VPython 3D Objects

Claimed by Do Won Kim (Fall 2017)

The main purpose of the VPython programming language is to create 3D simulation with creating the 3D objects. To achieve this purpose, VPython already contains a number of built-in 3-dimensional objects, and these objects are displayed in a 3D graphics module called Visual. Familiarizing with these objects is important for lab coding.

List of 3D Objects

VPython is packaged with a variety of 3-Dimensional objects. These objects include:

1. Arrow
2. Box
3. Cone
4. Convex
5. Curve
6. Cylinder
7. Ellipsoid
8. Extrusion
9. Faces
10. Helix
11. Label
12. Points
13. Pyramid
14. Ring
15. Sphere
16. Text

The ease with which these objects can be manipulated using python makes them popular in physics classes.

Important Objects

The following objects appear often in Physics 2.

Sphere

The sphere object can be used to represent a wide variety of things, but perhaps the most important for use in Physics 2 is point charges and protons/electrons. Two things must be set; the position, a vector; and the radius, a numerical value.

Arrow

The arrow is perhaps the most important object for Physics 2. It can be used to represent Electric and magnetic fields as well as visualizing vectors. To create an arrow the position (a vector), axis (a vector), and the shaftwidth (a numerical value) must be set.

Object Uses

Examples of Simple Objects

sphere1 = sphere(pos=vector(4,8,15), radius=16)

arrow1 = arrow(pos=vector(4,8,15), axis=vector(16,23,42)

helix1 = helix(pos=vector(4,8,15), axis=vector(16,23,42) radius=.23)

Modeling Fields

from visual import *

mzofp = 1e-7

oofpez = 9e9

qe = 1.6e-19

proton = sphere(pos=vector(3e-10,0,0), radius=1e-11, color=color.red)

velocity = vector(-5.2e4,0,0) #The proton's velocity

r_obs = vector(0,8e-11,0) #The observation location

deltat = 1e-19 #Timestep

while proton.x < 5e-10:

r = r_obs - proton.pos

rhat = r/mag(r)

Efield = oofpez*qe*rhat/(mag(r)**2)

Bfield = mzofp*qe*cross(velocity,that)/(mag(r)**2)

See also

1. VPython Basics
2. VPython
3. VPython Animation

Further reading

1. 3D object details
2. VPython Information

References

http://www.glowscript.org/docs/VPythonDocs/primitives.html http://vpython.org/contents/docs/shapes.html