function DrawHexGrid(HexSize);
size = HexSize;
var hex_length = 1.5 * size;
var hex_height = size * (sqrt 3);
var y = size * (height_of_grid/-2);
for (var count1 = 1; count1 < height_of_grid; count1++)
{
  var x = size * (length_of_grid/-2);
  for (var count2 = 1; count2 < length_of_grid+1; count2++)
  {
    for (var Φ = -30; Φ != 330; Φ+=60)
    {
      go to x: x + (size * sin (Φ)) y: y + (size * cos (Φ)) - (hex_height * (count1-1 mod 2));
      pen down;
    }
    pen up;
    x = x + hex_length;
  }
y = y + hex_height;
}