geometry::union_ yields degenerated results

[Danvil <danvil@…>]

The following data gives wrong results with geometry::union.

float data1[][2] = {{0,0}, {-0.3681253195,0.9297761917}, {2.421203136,2.034152031}, {2.789328575,1.104375958}, {0,0}};
float data2[][2] = {{2.76143527,1.093332171}, {2.076887131,1.822299719}, {4.263789177,3.875944376}, {4.948337555,3.146976948}, {2.76143527,1.093332171}};

polygon_t p1, p2;
boost::geometry::append(p1, data1);
boost::geometry::append(p2, data2);

std::vector<polygon_t> output;
boost::geometry::union_(p1, p2, output);

Please find attached the whole main file and program output.

[Danvil <danvil@…>]

Actually union(p1,p2) yields a degenerated polygon while union(p2,p1) gives the correct result. In my use case, wrong results occur in ~0.5% of the cases.

[Barend Gehrels]

(In [83481]) [geometry] Fix ticket 7462, degenerate union for float. This was caused by two distances being wrong (by floating point precision). We now use earlier the alternative sort method (sorting on left/right), using relaxed_epsilon. This fixes the cause.

[Barend Gehrels]

(In [83482]) [geometry] Fix ticket 7462, (unit tests)

[anonymous]

Replying to barendgehrels:

(In [83482]) [geometry] Fix ticket 7462, (unit tests)

Thanks for fixing this!