visualpython-users

[Visualpython-users] Improved Windows installer

[Bruce S. <ba...@an...>]

Thanks to a suggestion of David Scherer on how to use an extended version 
of Inno Setup to build the Windows VPython installer, if the installer does 
not find the folder where Python 2.0 is installed it now asks the user to 
choose the installation folder.

And there is now an InstallScripts zip file available on the general 
download page which contains the various scripts I use to create the 
Windows installer and the various zip files (documentation, demos, etc.). 
Included in the zip file is a ReadmeInstall.txt file which explains how the 
scripts are used, and where to find the relevant applications on the web.

Bruce Sherwood

[Visualpython-users] RE: [Edu-sig] In praise of VPython

[Bruce S. <ba...@an...>]

--On Friday, March 02, 2001 12:51 PM -0500 David Scherer 
<dsc...@vy...> wrote:

> p.s. Bruce: Can you say exactly what registry keys are used by the
> installer to locate Python?  Do we prompt for an installation path if the
> correct keys are not found?

Here is the line from the Inno Setup script that creates the VPython 
installer for Windows:

DefaultDirName={reg:HKLM\Software\Python\PythonCore\2.0\InstallPathX,|{sd%7
d\VPython}

Translation: I'm using the registry key 
HKLM\Software\Python\PythonCore\2.0\InstallPathX,, or if this doesn't 
exist, I'm using the system drive:\VPython (typically drive C).

There doesn't seem to be a way in Inno Setup to have conditional 
statements, so I don't see a way to prompt for an installation path in case 
the correct key is not found, nor even to tell the person where the files 
are going. This is why there is a note and FAQ listed with the download. 
(Can't pick this up at the moment because the CIL server is down in 
anticipation of a planned power outage this evening.)

If someone can offer a more flexible installer builder, that would be good. 
But the current installer seems to work well for the unknowledgeble, and 
the knowledgeable should be able to cope.

Bruce

[Visualpython-users] VPython story

[Bruce S. <ba...@an...>]

Another VPython story has shown up on the web:

http://news.linuxprogramming.com/news_story.php3?ltsn=2001-01-26-002-05-CD

Bruce

[Visualpython-users] RE: [Edu-sig] In praise of VPython

[David S. <dsc...@vy...>]

> I have both 2.0 and 2.1a2 on my G: drive.  VPython insists on putting
> all its files on C:, maybe because 2.1 has the last word in some
> registry entry -- probably why I can't get Python 2.0's IDLE to boot,
> even though I can boot the ActivePython Pythonwin interface.

Maybe Tcl/Tk isn't working?

> Once I move all the VPython stuff to G:\Python20, by zipping down and
> unzipping in the correct directory, I still can't get its version
> of IDLE to boot (again, likely for registry reasons -- 2.1 has to
> be my final install).

If the ordinary Python 2.0 IDLE isn't working, it's not too surprising that
the VPython version doesn't work either.  You should try running it from a
command prompt and post the error messages to visualpython-users or
idle-dev.

> A question about VPython -- can I use it independently of its version
> of IDLE?  Like in Pythonwin or the indigenous IDLE?  How about from
> ye old MSDOS box?

It will work fine with command-line Python.  Most existing Python IDEs
except for the VPython IDLE execute the user program in their own process,
which makes VPython programming more difficult (though it remains possible
if you are very careful).  For example, the preferred way to do simple
animations in VPython is something like:

from visual import *
ball = sphere()
while 1:
  rate(100)
  ball.x = ball.x + 0.01

This sort of infinite loop will give some IDEs problems in and of itself.
Worse, visual will attempt to terminate the program forcefully when you
close the graphics window, which will terminate your IDE!  The workaround
is:

from visual import *
scene.exit = 0   # disable automatic exit behavior
ball = sphere()
while scene.visible:
  rate(100)
  ball.x = ball.x + 0.01

which isn't so bad.  But if you screw up you will terminate your IDE and
perhaps lose work.

> Anyway, it looks to me like the Windows registry structure and/or
> Python Windows install process is too awkward to permit Python 2.0
> and Python 2.1 to co-exist peacefully enough for add-ons like VPython
> to work.  So I either blow away the 2.1a2 or sit tight and wait for
> the add-ons to migrate up the development curve.  Or...?  Maybe
> someone out there as both Pythons and VPython all working on the
> same Wintel box?

The add-ons will migrate up the development curve fastest if people with
problems attempt to diagnose them in detail and report them :)

Thanks,

Dave

p.s. Bruce: Can you say exactly what registry keys are used by the installer
to locate Python?  Do we prompt for an installation path if the correct keys
are not found?

