From 2ac8539d73b9502c5ca05b85f2a05c019f393a84 Mon Sep 17 00:00:00 2001
From: Daria Volvenkova <d.volvenkova@corp.mail.ru>
Date: Thu, 9 Jun 2016 16:30:39 +0300
Subject: [PATCH] Calculate current rotation angle in perspective mode.

---
 drape_frontend/frontend_renderer.cpp |  6 ++++-
 drape_frontend/navigator.cpp         |  4 ++--
 drape_frontend/rule_drawer.cpp       |  4 ++--
 geometry/screenbase.cpp              | 35 ++++++++++++++++++++--------
 geometry/screenbase.hpp              |  2 +-
 5 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/drape_frontend/frontend_renderer.cpp b/drape_frontend/frontend_renderer.cpp
index 3b06a0adbf..9b826a08c7 100755
--- a/drape_frontend/frontend_renderer.cpp
+++ b/drape_frontend/frontend_renderer.cpp
@@ -1232,7 +1232,11 @@ void FrontendRenderer::RefreshModelView(ScreenBase const & screen)
 
   m_generalUniforms.SetMatrix4x4Value("modelView", mv.m_data);
 
-  float const zScale = 2.0f / (screen.GetHeight() * screen.GetScale());
+  // TODO: Calculate exact value of zScale
+  double const averageScale3d = 3.0;
+  float const zScale = 2.0f / (screen.PixelRectIn3d().SizeY() * averageScale3d * screen.GetScale());
+  //float const zScale = 2.0f / (screen.GetHeight() * screen.GetScale());
+
   m_generalUniforms.SetFloatValue("zScale", zScale);
 }
 
diff --git a/drape_frontend/navigator.cpp b/drape_frontend/navigator.cpp
index b68c595e37..a2e2034ec1 100644
--- a/drape_frontend/navigator.cpp
+++ b/drape_frontend/navigator.cpp
@@ -309,9 +309,9 @@ void Navigator::Disable3dMode()
 
 bool Navigator::UpdatePerspective()
 {
-  bool const isPerspective = m_Screen.isPerspective();
+  double const maxPerspAngle = m_Screen.GetMaxRotationAngle();
   m_Screen.UpdatePerspectiveParameters();
-  return isPerspective != m_Screen.isPerspective();
+  return maxPerspAngle != m_Screen.GetMaxRotationAngle();
 }
 
 m2::AnyRectD ToRotated(Navigator const & navigator, m2::RectD const & rect)
diff --git a/drape_frontend/rule_drawer.cpp b/drape_frontend/rule_drawer.cpp
index a3b2ba949a..2a7a3a8102 100644
--- a/drape_frontend/rule_drawer.cpp
+++ b/drape_frontend/rule_drawer.cpp
@@ -203,10 +203,10 @@ void RuleDrawer::operator()(FeatureType const & f)
       double const lat = MercatorBounds::YToLat(featureCenter.y);
 
       m2::RectD rectMercator = MercatorBounds::MetresToXY(lon, lat, heightInMeters);
-      areaHeight = m2::PointD(rectMercator.SizeX(), rectMercator.SizeY()).Length();
+      areaHeight = (rectMercator.SizeX() + rectMercator.SizeY()) / 2.0;
 
       rectMercator = MercatorBounds::MetresToXY(lon, lat, minHeigthInMeters);
-      areaMinHeight = m2::PointD(rectMercator.SizeX(), rectMercator.SizeY()).Length();
+      areaMinHeight = (rectMercator.SizeX() + rectMercator.SizeY()) / 2.0;
     }
 
     bool applyPointStyle = s.PointStyleExists();
diff --git a/geometry/screenbase.cpp b/geometry/screenbase.cpp
index fd5ce38f9b..7dc94b4efd 100644
--- a/geometry/screenbase.cpp
+++ b/geometry/screenbase.cpp
@@ -7,6 +7,13 @@
 
