#! /usr/bin/env python
"""
lattice.py is a program which generates a 3D image of a simple atomic cubic lattice

This is an example use of the vpython package.

Run the program and rotate the image in 3D.


Paul Eugenio
PHZ4151C
Jan 4, 2019
"""

from __future__ import division, print_function
import vpython as vp


L = 5          # lattice size equals 2*L+1
radius = 0.3   

# generate cubic lattice
for i in range(-L,L+1):
    for j in range(-L,L+1):
        for k in range(-L,L+1):
            vp.sphere(pos=vp.vector(i,j,k),radius=radius)