From 01835487d022ad6d589df0322c7b7a1f47177b46 Mon Sep 17 00:00:00 2001
From: "r.kuznetsov" <r.kuznetsov@corp.mail.ru>
Date: Fri, 4 Mar 2016 17:00:11 +0300
Subject: [PATCH] Optimized spline clipping, increased tile size

---
 drape_frontend/tile_key.cpp               |  3 +-
 drape_frontend/tile_utils.cpp             |  3 +-
 geometry/clipping.cpp                     | 73 ++++++++++++-----------
 geometry/geometry_tests/clipping_test.cpp | 13 ++++
 4 files changed, 56 insertions(+), 36 deletions(-)

diff --git a/drape_frontend/tile_key.cpp b/drape_frontend/tile_key.cpp
index cd1ff9dc7e..106795ce63 100755
--- a/drape_frontend/tile_key.cpp
+++ b/drape_frontend/tile_key.cpp
@@ -69,7 +69,8 @@ bool TileKey::EqualStrict(TileKey const & other) const
 m2::RectD TileKey::GetGlobalRect(bool clipByDataMaxZoom) const
 {
   int const zoomLevel = clipByDataMaxZoom ? ClipTileZoomByMaxDataZoom(m_zoomLevel) : m_zoomLevel;
-  double const worldSizeDevisor = 1 << zoomLevel;
+  ASSERT_GREATER(zoomLevel, 0, ());
+  double const worldSizeDevisor = 1 << (zoomLevel - 1);
   // Mercator SizeX and SizeY are equal.
   double const rectSize = (MercatorBounds::maxX - MercatorBounds::minX) / worldSizeDevisor;
 
diff --git a/drape_frontend/tile_utils.cpp b/drape_frontend/tile_utils.cpp
index a540ca21d1..45853f459f 100755
--- a/drape_frontend/tile_utils.cpp
+++ b/drape_frontend/tile_utils.cpp
@@ -13,8 +13,9 @@ namespace df
 CoverageResult CalcTilesCoverage(m2::RectD const & rect, int targetZoom,
                                  function<void(int, int)> const & processTile)
 {
+  ASSERT_GREATER(targetZoom, 0, ());
   double const range = MercatorBounds::maxX - MercatorBounds::minX;
-  double const rectSize = range / (1 << targetZoom);
+  double const rectSize = range / (1 << (targetZoom - 1));
 
   CoverageResult result;
   result.m_minTileX = static_cast<int>(floor(rect.minX() / rectSize));
diff --git a/geometry/clipping.cpp b/geometry/clipping.cpp
index 5faa3d215a..d64cd27069 100644
--- a/geometry/clipping.cpp
+++ b/geometry/clipping.cpp
@@ -3,18 +3,9 @@
 
 #include "std/vector.hpp"
 
-#include <boost/geometry.hpp>
-#include <boost/geometry/geometries/linestring.hpp>
-#include <boost/geometry/geometries/point_xy.hpp>
-#include <boost/geometry/geometries/polygon.hpp>
-
 namespace m2
 {
 
-using TPoint = boost::geometry::model::d2::point_xy<double>;
-using TPolygon = boost::geometry::model::polygon<TPoint>;
-using TLine = boost::geometry::model::linestring<TPoint>;
-
 using AddPoligonPoint = function<void(m2::PointD const &)>;
 using InsertCorners = function<void(int, int)>;
 
@@ -61,6 +52,9 @@ void ClipTriangleByRect(m2::RectD const & rect, m2::PointD const & p1,
                         m2::PointD const & p2, m2::PointD const & p3,
                         ClipTriangleByRectResultIt const & resultIterator)
 {
+  if (resultIterator == nullptr)
+    return;
+
   if (rect.IsPointInside(p1) && rect.IsPointInside(p2) && rect.IsPointInside(p3))
   {
     resultIterator(p1, p2, p3);
@@ -141,43 +135,54 @@ vector<m2::SharedSpline> ClipSplineByRect(m2::RectD const & rect, m2::SharedSpli
 {
   vector<m2::SharedSpline> result;
 
