from __future__ import division
from visual import *
scene.background = color.white
scene.x = scene.y = 0
scene.width=1000
scene.height=600

print """
Ruth Chabay 2002
Single traveling pulse of radiation.
Establishes what we are talking about in derivation
at beginning of chapter 23.
"""

c = 3e8
lamb = 1e-10
h = 1e-10
omega = 2*pi*c/lamb

xx = arange(-2*lamb,-2*lamb+lamb/2, lamb/20.)

xhat = vector(1,0,0)

Evec = []
ff = frame()
z = 0
y = 0
E0 = lamb/2
case = 1
if case is 1:
    ##CASE 1 
    ## E +y, B+z
    for y in arange(-0.8*lamb, 0.8*lamb+lamb/300, 0.8*lamb):
        for x in xx:
            ea = arrow(pos=(x,y,z), axis=(0,E0,0), color=(1.,.6,0),
                       shaftwidth=lamb/40., frame=ff)
            ba = arrow(pos=(x,y,z), axis=(0,0,E0/2), color=(0,1,1),
                       shaftwidth=lamb/40., frame=ff)
            ea.B = ba
            Evec.append(ea)
else:
#### CASE 2
#### E -z, B+y
    for y in arange(-0.8*lamb, 0.8*lamb+lamb/300, 0.8*lamb):
        for x in xx:
            ea = arrow(pos=(x,y,z), axis=(0,0,-E0), color=(1.,.6,0),
                       shaftwidth=lamb/40., frame=ff)
            ba = arrow(pos=(x,y,z), axis=(0,E0/2,0), color=(0,1,1),
                       shaftwidth=lamb/40., frame=ff)
            ea.B = ba
            Evec.append(ea)


scene.mouse.getclick()

dx = vector(lamb/200,0,0)
scene.autoscale=0
while 1:
    rate(50)
    for ea in Evec:
        ea.pos = ea.pos + dx
        ea.B.pos = ea.B.pos + dx