Big update.

src/strategy/values/IsBehindValue.cpp

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU GPL v2 license, you may redistribute it and/or modify it under version 2 of the License, or (at your option), any later version.
+ */
+
+#include "IsBehindValue.h"
+#include "Playerbots.h"
+
+bool IsBehindValue::Calculate()
+{
+    Unit* target = AI_VALUE(Unit*, qualifier);
+    if (!target)
+        return false;
+
+
+    float targetOrientation = target->GetOrientation();
+    float orientation = bot->GetOrientation();
+    float distance = bot->GetDistance(target);
+
+    return distance <= ATTACK_DISTANCE && abs(targetOrientation - orientation) < M_PI / 2;
+}