 #include "std/cmath.hpp"
 
+double constexpr kPerspectiveAngleFOV = math::pi / 3.0;
+double constexpr kMaxPerspectiveAngle1 = math::pi4;
+double constexpr kMaxPerspectiveAngle2 = math::pi * 55.0 / 180.0;
+
+double constexpr kStartPerspectiveScale1 = 1.7e-5;
+double constexpr kEndPerspectiveScale1 = 0.3e-5;
+double constexpr kEndPerspectiveScale2 = 0.13e-5;
 
 ScreenBase::ScreenBase() :
     m_PixelRect(0, 0, 640, 480),
@@ -26,7 +33,6 @@ ScreenBase::ScreenBase() :
 {
   m_GtoP = math::Identity<double, 3>();
   m_PtoG = math::Identity<double, 3>();
-//  UpdateDependentParameters();
 }
 
 ScreenBase::ScreenBase(m2::RectI const & pxRect, m2::AnyRectD const & glbRect)
@@ -77,13 +83,20 @@ void ScreenBase::UpdateDependentParameters()
 
 double ScreenBase::CalculatePerspectiveAngle(double scale)
 {
-  double const kStartPerspectiveScale = 0.13e-4;
-  double const kMaxScale = 0.13e-5;
-  double const kMaxPerspectiveAngle = math::pi4;
-
-  if (scale > kStartPerspectiveScale)
+  if (scale > kStartPerspectiveScale1)
     return 0.0;
-  return kMaxPerspectiveAngle * (kStartPerspectiveScale - scale) / (kStartPerspectiveScale - kMaxScale);
+  else if (scale > kEndPerspectiveScale1)
+  {
+    double const k = (kStartPerspectiveScale1 - scale) / (kStartPerspectiveScale1 - kEndPerspectiveScale1);
+    return kMaxPerspectiveAngle1 * k;
+  }
+  else if (scale > kEndPerspectiveScale2)
+  {
+    double const k = (kEndPerspectiveScale1 - scale) / (kEndPerspectiveScale1 - kEndPerspectiveScale2);
+    return kMaxPerspectiveAngle1 + (kMaxPerspectiveAngle2 - kMaxPerspectiveAngle1) * k;
+  }
+  else
+    return kMaxPerspectiveAngle2 * 0.99;
 }
 
 void ScreenBase::UpdatePerspectiveParameters()
@@ -91,10 +104,12 @@ void ScreenBase::UpdatePerspectiveParameters()
   double const angle = CalculatePerspectiveAngle(m_Scale);
   if (angle > 0.0)
   {
-    if (m_isPerspective)
-      SetRotationAngle(angle);
+    if (!m_isPerspective || (angle < kMaxPerspectiveAngle1 && m_3dMaxAngleX > kMaxPerspectiveAngle1))
+      ApplyPerspective(angle, kMaxPerspectiveAngle1, kPerspectiveAngleFOV);
+    else if (angle > m_3dMaxAngleX)
+      ApplyPerspective(angle, kMaxPerspectiveAngle2, kPerspectiveAngleFOV);
     else
-      ApplyPerspective(angle, math::pi4, math::pi / 3);
+      SetRotationAngle(angle);
   }
   else if (m_isPerspective)
     ResetPerspective();
diff --git a/geometry/screenbase.hpp b/geometry/screenbase.hpp
index ef5125d9e4..24b4076643 100644
--- a/geometry/screenbase.hpp
+++ b/geometry/screenbase.hpp
@@ -132,7 +132,7 @@ public:
 
   void SetRotationAngle(double rotationAngle);
   double GetRotationAngle() const { return m_3dAngleX; }
-
+  double GetMaxRotationAngle() const { return m_3dMaxAngleX; }
   double GetAngleFOV() const { return m_3dFOV; }
 
   m2::PointD P3dtoP(m2::PointD const & pt) const;