2007-12-08 18:19:48 +00:00
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Generic Polygon Clipper (gpc) Revision History
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==============================================
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v2.32 17th Dec 2004
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---------------------
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Fixed occasional memory leak occurring when processing some
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degenerate polygon arrangements.
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Added explicit type casting to memory allocator in support of
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increased code portability.
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v2.31 4th Jun 1999
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---------------------
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Separated edge merging measure based on a user-defined GPC_EPSILON
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value from general numeric equality testing and ordering, which now
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uses direct arithmetic comparison rather an EPSILON based proximity
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test.
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Fixed problem with numerical equality test during construction of
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local minima and scanbeam tables, leading to occasional crash.
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Fixed hole array memory leak in gpc_add_contour.
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Fixed uninitialised hole field bug in gpc_polygon_clip result.
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v2.30 11th Apr 1999
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---------------------
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Major re-write.
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Minor API change: additional 'hole' array field added to gpc_polygon
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datatype to indicate which constituent contours are internal holes,
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and which form external boundaries.
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Minor API change: additional 'hole' argument to gpc_add_contour
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to indicate whether the new contour is a hole or external contour.
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Minor API change: additional parameter to gpc_read_polygon and
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gpc_write_polygon to indicate whether or not to read or write
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contour hole flags.
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Fixed NULL pointer bug in add/merge left/right operations.
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Fixed numerical problem in intersection table generation.
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Fixed zero byte malloc problem.
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Fixed problem producing occasional 2 vertex contours.
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Added bounding box test optimisations.
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Simplified edge bundle creation, detection of scanbeam internal
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edge intersections and tristrip scanbeam boundary code.
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Renamed 'class' variable to be C++ friendly.
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v2.22 17th Oct 1998
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---------------------
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Re-implemented edge interpolation and intersection calculations
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to improve numerical robustness.
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Simplified setting of GPC_EPSILON.
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v2.21 19th Aug 1998
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---------------------
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Fixed problem causing occasional incorrect output when processing
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self-intersecting polygons (bow-ties etc).
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Removed bug which may lead to non-generation of uppermost triangle
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in tristrip output.
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v2.20 26th May 1998
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---------------------
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Major re-write.
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Added exclusive-or polygon set operation.
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Replaced table-based processing of edge intersections with
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rule-based system.
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Replaced two-pass approach to scanbeam interior processing with
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single pass method.
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v2.10a 14th May 1998
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---------------------
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Minor bug-fixes to counter some v2.10 reliability problems.
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v2.10 11th May 1998
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---------------------
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Major re-write.
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Incorporated edge bundle processing of AET to overcome coincident
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edge problems present in previous releases.
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Replaced Vatti's method for processing scanbeam interior regions
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with an adapted version of the scanbeam boundary processing
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algorithm.
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v2.02 16th Apr 1998 (unreleased)
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----------------------------------
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Fixed internal minimum vertex duplication in gpc_polygon_clip
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result.
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Improved line intersection code discourage superfluous
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intersections near line ends.
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Removed limited precision number formatting in gpc_write_polygon.
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Modification to allow subject or clip polygon to be reused as the
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result in gpc_polygon_clip without memory leakage.
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v2.01 23rd Feb 1998
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---------------------
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Removed bug causing duplicated vertices in output polygon.
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Fixed scanbeam table index overrun problem.
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v2.00 25th Nov 1997
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---------------------
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Major re-write.
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Replaced temporary horizontal edge work-around (using tilting)
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with true horizontal edge handling.
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Trapezoidal output replaced by tristrips.
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gpc_op constants now feature a `GPC_' prefix.
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Data structures now passed by reference to gpc functions.
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Replaced AET search by proxy addressing in polygon table.
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Eliminated most (all?) coincident vertex / edge crashes.
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v1.02 18th Oct 1997 (unreleased)
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----------------------------------
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Significantly reduced number of mallocs in build_lmt.
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Scanbeam table now built using heapsort rather than insertion
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sort.
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v1.01 12th Oct 1997
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---------------------
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Fixed memory leak during output polygon build in
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gpc_clip_polygon.
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Removed superfluous logfile debug code.
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Commented out malloc counts.
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Added missing horizontal edge tilt-correction code in
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gpc_clip_polygon.
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v1.00 8th Oct 1997
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--------------------
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First release.
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