RE: [Visualpython-users] why do straight 'curves' have 'knots'?

[David S. <dsc...@vy...>]

Yes, this is a VPython bug.  Thick curves are rendered with rectangular
cross sections, but with shading that makes them look more round than that.
To render these VPython needs to construct a 2D basis for the cross section
of the curve at each point.

  Cross-sectional view of a curve

          ^ Basis vector 2
          |
         /|\
        / | \
       (  x--)--> Basis vector 1
        \   /
         \ /

Some care is taken to make sure that each basis isn't "twisted" with respect
to the previous and next ones, but I wasn't able to get that exactly right.
Straight line segments are particularly bad because finite floating point
precision tends to make them jitter randomly from "concave up" to "concave
down".

You might be able to work around the problem by making the line curve *very*
slightly, e.g pos=(r*cos(theta), r*sin(theta + r/1000.0)) or something.

If anyone can think of a better way to generate the cross sections, of
course, I would love to hear it!

Dave

-----Original Message-----
From: vis...@li...
[mailto:vis...@li...]On Behalf Of Stephen
Highland
Sent: Friday, March 02, 2001 12:14 PM
To: vis...@li...
Subject: [Visualpython-users] why do straight 'curves' have 'knots'?


When I run this simple program, expecting a straight (tilted) line, I get a
thing that's straight, all right, but it has narrow spots in places that
make it look like it's twisted.  What's going on?

from visual import *
theta =0.4
c=curve(radius=0.04,color=color.yellow)
for r in arange(0.1,1.0,0.1):
    c.append(pos=(r*cos(theta),r*sin(theta),0))


The reason I'm building a straight line in segments is so I can color it
differently along its length.

Have I found some sort of VPython error or am I doing something dumb?

---Steve Highland
(still having lots of fun...)

[Visualpython-users] why do straight 'curves' have 'knots'?

[Stephen H. <sh...@ua...>]

When I run this simple program, expecting a straight (tilted) line, I =
get a thing that's straight, all right, but it has narrow spots in =
places that make it look like it's twisted.  What's going on?

from visual import *
theta =3D0.4
c=3Dcurve(radius=3D0.04,color=3Dcolor.yellow)
for r in arange(0.1,1.0,0.1):
    c.append(pos=3D(r*cos(theta),r*sin(theta),0))
  =20
 =20
The reason I'm building a straight line in segments is so I can color it =
differently along its length.

Have I found some sort of VPython error or am I doing something dumb?

---Steve Highland
(still having lots of fun...)

[Visualpython-users] Update

[Bruce S. <ba...@an...>]

Updates for Windows, and the Visual source code, at

	http://cil.andrew.cmu.edu/projects/visual

Ari Heitner modified the frame machinery to let you find the objects in a 
particular frame:

f = frame()
ball = sphere(frame=f)
bar = cylinder(frame=f)
for obj in f.objects:
    obj.color = color.red # make every object in the frame be red

This is in preparation for a larger enhancement Ari is working on, where 
you will be able to say things like "f.color = color.red" or "f.visible = 
0" and make all objects in the frame be red or invisible.

David Andersen compiled the changes for Windows.

[Visualpython-users] re: a wish or two

[<Art...@ao...>]

>>There are basically 3 kinds of code in Visual primitives .. (snip)

That helps.

I had already mentioned to someone that if I were to try to learn
Python extensions I would probably choose to do it via cvisual -
the general subject matter is one I am already famialiar with, and 
I have confidence it represents a clean methodology. And there is
real impetous - cvisual probably already having 90% of the specifics
to implement my interests, but might have to go it a bit on my own 
after that

So I will move in that direction as time allows.

I will try to cry for help only when at the end of a rope.

Looks like some getting some understanding of CXX is a
logical place to start.  We're off.

ART

RE: [Visualpython-users] a wish or two

[David S. <dsc...@vy...>]

> An overview of the cvisual's rendering approach might help me get
> started.

I will help as I can.

> Is there anything available that might help me better understand
> cvisual at
> this level?

There is no technical documentation, sorry :(

> What
> I am seeing in the code, to the extent I follow it, is not what I would
> expect.  If I look
> at the code for a glut sphere or cone I see it being built
> geometrically from
> triangle fans and strips.

There are basically 3 kinds of code in Visual primitives

(1) code to implement the Python interface (attributes + methods).  We use
the CXX library, which wraps C++ classes around Python types and vice-versa,
to make this easier.