+  vector<m2::PointD> const & path = spline->GetPath();
+  if (path.size() < 2)
+    return result;
+
   m2::RectD splineRect;
-  for (m2::PointD const & p : spline->GetPath())
+  for (m2::PointD const & p : path)
     splineRect.Add(p);
 
+  // Check for spline is inside.
   if (rect.IsRectInside(splineRect))
   {
     result.push_back(spline);
     return result;
   }
 
-  m2::PointD const rt = rect.RightTop();
-  m2::PointD const rb = rect.RightBottom();
-  m2::PointD const lt = rect.LeftTop();
-  m2::PointD const lb = rect.LeftBottom();
-  TPolygon rectanglePoly;
-  boost::geometry::assign_points(rectanglePoly,
-                                 vector<TPoint>{ TPoint(lt.x, lt.y), TPoint(rt.x, rt.y),
-                                                 TPoint(rb.x, rb.y), TPoint(lb.x, lb.y),
-                                                 TPoint(lt.x, lt.y) });
-  TLine line;
-  line.reserve(spline->GetSize());
-  for (m2::PointD const & p : spline->GetPath())
-    line.push_back(TPoint(p.x, p.y));
-
-  vector<TLine> output;
-  if (!boost::geometry::intersection(rectanglePoly, line, output) || output.empty())
+  // Check for spline is outside.
+  if (!rect.IsIntersect(splineRect))
     return result;
 
-  for (TLine const & outLine : output)
-  {
-    m2::SharedSpline s;
-    s.Reset(new m2::Spline(outLine.size()));
-    for (TPoint const & p : outLine)
-      s->AddPoint(m2::PointD(p.x(), p.y()));
-    result.push_back(move(s));
-  }
+  // Divide spline into parts.
+  result.reserve(2);
+  m2::PointD p1, p2;
+  int code1 = 0;
+  int code2 = 0;
+  m2::SharedSpline s;
+  s.Reset(new m2::Spline(path.size()));
 
+  for (size_t i = 0; i < path.size() - 1; i++)
+  {
+    p1 = path[i];
+    p2 = path[i + 1];
+    if (m2::Intersect(rect, p1, p2, code1, code2))
+    {
+      if ((p1 - p2).IsAlmostZero())
+        continue;
+
+      if (s.IsNull())
+        s.Reset(new m2::Spline(path.size() - i));
+
+      s->AddPoint(p1);
+      if (code2 != 0 || i + 2 == path.size())
+      {
+        s->AddPoint(p2);
+        result.push_back(s);
+        s.Reset(nullptr);
+      }
+    }
+  }
   return result;
 }
 
diff --git a/geometry/geometry_tests/clipping_test.cpp b/geometry/geometry_tests/clipping_test.cpp
index 212dbc7051..39e456b40e 100644
--- a/geometry/geometry_tests/clipping_test.cpp
+++ b/geometry/geometry_tests/clipping_test.cpp
@@ -246,4 +246,17 @@ UNIT_TEST(Clipping_ClipSplineByRect)
   vector<m2::SharedSpline> result4 = m2::ClipSplineByRect(r, spline4);
   vector<m2::SharedSpline> expectedResult4 = ConstructSplineList({ { m2::PointD(-0.5, 0.0), m2::PointD(0.5, 0.5) } });
   TEST(CompareSplineLists(result4, expectedResult4), ());
+
+  // Intersection. Long spline.
+  m2::SharedSpline spline5;
+  spline5.Reset(new m2::Spline(4));
+  spline5->AddPoint(m2::PointD(-2.0, 0.0));
+  spline5->AddPoint(m2::PointD(0.0, 0.0));
+  spline5->AddPoint(m2::PointD(0.5, 0.5));
+  spline5->AddPoint(m2::PointD(2.0, 1.0));
+  vector<m2::SharedSpline> result5 = m2::ClipSplineByRect(r, spline5);
+  vector<m2::SharedSpline> expectedResult5 = ConstructSplineList({ { m2::PointD(-1.0, 0.0), m2::PointD(0.0, 0.0),
+                                                                     m2::PointD(0.5, 0.5), m2::PointD(1.0, 0.66666666) } });
+  TEST(CompareSplineLists(result5, expectedResult5), ());
 }
+