https://docs.opencv.org/2.4/modules/imgproc/doc/structural_analysis_and_shape_descriptors.html?highlight=pointpolygontest#pointpolygontest
官方文档
pointPolygonTest
判断一个点与所给轮廓的位置关系。
Parameters:
- contour – Input contour. 轮廓
- pt – Point tested against the contour. 点
- measureDist – If true, the function estimates the signed distance from the point to the nearest contour edge. Otherwise, the function only checks if the point is inside a contour or not. true则返回距离否则返回 1 0 -1
返回正数为在轮廓内，负数在轮廓外，0在轮廓上