input colorbrewer-rgb
picture orthogonals;
orthogonals = image(
 interim ahangle := 30;
 z0 = 42 left  rotated normaldeviate;
 z1 = 30 up    rotated normaldeviate;
 z2 = 31 right rotated normaldeviate;
 z3 = 34 down  rotated normaldeviate;
 path s[];
 for i=0 upto 3:
   s[i] = unitsquare zscaled (z[(i+1) mod 4] - z[i]) shifted z[i];
   z[i+4] = 1/2[point 0 of s[i], point 2 of s[i]];
 endfor
 z8 = whatever[z4, z6] = whatever[z5, z7];

 for i=0 upto 3:
   fill s[i] withcolor if odd i: Blues else: Oranges fi 8 1;
   draw point 3 of s[i] -- subpath (1,4) of s[i] -- point 2 of s[i] withcolor 3/4;
   drawarrow subpath (0, 1) of s[i];
 endfor
 draw unitsquare scaled 5 rotated angle (z4-z6) shifted z8 withcolor 3/4;
 drawarrow z4--z6;
 drawarrow z5--z7;
);

vardef with_rounded_corners expr p =
 for i=1 upto length p:
   subpath (i-15/16, i-1/16) of p ..
 endfor cycle
enddef;