include c:\cxpl\codes;          \intrinsic 'code' declarations
int X, Y, Dir;
[SetVid($13);                   \set 320x200 graphic video mode
X:= 50;  Y:= 50;  Dir:= 0;      \start in middle facing east
repeat  if ReadPix(X,Y) then    \(black and white are reversed)
                [Dir:= Dir-1;\left\   Point(X,Y, 0\black\)]
        else    [Dir:= Dir+1;\right\  Point(X,Y,$F\white\)];
        case Dir & 3 of
          0:    X:= X+1;        \east
          1:    Y:= Y+1;        \south
          2:    X:= X-1;        \west
          3:    Y:= Y-1         \north
        other   [];
until   X<0 ! X>=100 ! Y<0 ! Y>=100;
X:= ChIn(1);                    \wait for keystroke
SetVid(3);                      \restore normal text mode
]