Weiler–Atherton clipping algorithm: Difference between revisions

Revision as of 19:12, 23 July 2015

Revision as of 19:15, 23 July 2015

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- The algorithm can support holes (as counter-clockwise polygons wholly inside their parent polygon), but requires additional algorithms to decide which polygons are holes. Then, merging of polygons can be performed by a variant of the algorithm.

== The Algorithm ==

Two lists are created from the coordinates of each polygons A and BSuppose, where A is the clipclipping polygon/region/area, and, B is the candidate polygon/subject polygon/polygon to be clipped.

First, two lists are created where one list contains the vertices of the clipping polygon A and the another list contains the vertices of the subject polygon B.

The list entries are labelled as either inside or outside the other polygon. Various strategies can be used to improve the speed of this labelling, and to avoid needing to proceed further.