PPMSHEAR

NAME

      ppmshear - shear a portable pixmap by some angle

SYNOPSIS

      ppmshear angle [ppmfile]

DESCRIPTION

      Reads a portable pixmap as input.  Shears it by the specified angle
      and produces a portable pixmap as output.  The angle is in degrees
      (floating point), and measures this:
          +-------+  +-------+
          |       |  |\       \
          |  OLD  |  | \  NEW  \
          |       |  |an\       \
          +-------+  |gle+-------+
      If the angle is negative, it shears the other way:
          +-------+  |-an+-------+
          |       |  |gl/       /
          |  OLD  |  |e/  NEW  /
          |       |  |/       /
          +-------+  +-------+
      The angle should not get too close to 90 or -90, or the resulting
      pixmap will be unreasonably wide.
      The shearing is implemented by looping over the source pixels and
      distributing fractions to each of the destination pixels.

SEE ALSO

      pnmflip(1), ppm(5)

AUTHOR

      Copyright (C) 1989 by Jef Poskanzer.
      Permission to use, copy, modify, and distribute this software and its
      documentation for any purpose and without fee is hereby granted,
      provided that the above copyright notice appear in all copies and that
      both that copyright notice and this permission notice appear in
      supporting documentation.  This software is provided "as is" without
      express or implied warranty.