(2) code to render the primitive (using triangle strips or other GL
primitives).  This will look a little like the implementations you are used
to, but Visual cannot use OpenGL matrix math (it is too inaccurate when the
scale of the scene is very large or small, which is important for physics).
Therefore the code does transformation and lighting itself using the tmatrix
class.

(3) code to implement mouse picking. This is raytracing code.  The line
between the camera position and the mouse cursor forms a ray which is
intersected with all objects in the scene.  The closest intersection is
taken to be mouse.pick/mouse.pickpos.

> Cvisual seems to look more like ray-tracing code - which I have
> never been able to follow - though wish I could.

Actually, a simple raytracer is a relatively gentle introduction to
graphics, if you find one written for pedagogical value rather than for
efficiency.  Maybe someone needs to write one in Python.

Dave

Re: [Visualpython-users] a wish or two

[<Art...@ao...>]

David wrote -

>Adding a primitive in C++ that would behave similarly but more efficiently
>or triangles would be relatively easy.

>Alpha is harder, because to render translucent surfaces accurately, you need
>to draw them from back to front.  At present, Visual doesn't need to sort
>most primitives (because they are drawn opaquely, and can be zbuffered).  If
>you want to attack this, I can give you some pointers - but it will take
>some effort.

An overview of the cvisual's rendering approach might help me get started. 
What
I am seeing in the code, to the extent I follow it, is not what I would 
expect.  If I look
at the code for a glut sphere or cone I see it being built geometrically from 
triangle fans and strips. 

Cvisual seems to look more like ray-tracing code - which I have never been 
able to
follow - though wish I could.    
 
Is there anything available that might help me better understand cvisual at 
this level?

ART

RE: [Visualpython-users] a wish or two

[David S. <dsc...@vy...>]

> I'm a little desperate for access to triangle primitives to do some stuff
> with
> surfaces. A syntax similar to "curve" would seem ideal.(with the addition
> of the ability to set alpha values).

In principle you can get opaque triangles using convex - a convex shape with
3 vertices is a triangle.  If your surface is the hull of a convex shape,
you can of course use convex directly.

def triangle(v1, v2, v3):
  return convex( pos=[v1,v2,v3] )

Adding a primitive in C++ that would behave similarly but more efficiently
for triangles would be relatively easy.

Alpha is harder, because to render translucent surfaces accurately, you need
to draw them from back to front.  At present, Visual doesn't need to sort
most primitives (because they are drawn opaquely, and can be zbuffered).  If
you want to attack this, I can give you some pointers - but it will take
some effort.

> Haven't done much with c-extensions, so a little dependant here. Tell
> me its not in the cards for the core cvisual, and I guess I'l  give it
> shot to see if I can build in into my own copy.

Speaking only for myself: I won't have time to write a triangle primitive in
the forseeable future.  If you write a good one, however, I wouldn't oppose
integrating it.

Dave

[Visualpython-users] a wish or two

[<Art...@ao...>]

Having some success in getting my hands around cvisual and finding
it quite usable for the rendering of my dynamic geometry toy I have
already done in Python\PyOpenGL.

My plane primitive, in PyOpenGL, took some doing - matrix manipulatin,
etc. In cvisual my plane is drawn as a "curves" primitive in a frame, whose
axis and position is the plane's normal - and I'm done.  Nice.

But....

I'm a little desperate for access to triangle primitives to do some stuff 
with 
surfaces. A syntax similar to "curve" would seem ideal.(with the addition
of the ability to set alpha values). 

Haven't done much with c-extensions, so a little dependant here. Tell
me its not in the cards for the core cvisual, and I guess I'l  give it
shot to see if I can build in into my own copy.

Re: [Visualpython-users] trouble with Mac version of VPython

[Bruce S. <ba...@an...>]

I don't have a problem using Netscape on a Mac to download this. You might 
try a more recent (freeware) Stuffit Expander?

Bruce Sherwood

--On Thursday, February 22, 2001 12:31 PM -0700 "Matthew J. Moelter" 
<mmo...@ca...> wrote:

> I downloaded
> "VPythonMac-2000-12-18.sit.hqx"
> and then tried to open it.
>
> I got the message
> "decoding"  which quickly was replaced by an info box,
> "VPythonMac-2000-12-18.sit.hqx is not a complete
> BinHex file, and therefore can not be"

[Visualpython-users] trouble with Mac version of VPython

[Matthew J. M. <mmo...@ca...>]

I downloaded
"VPythonMac-2000-12-18.sit.hqx"
and then tried to open it.

I got the message
"decoding"  which quickly was replaced by an info box,
"VPythonMac-2000-12-18.sit.hqx is not a complete
BinHex file, and therefore can not be"

I downloaded it from Netscape by clicking and also
by alt-clicking and got the same behavior.

