protected Lineside LeftOfLine(IPoint pPt) { double startx=StartX; double starty=StartY; double endx=EndX; double endy = EndY; /* //double tmpx = (p1.x - p2.x) / (p1.y - p2.y) * (p.y - p2.y) + p2.x; double tmpx = (endx - pPt.X) / (endy - pPt.Y) * (starty - pPt.Y) + pPt.X; if (tmpx > startx)//当tmpx>p.x的时候,说明点在线的左边,小于在右边,等于则在线上。 return Lineside.Left; else if (tmpx < startx) return Lineside.Right;*/ //两点p1(x1,y1),p2(x2,y2),判断点p(x,y) // (y1 – y2) * x + (x2 – x1) * y + x1 * y2 – x2 * y1 double tmp = (starty - endy) * pPt.X + (endx - startx) * pPt.Y + startx * endy -endx * starty; if (tmp > 0) return Lineside.Left; else if (tmp < 0) return Lineside.Right; return Lineside.Online; }
判断点在线的一侧
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转载自blog.csdn.net/study_gis/article/details/80352683
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