POLYGON
Keywords: greg

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POLYGON

            [GREG2\]POLYGON  [(File)Name]  [/PLOT]  [/VARIABLE] [/FILL [Colour]]
        [/HATCH [Ipen] [Angle] [Separ] [Phase]]

        If no argument and no option, it calls the interactive cursor to  define
        the polygon summits. Type any key to go to next summit, C to correct the
        last one, D to delete it, and type E to end the polygon definition.  The
        last polygon side will then appear. The polygon definition may be abort-
        ed by typing Q. For graphical displays, you may use  the  mouse  buttons
        for the commands. The left mouse button draws a vertex, the middle mouse
        button deletes the last vertex, and the  right  mouse  button  ends  the
        polygon  definition.  After  the  use of the cursor, the polygon plot is
        stored in the GTV metacode in a segment named POLYGON. You can delete it
        with the command CLEAR SEGMENT.

        If a (File)Name is given as argument, the cursor is not called. The sum-
        mit coordinates are read from:
          - the named ASCII file (X in column 1, Y in column 2) if no option  is
            present,
          - the  named SIC variable, if /VARIABLE is present. It can be an array
            of the form:
                   VAR[NXY,2]  Real or Double
            or a structure of the form (i.e. same as output):
                   VAR%NXY         Integer or Long
                   VAR%X[VAR%NXY]  Real or Double
                   VAR%Y[VAR%NXY]  Real or Double

        Whereever they come from (cursor, file, or variable), the polygon values
        are   stored   internally;   they   can  be  printed  with  the  command
        GREG2\WRITE POLYGON, and they correspond to the variables POLY%NXY (num-
        ber of vertices), POLY%X and POLY%Y (the corresponding coordinates). The
        currently defined POLYGON is used by the commands MEAN and MASK.

        The polygon loaded by the command can directly be plotted with the  fol-
        lowing options:
          /FILL  [Colour]:  the  polygon  is  color-filled  with the current pen
              colour or with the specified colour (see HELP PEN /COL for  possi-
              bilities),
          /HATCH [Ipen] [Angle] [Separ] [Phase]: the polygon is filled with par-
              allel hatch lines with the specified pen (default  current),  with
              the  given  angle  in degrees (default 45), separation in physical
              units (default 0.25 cm), and phase from 0 to  1  to  displace  the
              lines  by  this  fraction of the separation from a fixed reference
              (default 0).
          /PLOT: the polygon contours are drawn with the current pen,
        For a color-filled and/or hatched and/or contoured polygon, these  three
        options can be combined; they will be executed in the above order.