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| Keywords: Transmission line animation3.gif en A wave traveling rightward along a lossless transmission line Black dots represent electrons and arrows show the electric field 2014-11-09 19 37 14 own Sbyrnes321 other versions cc-zero Source code <source lang python > C Steven Byrnes 2014-2016 This code is released under the MIT license http //opensource org/licenses/MIT This code runs 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 import pygame as pg from numpy import cos pi sin linspace import subprocess os directory_now os path dirname os path realpath __file__ frames_in_anim 100 animation_loop_seconds 5 time in seconds for animation to loop one cycle bgcolor 255 255 255 background is white ecolor 0 0 0 electrons are black wire_color 200 200 200 wire color is light gray arrow_color 140 0 0 pygame draws pixel-art not smoothed Therefore I am drawing it bigger then smoothly shrinking it down img_height 180 img_width 900 final_height 60 final_width 300 ~23 megapixel limit for wikipedia animated gifs assert final_height final_width frames_in_anim < 22e6 transmission line thickness and y-coordinate of the top of each wire tl_thickness 27 tl_top_y 40 tl_bot_y img_height - tl_top_y - tl_thickness + 2 wavelength 1 1 img_width e_radius 4 dimensions of triangular arrow head this is for the longest arrows; it's scaled down when the arrow is too small arrowhead_base 9 arrowhead_height 15 width of the arrow line arrow_width 6 number of electrons spread out over the transmission line top plus bottom num_electrons 100 max_e_displacement is defined here as a multiple of the total electron path length roughly twice the width of the image because we're adding top + bottom max_e_displacement 1/60 num_arrows 20 max_arrow_halflength 22 def tup_round tup round each element of a tuple to nearest integer return tuple int round x for x in tup def draw_arrow surf x tail_y head_y draw a vertical arrow Coordinates do not need to be integers calculate dimensions of the triangle; it's scaled down for short arrows if abs head_y - tail_y > 1 5 arrowhead_height h arrowhead_height b arrowhead_base else h abs head_y - tail_y / 1 5 b arrowhead_base h / arrowhead_height if tail_y < head_y downward arrow triangle tup_round x head_y tup_round x - b head_y - h tup_round x + b head_y - h triangle_middle_y head_y - h/2 else upward arrow triangle tup_round x head_y tup_round x - b head_y + h tup_round x + b head_y + h triangle_middle_y head_y + h/2 pg draw line surf arrow_color tup_round x tail_y tup_round x triangle_middle_y arrow_width pg draw polygon surf arrow_color triangle 0 def e_path param phase_top_left as param goes 0 to 1 this returns 'pos' x y 'phase' phi where x y is the coordinates of the corresponding point on the electron dot path and phi is the phase for an electron at that point on the path phase_top_left is phase of the left side of the top wire d is a vertical offset between the electrons and the wires d tl_thickness - e_radius - 2 pad is how far to extend the transmission line beyond the image borders since those electrons may enter the image a bit pad 36 path_length 2 img_width + 2 pad howfar param path_length move right across top transmission line if howfar < path_length / 2 x howfar - pad y tl_top_y + d phase phase_top_left + 2 pi x / wavelength return 'pos' x y 'phase' phase then move left across the bottom transmission line x path_length - howfar - pad y tl_bot_y + tl_thickness - d phase phase_top_left + 2 pi x / wavelength return 'pos' x y 'phase' phase def main 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 for frame in range frames_in_anim phase_top_left -2 pi frame / frames_in_anim initialize surface surf pg Surface img_width img_height surf fill bgcolor ; draw transmission line pg draw rect surf wire_color 0 tl_top_y img_width tl_thickness pg draw rect surf wire_color 0 tl_bot_y img_width tl_thickness draw electrons Remember param is an abstract coordinate that goes from 0 to 1 as the electron position goes right across the top wire then left across the bottom wire equilibrium_params linspace 0 1 num num_electrons phases e_path a phase_top_left 'phase' for a in equilibrium_params now_params equilibrium_paramsi + sin phasesi max_e_displacement for i in range num_electrons coords e_path a phase_top_left 'pos' for a in now_params for coord in coords pg draw circle surf ecolor tup_round coord e_radius draw arrows arrow_params linspace 0 0 5 num num_arrows for i in range len arrow_params a arrow_paramsi arrow_x e_path a phase_top_left 'pos'0 arrow_phase e_path a phase_top_left 'phase' head_y img_height/2 + max_arrow_halflength cos arrow_phase tail_y img_height/2 - max_arrow_halflength cos arrow_phase draw_arrow surf arrow_x tail_y head_y shrink the surface to its final size and save it 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 Use the convert command part of ImageMagick to build the animation command_list 'convert' '-delay' frame_delay '-loop' '0' + filename_list + 'anim gif' 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 main </source> Transmission lines Animations of electronics Impedance Animations of vibrations and waves Images with Python source code Animated GIF files | ||||
