clear;clc;close all

rectangle('Position',[1,1,1,1],...

'Curvature',[0,0],...

'LineWidth',2,'LineStyle','-')

axis([0.9 2.1 0.9 2.1])

daspect([1,1,1])

x=[1 1 2 2];

y=[1 2 2 1];

n=10000;

axis off

hold on

h=zeros(length(x),1);

for i=1:4

h(i)=plot(x(i),y(i),'r.','markersize',10,'erasemode','none');

end

title('\copyright:qbb')

t=0.001;

dirx=[0,t,0,-t];

diry=[t,0,-t,0];

for i=1:n

x=x+t*dirx*i/10;

y=y+t*diry*i/10;

dirx=diff([x,x(1)]);

diry=diff([y,y(1)]);

if dist([x(1),y(1)],[x(2);y(2)])<15*t

break

end

arrayfun(@set,h,repmat({'xdata'},4,1),num2cell(x'),repmat({'ydata'},4,1),num2cell(y'));

pause(0.01);

end