C++博客-T9的空间 -随笔分类-计算几何http://www.cppblog.com/xieshuo/category/8202.htmlYOU WILL NEVER WALK ALONE!zh-cnSat, 25 Oct 2008 08:35:11 GMTSat, 25 Oct 2008 08:35:11 GMT60pku 1269 (平面两直线的位置关系)http://www.cppblog.com/xieshuo/archive/2008/09/24/62711.html Torres TorresWed, 24 Sep 2008 13:29:00 GMThttp://www.cppblog.com/xieshuo/archive/2008/09/24/62711.htmlhttp://www.cppblog.com/xieshuo/comments/62711.htmlhttp://www.cppblog.com/xieshuo/archive/2008/09/24/62711.html#Feedback0http://www.cppblog.com/xieshuo/comments/commentRss/62711.htmlhttp://www.cppblog.com/xieshuo/services/trackbacks/62711.html阅读全文

Torres 2008-09-24 21:29 发表评论
]]>判断点是否在多边形中http://www.cppblog.com/xieshuo/archive/2008/09/23/62625.html Torres TorresTue, 23 Sep 2008 12:51:00 GMThttp://www.cppblog.com/xieshuo/archive/2008/09/23/62625.htmlhttp://www.cppblog.com/xieshuo/comments/62625.htmlhttp://www.cppblog.com/xieshuo/archive/2008/09/23/62625.html#Feedback0http://www.cppblog.com/xieshuo/comments/commentRss/62625.htmlhttp://www.cppblog.com/xieshuo/services/trackbacks/62625.html我就叫他射线法吧
基本步骤：

１，过ｐ点垂直向上作一条射线

２，判断此射线与ｎ边形ｎ条边的交点

３，把所有交点相加，如果是奇数则说明在多边形内，否则在多边形外

思路非常的简单，另外说明一下几种特殊的情况：

１，射线与多边形的顶点相交；比如射线过多边形的Pi点，则如果Pi-1和Pi+1在此射线的异侧，此交点可以算一个，如果此两点在射线的同侧，则此交点不计。此结论非常简单，画个图应该就能明白了

２，ｐ点在多边形的某一条边上；也认为ｐ在多边形中

３，ｐ不在多边形的边上，但ｐ的射线与多边形的某一条边重合；比如与Pi,Pi+1线段重合，则如果Pi-1和Pi+2在射线的两侧，此情况也算一个交点，否则此情况不计交点



Torres 2008-09-23 20:51 发表评论
]]>pku1113（凸包的周长）http://www.cppblog.com/xieshuo/archive/2008/09/07/61207.html Torres TorresSun, 07 Sep 2008 04:57:00 GMThttp://www.cppblog.com/xieshuo/archive/2008/09/07/61207.htmlhttp://www.cppblog.com/xieshuo/comments/61207.htmlhttp://www.cppblog.com/xieshuo/archive/2008/09/07/61207.html#Feedback0http://www.cppblog.com/xieshuo/comments/commentRss/61207.htmlhttp://www.cppblog.com/xieshuo/services/trackbacks/61207.html阅读全文

Torres 2008-09-07 12:57 发表评论
]]>pku2187（凸包）http://www.cppblog.com/xieshuo/archive/2008/09/07/61204.html Torres TorresSun, 07 Sep 2008 04:54:00 GMThttp://www.cppblog.com/xieshuo/archive/2008/09/07/61204.htmlhttp://www.cppblog.com/xieshuo/comments/61204.htmlhttp://www.cppblog.com/xieshuo/archive/2008/09/07/61204.html#Feedback0http://www.cppblog.com/xieshuo/comments/commentRss/61204.htmlhttp://www.cppblog.com/xieshuo/services/trackbacks/61204.html阅读全文

Torres 2008-09-07 12:54 发表评论
]]>HUST1175（多边形相交模板）http://www.cppblog.com/xieshuo/archive/2008/09/07/61202.html Torres TorresSun, 07 Sep 2008 04:51:00 GMThttp://www.cppblog.com/xieshuo/archive/2008/09/07/61202.htmlhttp://www.cppblog.com/xieshuo/comments/61202.htmlhttp://www.cppblog.com/xieshuo/archive/2008/09/07/61202.html#Feedback0http://www.cppblog.com/xieshuo/comments/commentRss/61202.htmlhttp://www.cppblog.com/xieshuo/services/trackbacks/61202.html阅读全文

Torres 2008-09-07 12:51 发表评论
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