Repo created

libs/geometry/algorithm.cpp

@@ -0,0 +1,77 @@
+#include "geometry/algorithm.hpp"
+#include "geometry/triangle2d.hpp"
+
+#include "base/logging.hpp"
+
+namespace m2
+{
+// CalculatePolyLineCenter -------------------------------------------------------------------------
+void CalculatePolyLineCenter::operator()(m2::PointD const & pt)
+{
+  m_length += (m_poly.empty() ? 0.0 : m_poly.back().m_p.Length(pt));
+  m_poly.emplace_back(pt, m_length);
+}
+
+PointD CalculatePolyLineCenter::GetResult() const
+{
+  using TIter = std::vector<Value>::const_iterator;
+
+  double const l = m_length / 2.0;
+
+  TIter e = lower_bound(m_poly.begin(), m_poly.end(), Value(m2::PointD(0, 0), l));
+  if (e == m_poly.begin())
+  {
+    /// @todo It's very strange, but we have linear objects with zero length.
+    LOG(LWARNING, ("Zero length linear object"));
+    return e->m_p;
+  }
+
+  TIter b = e - 1;
+
+  double const f = (l - b->m_len) / (e->m_len - b->m_len);
+
+  // For safety reasons (floating point calculations) do comparison instead of ASSERT.
+  if (0.0 <= f && f <= 1.0)
+    return (b->m_p * (1 - f) + e->m_p * f);
+  else
+    return ((b->m_p + e->m_p) / 2.0);
+}
+
+// CalculatePointOnSurface -------------------------------------------------------------------------
+CalculatePointOnSurface::CalculatePointOnSurface(m2::RectD const & rect)
+  : m_rectCenter(rect.Center())
+  , m_center(m_rectCenter)
+  , m_squareDistanceToApproximate(std::numeric_limits<double>::max())
+{}
+
+void CalculatePointOnSurface::operator()(PointD const & p1, PointD const & p2, PointD const & p3)
+{
+  if (m_squareDistanceToApproximate == 0.0)
+    return;
+  if (m2::IsPointInsideTriangle(m_rectCenter, p1, p2, p3))
+  {
+    m_center = m_rectCenter;
+    m_squareDistanceToApproximate = 0.0;
+    return;
+  }
+  PointD triangleCenter(p1);
+  triangleCenter += p2;
+  triangleCenter += p3;
+  triangleCenter = triangleCenter / 3.0;
+
+  double triangleDistance = m_rectCenter.SquaredLength(triangleCenter);
+  if (triangleDistance <= m_squareDistanceToApproximate)
+  {
+    m_center = triangleCenter;
+    m_squareDistanceToApproximate = triangleDistance;
+  }
+}
+
+// CalculateBoundingBox ----------------------------------------------------------------------------
+void CalculateBoundingBox::operator()(PointD const & p)
+{
+  // Works just fine. If you don't belive me, see geometry/rect2d.hpp.
+  // Pay attention to MakeEmpty and Add functions.
+  m_boundingBox.Add(p);
+}
+}  // namespace m2