load (draw);

/* Anzahl der Rechtecke */
  xA : 4;
  yA : 3;
/* Breite der Rechtecke */
  xw : 10;
  yw : 10;

orangespalte : [0];

mesh1 : [];
for i : 0 while i < xA do
  for k : 0 while k < yA do
    block ([],
      p1 : [i*xw,k*yw],
      p2 : [(i+1)*xw,(k+1)*yw],
      if (member (i, orangespalte)) then
        com : [fill_color=red, rectangle(p1,p2)]
      else
        com : [fill_color=white, rectangle(p1,p2)],
      mesh1 : append (mesh1, [com])
    );

mesh2 : [];
for i : 0 while i < xA do
    block ([],
      p1 : [i*xw,0],
      p2 : [(i+1)*xw, yA*yw],
      if (member (i, orangespalte)) then
        com : [fill_color=red, rectangle(p1,p2)]
      else
        com : [fill_color=white, rectangle(p1,p2)],
      mesh2 : append (mesh2, [com])
    );

drawopt : [
        xtics = false,
        ytics = false,
        line_width = 6,
        color = black,
        points_joined = true,
        terminal = png
    ];

draw2d (
  drawopt,
  mesh1,
  file_name = "erweitern11"
);

draw2d (
  drawopt,
  mesh2,
  file_name = "erweitern12"
);