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| Keywords: Electron asymmetric motion animation.gif en 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 2014-03-04 22 26 10 own Sbyrnes321 cc-zero Source code <source lang python > 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_listframe 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 </source> Uploaded with UploadWizard Animations of physics Nonlinear optics Fourier series Images with Python source code Animations of vibrations and waves | ||||
