From 5da341d1fc14d4c007ddd1bdf37f7bddf29f25c2 Mon Sep 17 00:00:00 2001
From: jean-pierre charras <jp.charras@wanadoo.fr>
Date: Tue, 26 Apr 2016 14:14:26 +0200
Subject: [PATCH] Optimize VECTOR2::Rotation for 0, 90, 180 and -90 degrees by
 avoiding time consumming calculations.

---
 include/math/vector2d.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/math/vector2d.h b/include/math/vector2d.h
index 764534add9..b9ca1d22ce 100644
--- a/include/math/vector2d.h
+++ b/include/math/vector2d.h
@@ -358,6 +358,19 @@ VECTOR2<T>& VECTOR2<T>::operator-=( const T& aScalar )
 template <class T>
 VECTOR2<T> VECTOR2<T>::Rotate( double aAngle ) const
 {
+    // fast calculation of some rotations, very frequently found
+    if( aAngle == 0.0 )
+        return VECTOR2<T> ( T( x ), T( y ) );
+
+    if( aAngle == 90.0 )
+        return VECTOR2<T> ( T( -y ), T( x ) );
+
+    if( aAngle == -90.0 )
+        return VECTOR2<T> ( T( y ), T( -x ) );
+
+    if( aAngle == 180.0 || aAngle == -180.0 )
+        return VECTOR2<T> ( T( -x ), T( -y ) );
+
     double  sa  = sin( aAngle );
     double  ca  = cos( aAngle );