Option Explicit

Sub Pathfinder()
  Dim X As Integer, Y As Integer
  Dim nX As Integer, nY As Integer
  Dim ptStart As strcPoint
  Dim ptZiel As strcPoint
  Dim ptPunkt As strcPoint
  Dim bolGefunden As Boolean
  Dim LowValue As Integer

  ptStart.X = -1
  ptZiel.X = -1

  For Y = 0 To MAPHEIGHT
    For X = 0 To MAPWIDTH
      If MAP(X, Y) = TileStart Then
        ptStart.X = X
        ptStart.Y = Y
      End If
      If MAP(X, Y) = TileZiel Then
        ptZiel.X = X
        ptZiel.Y = Y
      End If
      If MAP(X, Y) = TilePunkt Then MAP(X, Y) = TileLeer
    Next X
  Next Y

  If ptStart.X = -1 Then
    lbl_Pfad.Caption = "keinen Startpunkt gefunden !"
    Exit Sub
  End If

  If ptZiel.X = -1 Then
    lbl_Pfad.Caption = "keinen Zielpunkt gefunden !"
    Exit Sub
  End If

  For Y = 0 To MAPHEIGHT
    For X = 0 To MAPWIDTH
      Select Case MAP(X, Y)
        Case TileStart: Path(X, Y) = 0
        Case TileBlock: Path(X, Y) = 999
        Case TileLeer: Path(X, Y) = -1
        Case Else: Path(X, Y) = -1
      End Select
    Next X
  Next Y

  Do
    bolGefunden = False

    For Y = 0 To MAPHEIGHT
      For X = 0 To MAPWIDTH
        MARK(X, Y) = False
        If Path(X, Y) = -1 Then
          For nY = Y - 1 To Y + 1
            For nX = X - 1 To X + 1
              If (nX >= 0 And nY >= 0) And _
                    (nX <= MAPWIDTH And nY <= MAPHEIGHT) And _
                    Not (nX = X And nY = Y) Then
                If Path(nX, nY) >= 0 And Path(nX, nY) <> 999 Then
                  MARK(X, Y) = True
                  bolGefunden = True
                End If
              End If
            Next nX
          Next nY
        End If
      Next X
    Next Y

    For Y = 0 To MAPHEIGHT
      For X = 0 To MAPWIDTH
        If MARK(X, Y) Then
          LowValue = 999
          For nY = Y - 1 To Y + 1
            For nX = X - 1 To X + 1
              If (nX >= 0 And nY >= 0) And _
                    (nX <= MAPWIDTH And nY <= MAPHEIGHT) Then
                If Path(nX, nY) >= 0 Then
                  If Path(nX, nY) < LowValue Then _
                        LowValue = Path(nX, nY)
                End If
              End If
            Next nX
          Next nY
          Path(X, Y) = LowValue + 1
        End If
      Next X
    Next Y
  Loop While bolGefunden

  If Path(ptZiel.X, ptZiel.Y) <> -1 Then
    ptPunkt = ptZiel
    LowValue = Path(ptZiel.X, ptZiel.Y)
    Do While LowValue > 0
      bolGefunden = False
      Do
        Do
          nX = Rnd() * 2 - 1
          nY = Rnd() * 2 - 1
        Loop While ((nX = 0 And nY = 0) Or _
                    (ptPunkt.X + nX) < 0 Or _
                    (ptPunkt.X + nX) > MAPWIDTH Or _
                    (ptPunkt.Y + nY) < 0 Or _
                    (ptPunkt.Y + nY) > MAPHEIGHT)

        If Path(ptPunkt.X + nX, ptPunkt.Y + nY) < LowValue Then
          bolGefunden = True
          MAP(ptPunkt.X, ptPunkt.Y) = TilePunkt
          ptPunkt.X = ptPunkt.X + nX
          ptPunkt.Y = ptPunkt.Y + nY
          LowValue = Path(ptPunkt.X, ptPunkt.Y)
        End If
      Loop While Not bolGefunden
    Loop
    MAP(ptZiel.X, ptZiel.Y) = TileZiel
    lbl_Pfad.Caption = "Pfad gefunden !"
  Else
    lbl_Pfad.Caption = "Keinen Pfad gefunden !"
  End If
End Sub