", line 175, in
> init_defaults
>    self.material = self.display.material
> AttributeError: 'gdisplay' object has no attribute 'material'
>
>
>
>
>
> import visual.graph as visualgraph
> from time import *
> from math import *
>
> spiralgraph=visualgraph.gdisplay(title='Spiral', ytitle='x', xtitle='y',
>                                 x=0, y=0,
>                                 width=800, height=800,
>                                 foreground=visualgraph.color.black,
>                                 background=visualgraph.color.white)
> spiralplot =
> visualgraph.curve(color=visualgraph.crayola.magenta,display=spiralgraph)
> spiralplot.plot(pos=(-15,-15))
> spiralplot.plot(pos=(15,-15))
> spiralplot.plot(pos=(15,15))
> spiralplot.plot(pos=(-15,15))
> spiralplot.plot(pos=(-15,-15))
> for i in range(0,3600):
>    t=pi*i/360
>    x=t*cos(t)
>    y=t*sin(t)
>    spiralplot.plot(pos=(x,y))
>    sleep(0.001)
>
>
>
>
> Poul Riis

Re: [Visualpython-users] Uniform scaling with gdisplay

[Poul R. <Pou...@sk...>]

Even worse now:

Running the program below now results in the following error message:

Traceback (most recent call last):
  File "C:\pr\python\spiral.py", line 11
    spiralplot =
visualgraph.curve(color=visualgraph.crayola.magenta,display=spiralgraph)
  File "C:\Python32\lib\site-packages\vis\primitives.py", line 82, in
__init__
    if not _other: self.init_defaults(keywords)
  File "C:\Python32\lib\site-packages\vis\primitives.py", line 175, in
init_defaults
    self.material = self.display.material
AttributeError: 'gdisplay' object has no attribute 'material'





import visual.graph as visualgraph
from time import *
from math import *

spiralgraph=visualgraph.gdisplay(title='Spiral', ytitle='x', xtitle='y',
                                 x=0, y=0,
                                 width=800, height=800,
                                 foreground=visualgraph.color.black,
                                 background=visualgraph.color.white)
spiralplot =
visualgraph.curve(color=visualgraph.crayola.magenta,display=spiralgraph)
spiralplot.plot(pos=(-15,-15))
spiralplot.plot(pos=(15,-15))
spiralplot.plot(pos=(15,15))
spiralplot.plot(pos=(-15,15))
spiralplot.plot(pos=(-15,-15))
for i in range(0,3600):
    t=pi*i/360
    x=t*cos(t)
    y=t*sin(t)
    spiralplot.plot(pos=(x,y))
    sleep(0.001)




Poul Riis

Re: [Visualpython-users] Uniform scaling with gdisplay

[Poul R. <Pou...@sk...>]

This iss excellent - thank you!

Best regards,
Poul Riis



Bru...@nc... writes:
>from __future__ import division, print_function
>from visual import *
>scene.title = 'Spiral'
>scene.width = scene.height = 800
>scene.background = color.white
>scene.foreground = color.black
>scale = 1
>xaxis = curve(pos=[(-scale,0),(scale,0)], color=color.gray(.5))
>yaxis = curve(pos=[(0,-scale),(0,scale)], color=color.gray(.5))
>xlabel = label(pos=(0.95*scale,-0.05*scale), text='x', box=0)
>ylabel = label(pos=(0.05*scale,0.95*scale), text='y', box=0)
>
>p = points(color=color.blue)
>kr = 1
>kt = 1
>t = 0
>dt = pi/360
>while True:
>rate(1000)
>r = kr*t
>theta = kt*t
>x = r*cos(theta)
>y = r*sin(theta)
>t += dt
>m = max([x,y])
>if m > scale:
>scale = 1.05*m
>xlabel.pos = (0.95*scale,-0.05*scale)
>ylabel.pos = (0.05*scale,0.95*scale)
>xaxis.pos = [(-scale,0),(scale,0)]
>yaxis.pos = [(0,-scale),(0,scale)]
>p.append(pos=(x,y))

Re: [Visualpython-users] Uniform scaling with gdisplay

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

The easiest way to achieve autoscaling with x and y scales equal is to
not use graphing. Here is the basic idea:

from __future__ import division, print_function
from visual import *
scene.title = 'Spiral'
scene.width = scene.height = 800
scene.background = color.white
scene.foreground = color.black
scale = 1
xaxis = curve(pos=[(-scale,0),(scale,0)], color=color.gray(.5))
yaxis = curve(pos=[(0,-scale),(0,scale)], color=color.gray(.5))
xlabel = label(pos=(0.95*scale,-0.05*scale), text='x', box=0)
ylabel = label(pos=(0.05*scale,0.95*scale), text='y', box=0)

p = points(color=color.blue)
kr = 1
kt = 1
t = 0
dt = pi/360
while True:
    rate(1000)
    r = kr*t
    theta = kt*t
    x = r*cos(theta)
    y = r*sin(theta)
    t += dt
    m = max([x,y])
    if m > scale:
        scale = 1.05*m
        xlabel.pos = (0.95*scale,-0.05*scale)
        ylabel.pos = (0.05*scale,0.95*scale)
        xaxis.pos = [(-scale,0),(scale,0)]
        yaxis.pos = [(0,-scale),(0,scale)]
    p.append(pos=(x,y))

You could also include in the x and y labels the value of "scale".

Bruce Sherwood