判断点是否在多边形内部

pointinpolygon.py

# -*- coding: utf-8 -*-
"""判断点是否在多边形内部

参考: https://github.com/flaviamissi/Point-Inside-Polygon
"""

def get_number_of_intersected_sides(self, point, polygon):
	crossed_by_left = 0; crossed_by_right = 0
	for i in range(1, len(polygon)):
		if point[1] in range(polygon[i-1][1], polygon[i][1]+1) or point[1] in range(polygon[i][1], polygon[i-1][1]+1):
			if point[0] > polygon[i-1][0] and point[0] > polygon[i][0]:
				crossed_by_left += 1
			else:
				crossed_by_right += 1
	return {"left" : crossed_by_left, "right" : crossed_by_right}

def point_inside_polygon(self, point, polygon):
	crossed = self.get_number_of_intersected_sides(point)
	return crossed["left"] % 2 != 0 and crossed["right"] % 2 != 0