VPython 3D Objects

Claimed by Do Won Kim (Fall 2017) (In Progress)

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.

Before start coding, make sure to have

from __future__ import division
from visual import *

on the top of your script.

This document is written based on VPython 7.

List of 3D Objects

Image of Each Objects

VPython is packaged with a variety of 3-Dimensional objects. By clicking each names of the objects, you can go to the official description of each objects from Glowscript.

Arrow

Error creating thumbnail: sh: /usr/bin/convert: No such file or directory Error code: 127

The example arrow

Box

Error creating thumbnail: sh: /usr/bin/convert: No such file or directory Error code: 127

The example box

Cone

Curve

Cylinder

Ellipsoid

Extrusion

Helix

Label

Points

Pyramid

Ring

Sphere

Text

Example Code of Each Objects

Arrow

a = arrow(pos=(0,2,1),axis=(5,0,0), color = color.red)

Box

b = box(pos=(0,0,0),length=3, height=3, width=3, color = color.orange)

Cone

c = cone(pos=(0,0,0),axis=vector(2,0,0), radius=1, color = color.yellow)

Curve

c = curve(pos=[(-1,-1,0), (1,-1,0)], color = color.green) #create object
c.append(pos=(3,2,-2)) #append next position vector
c.append(pos=(4,1,2))

Cylinder

c = cylinder(pos=vector(0,2,1), axis=vector(5,0,0), radius=1, color=color.cyan)

Ellipsoid

e = ellipsoid(pos=vector(0,0,0), length=3, height=5, width=7, color=color.blue)

Extrusion

#define polygons first
tri = Polygon( [(-2,0), (0,4), (2,0)] )
circ = shapes.circle(pos=(0,1.5), radius=0.8)
straight = [(0,0,0),(0,0,-4)]
#create extrusion
e = extrusion(pos=straight, shape=tri-circ, color=color.yellow)

Helix

Label

Lights

Points

Pyramid

Ring

Sphere

Text

Commonly Used Objects

The following objects are often used in class lab.

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