Animate a Square that is sliding along X axis in Matlab-CodePudding

I have a square that is traveling back and forth along the x axis according to a column vector x (at bottom). I would like to animate the motion of the square sliding back and forth along the x-axis. I tried to use patch, hold on, hold off, and Get Frame functions in a for loop, but that did not work. Instead the result is the square getting smeared as in the old squares are not getting removed from the figure. Here is the code:

clf
s = .1;
    figure(1);
    axis equal;
    axis([-1 1  -1 1]);
    
for i = 1:length(x)
    hold on
    X = [x(i,1) - .5*s;
         x(i,1)   .5*s;
         x(i,1)   .5*s;
         x(i,1) - .5*s;];
     Y = [-.5*s;
         -.5*s;
          .5*s;
          .5*s];
    patch(X,Y,'k');
    hold off;
    h = gca;
    F(i) = getframe;
end
movie(F);

Here is the column vector x:

0.250000000000000 0.230782159143542 0.176280043536689 0.0953146856798128 0.000650212865865713 -0.0932030485077490 -0.172186726125664 -0.224543041359108 -0.242303458811820 -0.222203182817347 -0.166192085851484 -0.0817507793230268 0.0186298767049816 0.118170991653033 0.198905540101543 0.246001260876051 0.250959024174034 0.213107724416597 0.138822733533125 0.0407394702062158 -0.0642948796656877 -0.158085053404849 -0.224759025665608 -0.253100286376047 -0.238297378581389 -0.182618266275528 -0.0958896904713370 0.00602839522197084 0.104668511135333 0.183752954307020 0.231574999618735 0.242127812051811 0.214632538642815 0.153856203337548 0.0689710768423088 -0.0273378670448299 -0.120371418450032 -0.195696352800403 -0.241063326708591 -0.249170206446669 -0.218574858836030 -0.154523974516009 -0.0674660734309435 0.0288890782751109 0.119813330828138 0.191877626928792 0.234364270672030 0.240941167981351 0.209893379667572 0.145130717726666 0.0553977698549078 -0.0457864898288502 -0.141584098341353 -0.214945647396668 -0.252189311075765 -0.246607701950267 -0.199000344173733 -0.117539948553725 -0.0163532898953576 0.0870695406469115 0.175127325624604 0.233430214463870 0.252410945754133 0.228805022755430 0.165868916165404 0.0741157391779560 -0.0299825244149044 -0.127575941311610 -0.201938733706939 -0.241944848784945 -0.242264519853537 -0.203786790215477 -0.132560148710489 -0.0395394071796979 0.0608871776036858 0.152636629298216 0.220295640189107 0.252442054488179 0.243446202365058 0.195322881013323 0.116647868987791 0.0209866982124944 -0.0762128632358914 -0.160101037237629 -0.218549398091714 -0.243311095720934 -0.230961374436814 -0.183209095455776 -0.106644747551930 -0.0123109118042467 0.0857290198345198 0.171900620989060 0.231541484378119 0.254192056475618 0.235371165049059 0.178352335891224 0.0928137722294060 -0.00672172862573606 -0.104037530998919 -0.183858736347838

CodePudding user response：

I just ended up going away from patch function because it does not seem to work with hold on hold off commands. I used plot function instead to draw four lines as shown below.

clc
clf
s = .25;
min = -2;
max = 2;
for i = 1:length(x)
    X = [x(i,1)-.5*s, x(i,1) .5*s];
    Y = [-.5*s, -.5*s];
    plot(X,Y,'b');
    axis equal
    axis([min max min max]);
    hold on;
    X = [x(i,1) .5*s, x(i,1) .5*s];
    Y = [-.5*s, .5*s];
    plot(X,Y,'b');
    axis equal
    axis([min max min max]);
    hold on;
    X = [x(i,1) .5*s, x(i,1)-.5*s];
    Y = [.5*s, .5*s];
    plot(X,Y,'b');
    axis equal;
    axis([min max min max]);
    hold on;
    X = [x(i,1)-.5*s, x(i,1)-.5*s];
    Y = [.5*s, -.5*s];
    plot(X,Y,'b');
    axis equal;
    axis([min max min max]);
    hold off
    F(i) = getframe;
end
movie(F)