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;