Autocad intersection test -> polygone vs point

    static bool isPointInside(AcDbPolyline &polyline, AcGePoint2d &point)
    {
        // ALGORITHM: Build a horizontal line starting at the
        // left side of the polyline and ending in the point
        // to be checked. Then count the number of intersections.
        // An even count means the point is contained within the
        // polyline, an odd therefore indicates that the point is
        // outside of the polygone.

        AcDbExtents extents;
        polyline.getGeomExtents(extents);

        AcGePoint3d min = extents.minPoint();

        // Do a fast check first. If the point is already outside the bouding area
        // we can stop right here.
        if (point.x < min.x || point.x > extents.maxPoint().x
            || point.y < min.y || point.y > extents.maxPoint().x)
            return false;

        // This is our intersection line, we need to cound the intersections for this
        AcGeLine2d line(AcGePoint2d(min.x, point.y), point);

        // Iterate over all points and build lines to check intersection with
        Adesk::uint intersectionCount = 0;
        for (Adesk::uint i = 0; i < polyline.numVerts() - 1; ++i)
        {
            // check with line from pnts[i] to pnts[i+1]
            AcGeLineSeg2d test;
            polyline.getLineSegAt(i, test);

            AcGePoint2d intersection;
            if (test.intersectWith(line, intersection))
                // We need to test here again if reported intersection if correct
                // as of the method tends to ignore the line boundaries.
                // Checking only the x-axis is suitable here.
                if ((min.x <= intersection.x && intersection.x <= point.x) ||
                     point.x <= intersection.x && intersection.x <= min.x)
                    intersectionCount++;
        }

        // Even intersectionCount here means the point is intersecting
        return intersectionCount % 2 == 1;
    }