VPython 3D Objects
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. The objects are listed in alphabetical order.
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.magenta)
Helix
h = helix(pos=vector(0,2,1), axis=vector(5,0,0), radius=0.5, color=(0.96,0.73,0.14))
Label
l = label(pos=vector(0,0.25,0), text='This is a Label', xoffset=20, yoffset=50, space=30, height=16, border=4,font='sans')
Points
p = points(pos=[vector(-1,0,0), vector(1,0,0)], radius=50, color=(1,1,.94))
Pyramid
p = pyramid(pos=vector(5,2,0), size=vector(3,3,2), color=(0.82, 0.41, 0.12))
Ring
r = ring(pos=vector(1,1,1), axis=vector(0,1,0),radius=0.5, thickness=0.1, color=(0.14, 1, 0.83))
Sphere
s = sphere(pos=vector(1,1,1), radius=5, color=(0.5, 1, 0.5))
Text
t = text(text='This is \ntext', #use \n for changing line
align='center', color=(0.94, 0.90, 0.55))
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 it is mostly used to represent spherical objects such as planets or particles such as protons and electrons. Two things must be set; the position (vector), and the radius (numerical value).
Arrow
The arrow is perhaps the most important object for physics simulation. It can be used to represent various forces as well as visualizing vectors. To create an arrow, the position (vector), axis (vector), and the shaftwidth (a numerical value) must be set.
Curve
The curve is often used to create a trail mark that represents a path that the object has moved, and it is also frequently used to create graphs. To create a curve, put the initial position vector of the curve, and append the next positions while updating the position in the while loop.
Application
Following code is an example usage and application of object creation for lab simulations.
## objects ceiling = box(pos=vector(0,0,0), size = vector(0.2, 0.01, 0.2)) # origin is at ceiling ball = sphere(pos=vector(.1,-.2,.3), radius=0.025, color=color.orange) # note: spring initially compressed spring = helix(pos=ceiling.pos, color=color.cyan, thickness=.003, coils=40, radius=0.015) parrow = arrow(color=color.magenta, pos=ball.pos, axis=vector(0,0,0)) farrow = arrow(color=color.red, pos=ball.pos, axis=vector(0,0,0)) trail = curve(color=ball.color) #graphs Kgraph=gcurve(color=color.red) Ugraph=gcurve(color=color.cyan) KUgraph=gcurve(color=color.yellow)
#graph updates are done in the while loop.
See also
Further reading
References
http://www.glowscript.org/docs/VPythonDocs/primitives.html