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https://issues.apache.org/jira/browse/LUCENE-7198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15234911#comment-15234911
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Karl Wright commented on LUCENE-7198:
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Some analysis of the problem shows that a series of coplanar points will likely
already work. The reason is that points on an edge are considered to be
in-set. Coplanarity is only approximate, but the convexity check guarantees
that even coplanar points are truly convex (or concave).
The bad cases are as follows:
(1) Two edges are coplanar and one of the two edges is internal while the other
isn't. In that case, if there's enough deviance from coplanarity, the entire
edge will be checked for intersection, despite the fact that only part of it
should be. This will cause over-reporting of OVERLAPS situations, which is
acceptable.
(2) An intersection point is just outside the edge, and the coplanar edge
removes it from consideration. The convexity guarantee, however, insures that
the minimum resolutiion for the point membership in the coplanar edge will be
sufficient.
So I think we're actually good here, and messing with the code is probably not
called for.
> Co-linear points in a convex or concave polygon will not properly detect
> intersections
> --------------------------------------------------------------------------------------
>
> Key: LUCENE-7198
> URL: https://issues.apache.org/jira/browse/LUCENE-7198
> Project: Lucene - Core
> Issue Type: Bug
> Components: modules/spatial3d
> Affects Versions: master
> Reporter: Karl Wright
> Assignee: Karl Wright
>
> When two or more points in a convex or concave polygon are colinear, the
> polygon won't properly detect intersections. In order to work, the colinear
> segments must not interfere with one another during intersection detection.
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