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[Pol Monsó Purtí <>]

I've been trying to retrieve the intersection of two polygons.

I always get pre_condition exceptions which I can't seem to resolve and I'm starting to wonder wether it's not possible to make polygon_2 intersections without the exact constructs.

Fiddleing I've tried making two simple polygons as well, they too provoke exceptions, thus why I'm starting to suspect the exact constructs are necessary.

Attached the ascii polygon's points.

Using the original ones I get the exception:
precondition violation!

_expression_ : (m_traits.compare_y_at_x_2_object()(p, cv1) == EQUAL) && (m_traits.compare_y_at_x_2_object()(p, cv2) == EQUAL)

File : C:\Users\Pol\codeheli\portho\libs\cgal\Arrangement_on_surface_2\include\CGAL/Arr_segment_traits_2.h

Line : 580

The artificial ones are:
Polytype bbox1;
989703.429, 6583768.645
976393.049, 6583768.645
976493.049, 6587550.584
989603.429, 6587550.584
976393.049, 6587650.584
989703.429, 6587650.584

Polytype bbox2;
985000, 6584000
980000, 6584000
980000, 6587000
985000, 6587000

Using the fake ones I get a warning and an exception:
CGAL warning: check violation!

_expression_ : valid_orientation

File : C:\Users\Pol\codeheli\portho\libs\cgal\Boolean_set_operations_2\include\CGAL/Boolean_set_operations_2/Gps_polygon_validation.h

Line : 312

CGAL error: precondition violation!

_expression_ : is_valid_unknown_polygon(p, t)

File : C:\Users\Pol\codeheli\portho\libs\cgal\Boolean_set_operations_2\include\CGAL/General_polygon_set_on_surface_2.h

Line : 45

976959.417000 6587037.011000
977119.843000 6587111.914000
977345.151000 6587245.755000
977582.432000 6587386.441000
977679.198000 6587444.240000
977835.664000 6587420.459000
978073.853000 6587385.457000
978265.771000 6587357.019000
978428.471000 6587376.327000
978691.486000 6587407.141000
978939.235000 6587435.734000
979222.620000 6587402.241000
979632.882000 6587353.202000
980017.341000 6587308.044000
980304.320000 6587274.091000
980588.134000 6587240.174000
980883.767000 6587032.365000
981185.238000 6586820.773000
981459.902000 6586627.875000
981797.456000 6586391.166000
982083.252000 6586190.804000
982372.593000 6585987.426000
982511.373000 6585710.524000
982643.426000 6585449.003000
983524.023000 6584782.521000
983785.791000 6584715.725000
984174.247000 6584615.053000
984325.281000 6584576.498000
984465.394000 6584540.547000
984588.653000 6584508.607000
984797.196000 6584454.987000
985015.238000 6584445.812000
985157.557000 6584439.395000
985378.154000 6584430.352000
986114.249000 6584398.395000
986851.938000 6584366.932000
987385.343000 6584345.571000
987623.235000 6584346.475000
987970.493000 6584350.989000
988124.994000 6584353.233000
988456.666000 6584358.113000
988811.900000 6584362.478000
988998.487000 6584168.451000
989094.182000 6584068.883000
989540.685000 6583868.645000
989603.429000 6583977.620000
989509.884000 6584019.571000
989498.295000 6583999.443000
989153.996000 6584153.847000
989072.017000 6584239.143000
988854.808000 6584465.012000
988455.290000 6584460.103000
988123.502000 6584455.223000
987969.089000 6584452.979000
987622.379000 6584448.473000
987387.191000 6584447.579000
986856.152000 6584468.846000
986118.635000 6584500.301000
985382.454000 6584532.262000
985161.943000 6584541.301000
985019.680000 6584547.716000
984812.204000 6584556.445000
984614.147000 6584607.369000
984490.862000 6584639.317000
984350.571000 6584675.314000
984199.655000 6584713.837000
983811.195000 6584814.511000
983569.175000 6584876.267000
982723.826000 6585516.073000
982602.493000 6585756.364000
982452.269000 6586056.098000
982141.856000 6586274.288000
981856.014000 6586474.682000
981518.494000 6586711.367000
981243.848000 6586904.253000
980942.395000 6587115.833000
980625.762000 6587338.404000
980316.364000 6587375.377000
980029.283000 6587409.342000
979644.884000 6587454.494000
979234.658000 6587503.529000
978939.375000 6587538.428000
978679.704000 6587508.459000
978416.527000 6587477.625000
978267.263000 6587459.911000
978088.743000 6587486.365000
977850.742000 6587521.339000
977658.326000 6587550.584000
977530.270000 6587474.095000
977293.095000 6587333.471000
977072.103000 6587202.194000
976916.149000 6587129.379000
976566.579000 6586964.980000
976493.049000 6586949.058000
976501.791000 6586900.137000
976521.929000 6586783.526000
976649.951000 6586805.636000
976638.490000 6586886.182000984074.879320 6583868.645000 100 0 0
984116.614161 6584017.252624 100 0 0
984247.601181 6584517.835493 100 0 0
984248.202878 6584521.052010 100 0 0
984250.457990 6584732.713229 100 0 0
984184.637360 6584607.792833 100 0 0
983953.256252 6583868.645000 100 0 0