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MGH_POLYFILLA

MGH_POLYFILLA

Name


  MGH_POLYFILLA

Description


    Given a 2-D polygon and a rectangular grid, this function returns
    an array indicating which of the pixels in the grid is inside the
    polygon.
   
    See also MGH_POLYFILLG.

Calling Sequence


    result = mgh_polyfilla(x, y, sx, sy[, FRACTION=fraction][, PACK=1|0])

Positional Parameters


  x,y (input, numeric vectors)
    Vectors defining the polygon in the "subscript space" of the
    grid.
    sx,sy (input, integer scalars)
      Dimensions of the pixel grid on which the polygon is
      superposed.

Keyword Parameters


    FRACTION (output, floating array)
      For each pixel index, return the fractional area of that
      pixel contained inside the polygon, between 0 and 1. This
      parameter has the same shape as the return values
    COUNT (output, sclar integer)
      The number of pixels inside the polygon.
    PACK (input, switch)
      Determines the form in which the results are returned. If PACK
      is 0, the return value is a byte array of dimensions [sx,sy]
      specifying whether each pixel is inside the polygon. If PACK is
      1 (default), the return value is an integer array containing
      the 1-D indices of all pixels

Return Value


    The function determines which pixels are (at least partially)
    inside the polygon. The form of the return value depends on the
    setting of the PACK switch.
###########################################################################
  Copyright (c) 2001-2015 NIWA:
  http://www.niwa.co.nz/
  Licensed under the MIT open source license:
  http://www.opensource.org/licenses/mit-license.php
###########################################################################

Modification History


    Mark Hadfield, 2001-10:
      Written, based on JD Smith's POLYFILLAA function.
    Mark Hadfield, 2015-02:
      Source code format updated.



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