RE: Point inside a plygon? and PointInsidePolyhedronQ
- To: mathgroup at smc.vnet.net
- Subject: [mg25374] RE: [mg25239] Point inside a plygon? and [mg24992]PointInsidePolyhedronQ
- From: "David Park" <djmp at earthlink.net>
- Date: Sun, 24 Sep 2000 16:29:08 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Dear MathGroup, It looks to me that Will Self's windingNumber procedure is the best so far. He has pointed out a second counter example where the line intersection method does fail. This is when the test line is outside the polygon but tangent to it at a vertex. My routine counts one (false) crossing. Another counter example would be when the test line crosses the polygon by lying exactly on top of an edge. My routine would not count it as a crossing. The line crossing method is very nice mathematics. It is not quite so convenient computationally. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/