DEFINE Konturverfolgung
  LOCAL P0
  LOCAL P1
  LOCAL Pend
  LOCAL P
  LOCAL Pa
  LOCAL Pe
  LOCAL Px
  LOCAL Py
  LOCAL V0
  LOCAL Suchradius
  LOCAL Fangradius
  LOCAL Suchwinkel
  LOCAL Suchzahl
  LOCAL Zaehler
  LOCAL Schleifenzahl
  LOCAL Pruefer
  LOCAL Test
  LET Suchradius 0.01
  LET Fangradius 0.0085
  LET Suchwinkel 60
  LET Suchzahl ((360/Suchwinkel) - 1)
  LET Pruefer 0
  LET Schleifenzahl 0
  OPEN_OUTFILE 1 DEL_OLD 'TMP'
  CATCH VERTEX
  READ PNT 'Startpunkt antippen' P0
  LET Pend P0
  CATCH ELEM
  READ PNT 'Element antippen' P1
  INQ_ELEM P1
  LET Pa (INQ 101)
  LET Pe (INQ 102)
  LET V0 ((P1 - P0)/(LEN (P1 - P0)))
  IF (Pa=P0)
    LET P1 Pe
    LET Test 0
  ELSE
    LET P1 Pa
    LET Test 1
  END_IF
  LET Px P0
  LET Py P1
  WRITE_FILE 1 Px
  LOOP
    LET Zaehler 0
    REPEAT
      LET Zaehler (Zaehler+1)
      LET V0 (ROT V0 (- Suchwinkel))
      LET P (P1 - (V0*Suchradius))
      CATCH NO_VIEWPORT_RANGE Fangradius
      INQ_ELEM P
      IF (INQ 403=LINE)
        LET Pa (INQ 101)
        LET Pe (INQ 102)
        IF (Pa=P1)
          LET P1 Pe
          LET P0 Pa
        ELSE
          LET P1 Pa
          LET P0 Pe
        END_IF
        WRITE_FILE 1 P0
        LET V0 ((P1 - P0)/(LEN (P1 - P0)))
      END_IF
      IF (Zaehler>Suchzahl)
        LET Pruefer 1
      END_IF
    UNTIL ((INQ 403=LINE) OR (Zaehler>Suchzahl))
  EXIT_IF ((P1=Pend) OR (Pruefer=1))
    LET Schleifenzahl (Schleifenzahl+1)
  END_LOOP
  CATCH NO_VIEWPORT_RANGE 0
  CLOSE_FILE 1
  EDIT_FILE 'TMP'
END_DEFINE