：：：：：在知乎上看到别人用matlab做动画就想学学，正好电机学讲到绕组磁势，那就做一个脉动磁势分解成两个旋转磁势来练练手，同时保存为了avi和gif

clear all;

outputVideo = VideoWriter('1.avi');

outputVideo.FrameRate = 36; %1s36帧，后面是180帧，对应5s视频

open(outputVideo)

figure;

FA=10;

Q=pi/2;

hold on

axis([-(2*FA+2),2*FA+2,-(2*FA+2),2*FA+2]);

axis off;

x1=FA*cos(Q);

y1=FA*sin(Q);

x2=-x1;

y2=y1;

xb=x1+x2;

yb=y1+y2;

line1=annotation('arrow',y_to_norm_v2(0,x1),y_to_norm_v2(0,y1)); %没想到matlab画一个带箭头的线这么困难，最后还是靠大神的y_to_norm_v2解决了问题

line1.Color='red';

line2=annotation('arrow',y_to_norm_v2(0,x2),y_to_norm_v2(0,y2));

line2.Color='green';

line3=annotation('arrow',y_to_norm_v2(0,xb),y_to_norm_v2(0,yb));

line3.Color='blue';

for theta=2*pi/180:2*pi/180:2*pi

%pause(0.2);

x1=10*cos(Q+theta);

y1=10*sin(Q+theta);

x2=-x1;

y2=y1;

xb=x1+x2;

yb=y1+y2;

set(line1,'X',y_to_norm_v2(0,x1),'Y',y_to_norm_v2(0,y1)); %动态改变线的属性，这里就是起始点

set(line2,'X',y_to_norm_v2(0,x2),'Y',y_to_norm_v2(0,y2));

set(line3,'X',y_to_norm_v2(0,xb),'Y',y_to_norm_v2(0,yb));

drawnow; %刷新，相当于以前widows里面刷新窗口repaint

frame = getframe(); %获得画图区作为一帧

im = frame2im(frame);

[A,map] = rgb2ind(im,256);

writeVideo(outputVideo,im);

if theta==2*pi/180

%现已覆盖模式写入指定的gif文件

imwrite(A,map,'1.gif','gif','LoopCount',Inf,'DelayTime',0);

else

%再以追加模式将每一帧写入gif文件

imwrite(A,map,'1.gif','gif','WriteMode','append','DelayTime',0);

end

end

close(outputVideo);

生成的视频：

https://www.zhihu.com/video/1239702725371543552

生成的gif

大神的y_to_norm_v2

Transform Axes units to Normalized Units for Annotation Objects​ww2.mathworks.cn

另外，学习过程中找到的另外一个画箭头线段的函数，不做动画的时候用挺好

arrow​ww2.mathworks.cn