fix cases of bad diagonals in the split routine

ports
mapbox/earcut@d13c8dc
47f27ce1

Author: mourner

README.md

@@ -106,4 +106,4 @@ Import the project from https://github.com/mapbox/earcut.hpp.git and you should
 
 ## Status
 
-This is currently based on [earcut 2.0.9](https://github.com/mapbox/earcut#209-mar-10-2016).
+This is currently based on [earcut 2.1.1](https://github.com/mapbox/earcut#211-mar-17-2016).

include/earcut.hpp

@@ -645,8 +645,8 @@ bool Earcut<N>::pointInTriangle(double ax, double ay, double bx, double by, doub
 // check if a diagonal between two polygon nodes is valid (lies in polygon interior)
 template <typename N>
 bool Earcut<N>::isValidDiagonal(Node* a, Node* b) {
-    return equals(a, b) || (a->next->i != b->i && a->prev->i != b->i && !intersectsPolygon(a, b) &&
-           locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b));
+    return a->next->i != b->i && a->prev->i != b->i && !intersectsPolygon(a, b) &&
+           locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b);
 }
 
 // signed area of a triangle
@@ -664,6 +664,8 @@ bool Earcut<N>::equals(const Node* p1, const Node* p2) {
 // check if two segments intersect
 template <typename N>
 bool Earcut<N>::intersects(const Node* p1, const Node* q1, const Node* p2, const Node* q2) {
+    if ((equals(p1, q1) && equals(p2, q2)) ||
+        (equals(p1, q2) && equals(p2, q1))) return true;
     return area(p1, q1, p2) > 0 != area(p1, q1, q2) > 0 &&
            area(p2, q2, p1) > 0 != area(p2, q2, q1) > 0;
 }

test/fixtures/bad_diagonals.cpp

@@ -0,0 +1,15 @@
+// This file is auto-generated, manual changes will be lost if the code is regenerated.
+
+#include "geometries.hpp"
+
+MAPBOX_MSVC_DISABLE_OPTIMIZATION()
+namespace mapbox {
+namespace fixtures {
+
+const IntegerPolygon bad_diagonals = {
+    {{440,4152},{440,4208},{296,4192},{368,4192},{400,4200},{400,4176},{368,4192},{296,4192},{264,4200},{288,4160},{296,4192}},
+};
+
+}
+}
+MAPBOX_MSVC_ENABLE_OPTIMIZATION()

test/fixtures/geometries.hpp

@@ -35,6 +35,7 @@ using DoublePolygon = Polygon<DoublePoint>;
 
 
 extern const ShortPolygon park;
+extern const IntegerPolygon bad_diagonals;
 extern const IntegerPolygon bad_hole;
 extern const IntegerPolygon building;
 extern const IntegerPolygon degenerate;

test/test.cpp

@@ -120,7 +120,7 @@ int main() {
     areaTest<int>("water3", mapbox::fixtures::water3, 197);
     areaTest<int>("water3b", mapbox::fixtures::water3b, 25);
     areaTest<int>("water4", mapbox::fixtures::water4, 705);
-    areaTest<int>("water_huge", mapbox::fixtures::water_huge, 5173, 0.0011, 0.0002);
+    areaTest<int>("water_huge", mapbox::fixtures::water_huge, 5174, 0.0011, 0.0002);
     areaTest<int>("water_huge2", mapbox::fixtures::water_huge2, 4461, 0.0028, 0.00015);
     areaTest<int>("degenerate", mapbox::fixtures::degenerate, 0);
     areaTest<int>("bad_hole", mapbox::fixtures::bad_hole, 42, 0.042, 0.0022);
@@ -144,6 +144,7 @@ int main() {
     areaTest<double>("issue52", mapbox::fixtures::issue52, 109, 1e-13);
     areaTest<double>("eberly3", mapbox::fixtures::eberly_3, 73, 1e-13);
     areaTest<double>("shared-points", mapbox::fixtures::shared_points, 4);
+    areaTest<double>("bad-diagonals", mapbox::fixtures::bad_diagonals, 7);
 
     return 0;
 }