function drawboard
  a = [10 100 50];
  b = [20 50 100];
  c = [0.5 0.5 0.5];
  patch(a, b, c,'FaceColor','red');
  
x = [10 100 100];
  y = [10 100 50];
  z = [0 0 0];
  blpatch = patch(x,y,z,'FaceColor','black');
  pause(1);
  delete(blpatch);

end