Repo created

libs/geometry/robust_orientation.cpp

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+#include "geometry/robust_orientation.hpp"
+
+#include "base/macros.hpp"
+
+#include <algorithm>
+
+extern "C"
+{
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wconditional-uninitialized"
+#include "3party/robust/predicates.c"
+#pragma clang diagnostic pop
+#else
+#include "3party/robust/predicates.c"
+#endif
+}
+
+namespace m2::robust
+{
+bool Init()
+{
+  exactinit();
+  return true;
+}
+
+double OrientedS(PointD const & p1, PointD const & p2, PointD const & p)
+{
+  static bool const res = Init();
+  ASSERT_EQUAL(res, true, ());
+  UNUSED_VALUE(res);
+
+  double a[] = {p1.x, p1.y};
+  double b[] = {p2.x, p2.y};
+  double c[] = {p.x, p.y};
+
+  return orient2d(a, b, c);
+}
+
+bool IsSegmentInCone(PointD const & v, PointD const & v1, PointD const & vPrev, PointD const & vNext)
+{
+  double const cpLR = OrientedS(vPrev, vNext, v);
+
+  if (cpLR == 0.0)
+  {
+    // Points vPrev, v, vNext placed on one line;
+    // use property that polygon has CCW orientation.
+    return OrientedS(vPrev, vNext, v1) > 0.0;
+  }
+
+  if (cpLR < 0.0)
+  {
+    // vertex is concave
+    return OrientedS(v, vPrev, v1) < 0.0 && OrientedS(v, vNext, v1) > 0.0;
+  }
+  // vertex is convex
+  return OrientedS(v, vPrev, v1) < 0.0 || OrientedS(v, vNext, v1) > 0.0;
+}
+}  // namespace m2::robust