program Graph3_Example (input,output);

uses crt,graph3;

const
     BG=0;

var
     len,
     colr:integer;

(**************************************************************************)

procedure Go_Origin (len:integer);

     begin  {procedure Go_Origin}
          penup;
          back (len);
     end;   {procedure Go_Origin}

(**************************************************************************)

procedure Draw_Ln (len,colr:integer);

     begin  {procedure Draw_Ln}
          pendown;
          turnleft (3);
          setpencolor (colr);
          forwd (len);
          Go_Origin (len);
     end;   {procedure Draw_Ln}

(**************************************************************************)
(* Main program                                                           *)

begin  {main program}
     clrscr;
     graphcolormode;
     randomize;
     graphbackground (BG);
     palette (2);
     len:=0;
     colr:=1;
     repeat
          Inc (len);
          Draw_Ln (len,colr);
          delay (1);
          if len > 100 then
               begin  {if statement}
                    len:=0;
                    colr:=random (4);
               end;   {if statement}
     until keypressed;
end.   {main program}