File:Electron asymmetric motion animation.gif
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外观
Electron_asymmetric_motion_animation.gif (300 × 150像素,文件大小:131 KB,MIME类型:image/gif、循环、60帧、1.8秒)
摘要
描述Electron asymmetric motion animation.gif |
English: An electron (purple) is being pushed side-to-side by a sinusoidally-oscillating force. But because the electron is in an anharmonic potential (black curve), the electron motion is not sinusoidal. The three arrows show the Fourier series of the motion: The blue arrow corresponds to ordinary (linear) susceptibility, the green arrow corresponds to second-harmonic generation, and the red arrow corresponds to optical rectification. |
日期 | |
来源 | 自己的作品 |
作者 | Sbyrnes321 |
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本作品采用知识共享CC0 1.0 通用公有领域贡献许可协议授权。 |
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http://creativecommons.org/publicdomain/zero/1.0/deed.enCC0Creative Commons Zero, Public Domain Dedicationfalsefalse |
Source code
"""
(C) Steven Byrnes, 2014. This code is released under the MIT license
http://opensource.org/licenses/MIT
This code should work in Python 2.7 or 3.3. It requires imagemagick to be
installed; that's how it assembles images into animated GIFs.
"""
from __future__ import division, print_function
import pygame as pg
from math import pi
from cmath import exp
import subprocess, os
directory_now = os.path.dirname(os.path.realpath(__file__))
frames_in_anim = 60
animation_loop_seconds = 2 #time in seconds for animation to loop one cycle
bgcolor = (255,255,255) #white
potential_curve_color = (0,0,0) #black
ecolor = (100,0,100) #electron is purple
linear_color = (0, 0, 150)
shg_color = (0, 150, 0)
const_color = (150, 0, 0)
eradius = 20
img_height = 500
img_width = 1000
top_arrow_y = 350
middle_arrow_y = 380
bottom_arrow_y = 410
arrow_width = 8
# Limits of the potential curve
xmin = 100
xmax = 900
ymin = 40
ymax = 300
# pygame draws pixel-art, not smoothed. Therefore I am drawing it
# bigger, then smoothly shrinking it down
final_width = int(round(0.3 * img_width))
final_height = int(round(0.3 * img_height))
def potential_curve(x):
"""
My potential curve y as a function of x
"""
xscaled = (x-xmin) / (xmax - xmin)
if xscaled < 0.2:
yscaled = (0.2 - xscaled)**2 / (0.2**2)
else:
yscaled = (xscaled - 0.2)**2 / (0.8**2)
# flip it, because higher y-coordinate is lower in pygame drawing
yscaled = 1 - yscaled
return ymin + (ymax - ymin) * yscaled
curve_bottom_x = 0.79 * xmin + 0.21 * xmax
curve_bottom_y = potential_curve(curve_bottom_x)
def electron_curve(x):
"""
The path that the electron center travels along
"""
# xscaled = (x-xmin) / (xmax - xmin)
y = min(potential_curve(x), potential_curve(x+eradius), potential_curve(x-eradius))
return y - eradius
# Constants and function for calculating electron motion
linear_coef = 0.3
shg_coef = 0.07
displacement = 0.32
def e_x(phase):
"""
x-position of electron as a function of phase (from 0 to 2pi)
"""
xscaled = (linear_coef * exp(1j * phase) + shg_coef * exp(2j * phase)
+ displacement).real
return xmin + xscaled * (xmax - xmin)
def draw_arrow(surf, tail_xy, head_xy, width=2, color=(0,0,0)):
"""
draw a horizontal arrow
"""
# tail_xy and head_xy are 2-tuples. Unpack them first
tail_x, tail_y = tail_xy
head_x, head_y = head_xy
assert head_y == tail_y
h = 16 # arrowhead height
b = 18 # arrowhead half-base
if tail_x < head_x:
# rightward arrow
triangle = [(head_x, head_y),
(head_x - h, head_y - b),
(head_x - h, head_y + b)]
else:
# leftward arrow
triangle = [(head_x, head_y),
(head_x + h, head_y - b),
(head_x + h, head_y + b)]
pg.draw.line(surf, color, (tail_x, tail_y), (head_x, head_y), width)
pg.draw.polygon(surf, color, triangle, 0)
def main():
""" function for creating the animated GIF """
# Make and save a drawing for each frame
filename_list = [os.path.join(directory_now, 'temp' + str(n) + '.png')
for n in range(frames_in_anim)]
# Put the potential curve in the form of a list of points, to be drawn below
xs = range(xmin, xmax + 1,1)
ys = [potential_curve(x) for x in xs]
potential_curve_path = zip(xs, ys)
for frame in range(frames_in_anim):
phase = 2 * pi * frame / frames_in_anim
electron_x = e_x(phase)
electron_y = electron_curve(electron_x)
# initialize surface
surf = pg.Surface((img_width,img_height))
surf.fill(bgcolor)
# draw potential curve
pg.draw.lines(surf, potential_curve_color, False,
potential_curve_path, 10)
# draw vertical line to first arrow
pg.draw.line(surf, (0,0,0), (curve_bottom_x,curve_bottom_y),
(curve_bottom_x, top_arrow_y), 3)
# draw three arrows
linear_term = (linear_coef * exp(1j * phase)).real * (xmax - xmin)
shg_term = (shg_coef * exp(2j * phase)).real * (xmax - xmin)
draw_arrow(surf,
(curve_bottom_x, top_arrow_y),
(curve_bottom_x + linear_term, top_arrow_y),
width=arrow_width, color=linear_color)
draw_arrow(surf,
(curve_bottom_x + linear_term, middle_arrow_y),
(curve_bottom_x + linear_term + shg_term, middle_arrow_y),
width=arrow_width, color=shg_color)
draw_arrow(surf,
(curve_bottom_x + linear_term + shg_term, bottom_arrow_y),
(electron_x, bottom_arrow_y),
width=arrow_width, color=const_color)
# draw electron
pg.draw.circle(surf, ecolor,
((int(round(electron_x)), int(round(electron_y)))),
eradius, 0)
shrunk_surface = pg.transform.smoothscale(surf, (final_width, final_height))
pg.image.save(shrunk_surface, filename_list[frame])
seconds_per_frame = animation_loop_seconds / frames_in_anim
frame_delay = str(int(seconds_per_frame * 100))
command_list = ['convert', '-delay', frame_delay, '-loop', '0'] + filename_list + ['anim.gif']
# Use the "convert" command (part of ImageMagick) to build the animation
subprocess.call(command_list, cwd=directory_now)
# Earlier, we saved an image file for each frame of the animation. Now
# that the animation is assembled, we can (optionally) delete those files
if True:
for filename in filename_list:
os.remove(filename)
return
main()
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受版权保护,并由版权所有者释出于公有领域 简体中文(已转写)
4 3 2014
image/gif
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当前 | 2014年3月5日 (三) 03:49 | ![]() | 300 × 150(131 KB) | Sbyrnes321 | got rid of a vertical line |
2014年3月5日 (三) 03:31 | ![]() | 300 × 150(132 KB) | Sbyrnes321 | User created page with UploadWizard |
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