NAME
    CAD::Drawing::Calculate - Calculations for CAD::Drawing

DESCRIPTION
    This module provides calculation functions for the CAD::Drawing family
    of modules.

AUTHOR
      Eric L. Wilhelm
      ewilhelm at sbcglobal dot net
      http://pages.sbcglobal.net/mycroft

COPYRIGHT
    This module is copyright (C) 2003 by Eric L. Wilhelm and A. Zahner Co.

LICENSE
    This module is distributed under the same terms as Perl. See the Perl
    source package for details.

    You may use this software under one of the following licenses:

      (1) GNU General Public License
        (found at http://www.gnu.org/copyleft/gpl.html)
      (2) Artistic License
        (found at http://www.perl.com/pub/language/misc/Artistic.html)

NO WARRANTY
    This software is distributed with ABSOLUTELY NO WARRANTY. The author and
    his employer will in no way be held liable for any loss or damages
    resulting from its use.

Modifications
    The source code of this module is made freely available and
    distributable under the GPL or Artistic License. Modifications to and
    use of this software must adhere to one of these licenses. Changes to
    the code should be noted as such and this notification (as well as the
    above copyright information) must remain intact on all copies of the
    code.

    Additionally, while the author is actively developing this code,
    notification of any intended changes or extensions would be most helpful
    in avoiding repeated work for all parties involved. Please contact the
    author with any such development plans.

SEE ALSO
      CAD::Drawing
      CAD::Calc
      Math::Vec

Changes
      0.10 First public release
      0.11 Minor improvements

Methods
Extents Calculations
  OrthExtents

    Calculates the extents of a group of objects (selected according to
    select_addr()) and returns an array: [xmin,xmax],[ymin,ymax].

      @extents = $drw->OrthExtents(\%opts);

  getExtentsRec

    Alias to OrthExtents() which returns a polyline-form array of points
    (counter clockwise from lower-left) describing a rectangle.

      @rec = $drw->getExtentsRec(\%opts);

  EntOrthExtents

    Gets the orthographic extents of the object at $addr. Returns
    [\@xpts,\@y_pts] (leaving you to sort through them and find which is min
    or max.)

      @extents = $drw->EntOrthExtents($addr);

  @orthfunc

    List of hash references containing code references to reduce duplication
    and facilitate natural flow (rather than ifififif statements.)

Planar Geometry Methods
  offset

    Intended as any-object offset function (not easy).

    $dist is negative to offset outward

      $drw->offset($dist);

  divide

      $drw->divide();

  area

      $drw->area($addr);

Line Manipulations
  pline_to_ray

    Transforms a polyline with a nubbin into a ray (line with direction.)

      $line_addr = $drw->pline_to_ray($pline_addr);

  trim_both

    Trims two lines to their intersection.

      $drw->trim_both($addr1, $addr2, $tol);

    See CAD::Calc::line_intersection()

Coordinate Transforms
    Switch between coordinate system representations.

  to_ocs

    Change the objects coordinates into the object coordinate system.

    Both of these are relatively quick. A simple test shows that one point
    can be taken back and forth at about 2KHz, so don't be afraid to use
    them.

      $drw->to_ocs($addr);

  to_wcs

    Change the objects coordinates into the world coordinate system.

      $drw->to_wcs($addr);

  flatten

    Puts the object in the wcs, zeros all z-coordinates and deletes the
    normal vector. Note that this is fine for projecting polylines and
    lines, but may not be what you want if you are trying to make a circle
    into an ellipse (at least not yet.)

      $drw->flatten($addr);

Functions
    Non-OO internal-use functions.

  _ocs_axes

    Returns the x,y, and z axes for the ocs described by @normal. These will
    have arbitrary lengths.

      @local_axes = _ocs_axes(@normal);

  _wcs_axes

    Returns the x,y, and z axes for the world coordinate system in terms of
    the @ocs_axes.

      @trs_axes = _wcs_axes(@ocs_axes);