clc
a=[0, 0];
b=[-100 ,100];
c=[-100,100];
d=[0 ,0];
figure(1)
plot(a,b,'k','LineWidth',10)
hold on
plot(c,d,'k','LineWidth',10)
hold on
x1=[-100,0];
x2=[0 -80];
v=1;
aa=[];
ba=[];
for i=1:180;
aa(i)=-100+v.*i;
drawnow;
h1=plot(aa(i),0,'-or','LineWidth',5);
pause(0.01) ;
bb(i)=-80+v.*i;
drawnow;
h2=plot(0,bb(i),'-ob','LineWidth',5);
pause(0.01) ;
delete(h1);
delete(h2);
end