New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/geometry/segment2d.hpp

@@ -0,0 +1,50 @@
+#pragma once
+
+#include "geometry/point2d.hpp"
+
+#include <string>
+
+namespace m2
+{
+struct IntersectionResult
+{
+  enum class Type
+  {
+    Zero,
+    One,
+    Infinity
+  };
+
+  explicit IntersectionResult(Type type) : m_type(type) { ASSERT_NOT_EQUAL(m_type, Type::One, ()); }
+  explicit IntersectionResult(PointD const & point) : m_point(point), m_type(Type::One) {}
+
+  PointD m_point;
+  Type m_type;
+};
+
+struct Segment2D
+{
+  Segment2D() = default;
+  Segment2D(PointD const & u, PointD const & v) : m_u(u), m_v(v) {}
+
+  PointD const Dir() const { return m_v - m_u; }
+
+  PointD m_u;
+  PointD m_v;
+};
+
+bool IsPointOnSegmentEps(PointD const & pt, PointD const & p1, PointD const & p2, double eps);
+bool IsPointOnSegment(PointD const & pt, PointD const & p1, PointD const & p2);
+
+/// \returns true if segments (p1, p2) and (p3, p4) are intersected and false otherwise.
+bool SegmentsIntersect(PointD const & p1, PointD const & p2, PointD const & p3,
+                       PointD const & p4);
+
+/// \breif Intersects two segments and finds an intersection point if any.
+/// \note |eps| applies for collinearity and for PointD errors.
+IntersectionResult Intersect(Segment2D const & seg1, Segment2D const & seg2, double eps);
+
+std::string DebugPrint(Segment2D const & s);
+std::string DebugPrint(IntersectionResult::Type type);
+std::string DebugPrint(IntersectionResult const & result);
+}  // namespace m2