VPython
Claimed by Nathan Cheek
VPython is a Python graphics module used for modeling objects in 3-dimensional space. In the field of physics, this is especially useful for calculating and modeling complex relationships between objects and their properties.
Installation
VPython is compatible with Windows, OSX, and Linux. While there is an older VPython version available that supports Python 3, the Georgia Tech physics courses use Python 2 syntax so it is recommended to install the latest version of VPython as outlined below.
Windows
1. Install Python-2.7.
2. Download and install VPython from Sourceforge.
To troubleshoot any installation issues, look at the extensive VPython Windows installation guide.
OSX
1. Install Python-2.7. This is required as the version of Python that Apple provides is not compatible.
2. Download and install the VPython package from Sourceforge.
To troubleshoot installation issues, see the extensive VPython Mac installation guide.
GNU/Linux
Some Linux distributions include VPython in their repositories. For example, to install VPython in Ubuntu 15.04:
sudo apt-get install python-visual
If your Linux distribution's repository does not have the latest version of VPython, you can run the Windows version using Wine. The VPython Linux installation guide contains detailed instructions.
Getting started with VPython
The easiest way to use VPython is with VIDLE. VIDLE is a development environment and is the most useful for editing and running code. To start, open the VIDLE application (it may be called something like VIDLE-Py2.7). A blank file should open. Type the following two lines in:
from __future__ import division
from visual import *
This first line tells Python to not use integer division, which would result in 1/3 returning the floor 0 instead of 0.3333333333333333. The second line tells Python to import everything from the visual (VPython) library for you to use.
After these two lines, you can create objects, assign variables, do calculations, and much more. You can also run VPython from the command line, although it may require additional setup.
Creating VPython Objects
When you create objects, it is often useful to assign them to variables so you can reference them later to either get or set values describing for example the position and size of the object.
Sphere
particle = sphere(pos=(0,0,0), radius=8, color=color.blue)
This creates a blue sphere at the origin <0,0,0> with radius 8.
Arrow
arrowToOrigin = arrow(pos=(5,0,0), axis=(-5,0,0), color=color.green)
This creates a green arrow pointing from <5,0,0> to the origin <0,0,0>.
Cylinder
wire = cylinder(pos=(0,0,0), axis=(100,0,0), radius=1, color=color.yellow)
This creates a yellow cylinder starting at the origin <0,0,0> and extending to <100,0,0> with radius 1.
Updating objects
If you assign an object to a variable (such as particle or arrowToOrigin above) you can adjust its parameters such as its location. For the above sphere, you can change its location to <1,2,3> with:
particle.pos=(1,2,3)
To change the axis of the above arrow to point to <5,0,10>, use:
arrowToOrigin.axis=(0,0,10)
Useful built-in functions
VPython includes various functions that can make your calculations much easier. The following functions simplify mathematical operations on vectors and will come in handy very often.
Cross-multiply two vectors
cross(vectorA, vectorB)
Magnitude of a vector
mag(vector)
Unit vector of a vector
norm(vector)
Connectedness
- How is this topic connected to something that you are interested in?
I am very interested in programming. I have used Python for years, so translating Physics problems into VPython code is a great way to cement the fundamental ideas in my mind.
- How is it connected to your major?
VPython helps to bridge the worlds of Computer Science and Physics.
- Is there an interesting industrial application?
History
VPython was originally released in 2000 by David Scherer after he took an introductory physics class at Carnegie Mellon University. At the time, the school used the cT programming language for 2D modeling, and David saw the need for something better. Working with several people including professors Ruth Chabay and Bruce Sherwood, he developed a Python module called Visual. Visual Python or VPython featured 3D modeling, as well as an easier-to-understand object-oriented syntax. Beginning in 2002, the National Science Foundation had awarded $292,286.00 as of December 2015 for the further development of this tool. VPython is released under an Open Source license, and development continues today.
See also
If you have never used Python, the VPython Basics wiki page has information for getting started with Python programming.
Further reading
Books, Articles or other print media on this topic
External links
You Should Be Coding in Your Physics Course
References
This section contains the the references you used while writing this page