Some inputs causing infinite recursion

[rproepp]

Hi, the following input causes an infinite recursion, resulting in a stack overflow:

#include "ConcavePolygon.h"

int main()
{
    std::vector<cxd::Vertex > vertices =
    {
        cxd::Vec2({0.500000000000, 0.500000000000}),
        cxd::Vec2({0.500000000000, -0.498161792755}),
        cxd::Vec2({-0.497167110443, -0.498161792755}),
        cxd::Vec2({-0.497167110443, 0.277573525906}),
        cxd::Vec2({-0.415014147758, 0.273897051811}),
        cxd::Vec2({-0.349858343601, 0.297794103622}),
        cxd::Vec2({-0.168555259705, 0.435661762953}),
        cxd::Vec2({-0.151558041573, 0.465073525906}),
        cxd::Vec2({-0.151558041573, 0.500000000000}),
        cxd::Vec2({-0.072237968445, 0.500000000000}),
        cxd::Vec2({-0.043909311295, 0.430147051811}),
        cxd::Vec2({-0.024079322815, 0.408088237047}),
        cxd::Vec2({0.038243621588, 0.376838237047}),
        cxd::Vec2({0.109065175056, 0.367647051811}),
        cxd::Vec2({0.160056650639, 0.369485288858}),
        cxd::Vec2({0.245042502880, 0.393382370472}),
        cxd::Vec2({0.301699697971, 0.441176474094}),
        cxd::Vec2({0.332861185074, 0.500000000000})
    };

    cxd::ConcavePolygon concavePoly(vertices);
    concavePoly.convexDecomp(0);

    std::vector<cxd::ConcavePolygon> subPolygonList;
    concavePoly.returnLowestLevelPolys(subPolygonList);

    std::cout << "Num Polys: " << subPolygonList.size() << std::endl;

    return 0;
}

[rproepp]

I looked into this a bit more. The vertices mentioned above reduce to the following list before entering the infinite recursion:

    std::vector<cxd::Vertex> vertices =
    {
        cxd::Vec2({ 0.25093948401191, 0.3727616036061424 }),
        cxd::Vec2({ 0.109065175056, 0.367647051811 }),
        cxd::Vec2({ 0.06879750720276288, 0.3615178925897086 }),
        cxd::Vec2({ -0.024079322815, 0.408088237047 }),
        cxd::Vec2({ -0.043909311295, 0.430147051811 }),
        cxd::Vec2({ -0.07223796844499999, 0.5 }),
        cxd::Vec2({ -0.151558041573, 0.5 }),
        cxd::Vec2({ -0.151558041573, 0.465073525906 }),
        cxd::Vec2({ -0.168555259705, 0.435661762953 }),
        cxd::Vec2({ -0.349858343601, 0.297794103622 }),
        cxd::Vec2({ -0.415014147758, 0.273897051811 }),
        cxd::Vec2({ -0.497167110443, 0.277573525906 }),
        cxd::Vec2({ -0.497167110443, -0.498161792755 }),
        cxd::Vec2({ 0.5, -0.4981617927550001 })
    }

Some of the points are almost collinear, so I reduced the tolerance value in LineSegment::intersects() to 1e-5, that got rid of the problem for this case.