Is it just me or are others having trouble?

Thanks in advance...Matt
--
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
Matthew J. Moelter                    office:  (805) 756-2065
Department of Physics               email:   mmo...@ca...
Calif Polytechnic State Univ          fax:  (805) 756-2435
San Luis Obispo, CA 93407

[Visualpython-users] New graph.py

[Bruce S. <ba...@an...>]

At http://cil.andrew.cmu.edu/projects/visual in the Windows download 
section there is a new Visual zip file (for the visual folder in the Python 
suite), containing a significantly improved graph.py. It handles the 
borders of the screen better. And it fixes a bug that led to a black screen 
on the first plot of a ghistrogram.

A colleague commented today about not knowing about the histogram 
capability of graph.py (from visual.graph import *), so I'll advertise it. 
If you have a list of data, you can in one statement plot a binned sorted 
histogram of that data. For details see the online help, in the graphing 
section.

Bruce Sherwood

[Visualpython-users] Another fix

[Bruce S. <ba...@an...>]

Thanks to Dave Scherer, Ari Heitner, and David Andersen for putting 
together a revised Visual DLL for Windows to fix a bug introduced two days 
ago that made the Visual-to-POVRay convertor not work (had to do with 
"frame=None", so pretty arcane for other programs).

New DLL zip file, new VPython package, and Visual Source zip file, 
available at

	http://cil.andrew.cmu.edu/projects/visual

Bruce Sherwood

[Visualpython-users] credit

[Bruce S. <ba...@an...>]

I should also have specifically thanked David Andersen for rebuilding the 
Windows DLL containing the various bug fixes.

Bruce Sherwood

[Visualpython-users] Update

[Bruce S. <ba...@an...>]

At http://cil.andrew.cmu.edu/projects/visual you can download the Windows 
DLL zip file to get some bug fixes by

David Andersen: curve and convex now honor scene.foreground color

David Scherer: ring now autoscales correctly

Ari Heitner: get error message if you try to place an object in a frame 
that isn't in the object's display window

Thanks, guys!

Bruce Sherwood

P.S. The VPython package for Windows is also up to date, as is the 
VisualSource zip file.

RE: [Visualpython-users] IDLE works, but video demos freeze

[David S. <dsc...@vy...>]

> I just installed VPython on Windows2000. I have this problem, listed
> under FAQ: IDLE works, but video demos freeze. I did what is listed
> under FAQ:

Yes, this is an excellent problem report, thanks.

> I tried to set the hardware acceleration in Display Properties to "none"
> and then the demos work.

As mentioned in the FAQ, this means the problem is almost certainly your GL
drivers.

>   Vendor: S3
>   Version: 1.1 7.30.36
>   Renderer: SavageMX

This is a mobile chipset, so I assume you have a laptop.  (You probably
already know that :)  The safest place to get the latest drivers for a
laptop is the *laptop* manufacturer's web site, since they are generally
compelled to provide support if anything goes wrong.  I suggest that you
look there first.  If you can't find anything there that fixes the problem,
you could try the latest SavageMX drivers from S3's web site
http://s3graphics.com/.  The latest drivers for Win2K appear to be version
7.31.17 (vs. the 7.30.36 you have installed).

> PS: I also went to see the page www.glsetup.com, but I didn't do
> anything with it because there is that warning: "You may experience
> SERIOUS problems with your computer, including being unable to run
> Windows"...

Since working video drivers are needed to run Windows, any source of video
driver upgrades will come with a similar caveat.  However, you may find it
comforting that in my fairly wide personal experience with video driver
problems, I haven't seen a case where the system didn't work well enough to
reinstall the older drivers.

> PS2: I just sent you an email about the shell. Well, I found it. No
> answer is needed concerning this.

Oops.

Dave

RE: [Visualpython-users] IDLE problem after installing VPython

[David S. <dsc...@vy...>]

> I had already installed Python2.0 on Windows2000. Now, I downloaded
> VPython and if I now want to open IDLE (both the Python version and the
> VPython version) an empty window appears and not a shell window as it
> did before.  How can I change this back?

Change the target of the shortcut to IDLE you are using from something like

"c:\Python20\pythonw.exe" "c:\Python20\Tools\idle\idle.pyw"

to

"c:\Python20\pythonw.exe" "c:\Python20\Tools\idle\idle.pyw" -t Python

and you will get a shell window instead of an editor.  Or, after starting
IDLE to the editor window, you can get a shell by choosing "Python Shell"
from the Run menu.

