From df104b16c62dc05e8d8a28e490919f2d776d8033 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20T=C5=AFma?= <tumic@cbox.cz>
Date: Thu, 13 Sep 2018 01:45:17 +0200
Subject: [PATCH] Yet another optimization

---
 src/common/greatcircle.cpp | 32 ++++++++++++++++++++------------
 src/common/greatcircle.h   |  4 ++--
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/src/common/greatcircle.cpp b/src/common/greatcircle.cpp
index 607dc23d..7192bf0c 100644
--- a/src/common/greatcircle.cpp
+++ b/src/common/greatcircle.cpp
@@ -2,25 +2,33 @@
 
 GreatCircle::GreatCircle(const Coordinates &c1, const Coordinates &c2)
 {
-	_lat1 = deg2rad(c1.lat());
-	_lon1 = deg2rad(c1.lon());
-	_lat2 = deg2rad(c2.lat());
-	_lon2 = deg2rad(c2.lon());
+	double lat1 = deg2rad(c1.lat());
+	double lon1 = deg2rad(c1.lon());
+	double lat2 = deg2rad(c2.lat());
+	double lon2 = deg2rad(c2.lon());
 
-	_cosLat1 = cos(_lat1);
-	_cosLat2 = cos(_lat2);
-	_d = 2 * asin(sqrt(pow((sin((_lat1 - _lat2) / 2)), 2) + _cosLat1
-	  * _cosLat2 * pow(sin((_lon1 - _lon2) / 2), 2)));
+	double cosLat1 = cos(lat1);
+	double cosLat2 = cos(lat2);
+	_sinLat1 = sin(lat1);
+	_sinLat2 = sin(lat2);
+
+	_xA = cosLat1 * cos(lon1);
+	_xB = cosLat2 * cos(lon2);
+	_yA = cosLat1 * sin(lon1);
+	_yB = cosLat2 * sin(lon2);
+
+	_d = 2 * asin(sqrt(pow((sin((lat1 - lat2) / 2)), 2) + cosLat1 * cosLat2
+	  * pow(sin((lon1 - lon2) / 2), 2)));
 	_sinD = sin(_d);
 }
 
 Coordinates GreatCircle::pointAt(double f) const
 {
 	double A = sin((1.0 - f) * _d) / _sinD;
-	double B = sin(f*_d) / _sinD;
-	double x = A * _cosLat1 * cos(_lon1) + B * _cosLat2 * cos(_lon2);
-	double y = A * _cosLat1 * sin(_lon1) + B * _cosLat2 * sin(_lon2);
-	double z = A * sin(_lat1) + B * sin(_lat2);
+	double B = sin(f * _d) / _sinD;
+	double x = A * _xA + B * _xB;
+	double y = A * _yA + B * _yB;
+	double z = A * _sinLat1 + B * _sinLat2;
 
 	return Coordinates(rad2deg(atan2(y, x)), rad2deg(atan2(z, sqrt(x*x + y*y))));
 }
diff --git a/src/common/greatcircle.h b/src/common/greatcircle.h
index 5ed1db98..f67f8433 100644
--- a/src/common/greatcircle.h
+++ b/src/common/greatcircle.h
@@ -11,10 +11,10 @@ public:
 	Coordinates pointAt(double f) const;
 
 private:
-	double _lat1, _lon1, _lat2, _lon2;
-	double _cosLat1, _cosLat2;
+	double _xA, _xB, _yA, _yB;
 	double _d;
 	double _sinD;
+	double _sinLat1, _sinLat2;
 };
 
 #endif // GREATCIRCLE_H