CGAL: Intersection between a segment and a polygon?

问题

I have a set of polygons and I want to test intersection between it and a segment. I checked the manual but I cannot find a matching function. The intersection between points, lines, segments, triangles, planes do exist. And the intersection between polygons are also there. My question is:

Is there such a function?
If not, does it mean I need to break down the polygons into segments and do intersection among these segments? (The reason that I am reluctant to do this is, I thought CGAL might in fact use this way to do intersections between polygons. How come there is no such a function for intersecting a line and a polygon?) Or is there any other better way to do it?

回答1:

The easiest method is to create a Polygon_set_2 object which may contain several polygons. To test an intersection of an external polygon with this set you simply apply the do_intersect method.

For example:

typedef CGAL::Polygon_set_2<Kernel, std::vector<Kernel::Point_2>> Polygon_set_2;
Polygon_set_2 ps;
Polygon_2     poly;
Polygon_2     line; // line is a polygon defined by 2 points

ps.insert(poly);
bool intersect = ps.do_intersect(line);