\ Indicates mouse position relative to center of canvas

const
  unknown=0,north=1,east=2,south=3,west=4;

var current;

procedure direction;
var x,y;
begin
  current:=unknown;
  if cvx>-1 then
    begin
      x:=cvx-250;
      y:=150-cvy;
      if -x<y then
        begin
          if x<y then
            current:=north;
          if x>y then
            current:=east
        end
      else if -x>y then
        begin
          if x>y then
            current:=south;
          if x<y then
            current:=west
        end
    end
end;

begin
  while 1=1 do
    begin
      call wait(10);
      call cvclear;
      call cvline(100,0,400,300);
      call cvline(100,300,400,0);
      call direction;
      if current=unknown then
        call cvball(250,150,20)
      else if current=north then
        call cvball(250,75,20)
      else if current=east then
        call cvball(375,150,20)
      else if current=south then
        call cvball(250,225,20)
      else if current=west then
        call cvball(125,150,20);
      if cvx>-1 then
        begin
          call cvline(cvx,0,cvx,300);
          call cvline(0,cvy,500,cvy);
        end
    end
end.