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POLYGON
[GREG2\]POLYGON [(File)Name] [/PLOT] [/VARIABLE] [/FILL [Colour]]
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 X11 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 Name is given as argument, the cursor is not called but the summit
coordinates are read from the corresponding file (X is in column 1, Y in
column 2), or corresponding SIC Variable if the option /VARIABLE is also
present.
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 vertexes), POLY%X and POLY%Y (the corresponding coordinates). The
currently defined POLYGON is used by the commands MEAN and MASK.
If you specify the option /PLOT, the polygon currently loaded will be
plotted. The option /FILL [Colour] will fill the current polygon, with
the current or specified colour.
Gildas manager
2011-09-07