Note that the new IDLE makes it so easy to run a program from the editor
(you don't even have to save it) that in many cases you will find it easier
to add a line at a time to your program and hit F5 to re-execute it after
each change than to use the shell.  In particular, it's much easier to
correct mistakes.

Dave

[Visualpython-users] IDLE works, but video demos freeze

[<Sus...@un...>]

Hi,

I just installed VPython on Windows2000. I have this problem, listed
under FAQ: IDLE works, but video demos freeze. I did what is listed
under FAQ: 
I tried to set the hardware acceleration in Display Properties to "none"
and then the demos work. 
Now, I run glinfo.py and the output is the following: 

Visual-2001-02-09
  c:\python20\visual\__init__.py Thu Feb 08 23:27:40 2001
  c:\python20\visual\graph.py    Tue Jan 16 21:37:36 2001
  c:\python20\dlls\cvisual.dll   Mon Feb 05 09:41:16 2001
  c:\winnt\system32\opengl32.dll Wed Oct 04 05:00:00 2000
OpenGL renderer active.
  Vendor: S3
  Version: 1.1 7.30.36
  Renderer: SavageMX
  Extensions:
                            GL_EXT_abgr
                            GL_EXT_bgra
                GL_EXT_clip_volume_hint
           GL_EXT_compiled_vertex_array
                   GL_EXT_packed_pixels
                    GL_EXT_stencil_wrap
                    GL_EXT_vertex_array
                   GL_KTX_buffer_region
                             GL_S3_s3tc
                     GL_SGI_cull_vertex
             GL_SGI_index_array_formats
                      GL_SGI_index_func
                  GL_SGI_index_material
                   GL_SGI_index_texture
                       GL_WIN_swap_hint


The demos freeze completely if I run them with hardware acceleration,
therefore I cant send you a screenshot. 

Can anyone help me with this? 
thanks 
Susanne

PS: I also went to see the page www.glsetup.com, but I didn't do
anything with it because there is that warning: "You may experience
SERIOUS problems with your computer, including being unable to run
Windows"... 

PS2: I just sent you an email about the shell. Well, I found it. No
answer is needed concerning this. 

[Visualpython-users] IDLE problem after installing VPython

[Susanne M. <sus...@un...>]

Hi,

I had already installed Python2.0 on Windows2000. Now, I downloaded
VPython and if I now want to open IDLE (both the Python version and the
VPython version) an empty window appears and not a shell window as it
did before. 
How can I change this back? 

thanks
Susanne


-- 
-------------------------------------------------------
Susanne Moelbert
Universite de Fribourg
Departement de Physique
CH-1700 Fribourg	
Switzerland		
			

Phone: ++41 (0)26 300 91 46  (office)
       ++41 (0)26 424 19 33  (home)
e-mail: sus...@un...

my homepage: http://ptheosg00.unifr.ch/~moelbert/
-------------------------------------------------------

[Visualpython-users] IDLE replace option fixed

[Bruce S. <ba...@an...>]

Thanks to reports from Mats Wichmann and Doug Cheney, Dave Scherer 
identified a missing component in the VPython version of IDLE that caused 
the "replace" option not to work. A corrected version is now on the VPython 
web site

	http://cil.andrew.cmu.edu/projects/visual

If you have VPython installed, all you need do is download and install the 
IDLE zip file.

Bruce Sherwood

[Visualpython-users] fix for GeForce2

[Bruce S. <ba...@an...>]

In our physics cluster, the lines associated with labels (as in the tick 
marks on a graph) flickered. This was traced to a bug in the GeForce2 video 
driver in use on those Win2000 machines. Dave Scherer found a work-around, 
which David Andersen recompiled into cvisual.dll, and now it works 
properly. Thanks!

There is a new VPython download available for Windows (and a new DLL zip 
file for updating an existing VPython installation).

Bruce Sherwood

Re: [Visualpython-users] Special Request

[Ari H. <ahe...@an...>]

On Fri, Feb 02, 2001 at 05:36:51PM -0500, Jonathan D Anderson wrote:
> I have access to a few SGI machines running IRIX.  My problem is the owner
> of these machines has decided to purchase MAYA instead of a compiler.  I
> was wondering if anyone would create a IRIX build of Python and its
> wonderful Visual counterpart.
> 

Normally we build Visual with gcc on UNIX.

I'm sure pre-compiled binaries of gcc are available someplace like
ftp.metalab.unc.edu (or even perhaps from SGI).

Let me know how it goes, I can probably help with any problems. For IRIX,
you'll have to likely build big chunks of the Python stuff yourself.




ari