From ae8ddd04d90029c4c6cc1942f362d91e0890e2a8 Mon Sep 17 00:00:00 2001
From: Christian Schmitt <chris@ilovelinux.de>
Date: Wed, 5 Feb 2014 17:43:07 +0100
Subject: [PATCH] [AIModel] Fix a crash when starting at the poles and reduce
 property reading

---
 src/AIModel/AIAircraft.cxx | 12 +++---------
 src/AIModel/AIAircraft.hxx |  1 -
 src/AIModel/AIManager.cxx  |  8 ++++++++
 src/AIModel/AIManager.hxx  |  2 ++
 4 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/AIModel/AIAircraft.cxx b/src/AIModel/AIAircraft.cxx
index f05a58917..5e803ef5e 100644
--- a/src/AIModel/AIAircraft.cxx
+++ b/src/AIModel/AIAircraft.cxx
@@ -172,18 +172,12 @@ void FGAIAircraft::setPerformance(const std::string& acType, const std::string&
     // AI manager. In this particular case, the AIAircraft is used to shadow the user's aircraft's behavior in the AI world.
     // Since we perhaps don't want a radar entry of our own aircraft, the following conditional should probably be adequate
     // enough
-     if (manager)
+     if (manager){
         UpdateRadar(manager);
-     checkVisibility();
+	invisible = !manager->isVisible(pos);
+     }
   }
 
-void FGAIAircraft::checkVisibility() 
-{
-  double visibility_meters = fgGetDouble("/environment/visibility-m");
-  invisible = (SGGeodesy::distanceM(globals->get_view_position(), pos) > visibility_meters);
-}
-
-
 
 void FGAIAircraft::AccelTo(double speed) {
     tgt_speed = speed;
diff --git a/src/AIModel/AIAircraft.hxx b/src/AIModel/AIAircraft.hxx
index 0d92868ee..3ad8b8a67 100644
--- a/src/AIModel/AIAircraft.hxx
+++ b/src/AIModel/AIAircraft.hxx
@@ -155,7 +155,6 @@ private:
     void updateActualState();
     void updateModelProperties(double dt);
     void handleATCRequests();
-    void checkVisibility();
     inline bool isStationary() { return ((fabs(speed)<=0.0001)&&(fabs(tgt_speed)<=0.0001));}
     inline bool needGroundElevation() { if (!isStationary()) _needsGroundElevation=true;return _needsGroundElevation;}
    
diff --git a/src/AIModel/AIManager.cxx b/src/AIModel/AIManager.cxx
index aa80b26c5..27582d9ca 100644
--- a/src/AIModel/AIManager.cxx
+++ b/src/AIModel/AIManager.cxx
@@ -134,6 +134,7 @@ FGAIManager::init() {
     
     globals->get_commands()->addCommand("load-scenario", this, &FGAIManager::loadScenarioCommand);
     globals->get_commands()->addCommand("unload-scenario", this, &FGAIManager::unloadScenarioCommand);
+    _environmentVisiblity = fgGetNode("/environment/visibility-m");
 }
 
 void
@@ -184,6 +185,7 @@ FGAIManager::shutdown()
     }
     
     ai_list.clear();
+    _environmentVisiblity.clear();
     
     globals->get_commands()->removeCommand("load-scenario");
     globals->get_commands()->removeCommand("unload-scenario");
@@ -298,6 +300,12 @@ FGAIManager::attach(FGAIBase *model)
     p->setBoolValue("valid", true);
 }
 
+bool FGAIManager::isVisible(const SGGeod& pos) const
+{
+  double visibility_meters = _environmentVisiblity->getDoubleValue();
+  return ( dist(globals->get_view_position_cart(), SGVec3d::fromGeod(pos)) ) <= visibility_meters;
+}
+
 int
 FGAIManager::getNumAiObjects() const
 {
diff --git a/src/AIModel/AIManager.hxx b/src/AIModel/AIManager.hxx
index 140b34366..a35f64968 100644
--- a/src/AIModel/AIManager.hxx
+++ b/src/AIModel/AIManager.hxx
@@ -77,6 +77,7 @@ public:
         SGGeod& geodPos, double& hdng, SGVec3d& uvw);
 
     FGAIBasePtr addObject(const SGPropertyNode* definition);
+    bool isVisible(const SGGeod& pos) const;
     
     /**
      * @brief given a reference to an /ai/models/<foo>[n] node, return the
@@ -117,6 +118,7 @@ private:
     SGPropertyNode_ptr user_speed_node;
     SGPropertyNode_ptr wind_from_east_node;
     SGPropertyNode_ptr wind_from_north_node;
+    SGPropertyNode_ptr _environmentVisiblity;
 
 
     ai_list_type ai_list;