Matlab - relleno en 2D y dividir lineas con for

clear all

figure(1)

x=[5 10   10   5    5];

y=[3  3    12   12  3];

    fill(x,y,'w')

    axis([3  13 1 14])

    grid on

clear all

 figure(2)

    x1=5:1:10

    y1=3*ones(1,length(x1))

    x2=x1(end)*ones(1,length(y1))

    y2=linspace(3,12,length(x1))

    x3=x1(end:-1:1)

    y3=y2(end)*ones(1,length(x3))

     x4=x1(1)*ones(1,length(x1))

     y4=y2(end:-1:1)

   x=[x1 x2 x3 x4];

   y=[y1 y2 y3 y4];

    fill(x,y,'w')

    axis([x1(1)-3  x1(end)+3 y2(1)-3  y2(end)+3])

    grid on

function draw_line(p_ini,p_fin)

hold on;

plot([p_ini(1,1) p_fin(1,1)],[p_ini(1,2) p_fin(1,2)])

hold off;

function [pa,pb,pc,pd]=draw_squre(p_ini,p_fin)

pa=p_ini;

pb=[p_fin(1,1) p_ini(1,2)];

pc=p_fin;

pd=[p_ini(1,1) p_fin(1,2)];

draw_line(pa,pb);

draw_line(pb,pc);

draw_line(pc,pd);

draw_line(pd,pa);