Consider path not found when there is navmesh query error

Fix a specific case when the guard at the start of the game fails to find path
due to failed getPolyHeight call that results into a partial path to the
target.

apps/openmw/mwmechanics/pathfinding.cpp

@@ -369,7 +369,13 @@ namespace MWMechanics
         mPath.clear();
 
         // If it's not possible to build path over navmesh due to disabled navmesh generation fallback to straight path
-        if (!buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents, flags, areaCosts, std::back_inserter(mPath)))
+        DetourNavigator::Status status = buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents, flags,
+                                                                  areaCosts, std::back_inserter(mPath));
+
+        if (status != DetourNavigator::Status::Success)
+            mPath.clear();
+
+        if (status == DetourNavigator::Status::NavMeshNotFound)
             mPath.push_back(endPoint);
 
         mConstructed = !mPath.empty();
@@ -382,25 +388,33 @@ namespace MWMechanics
         mPath.clear();
         mCell = cell;
 
-        bool hasNavMesh = false;
+        DetourNavigator::Status status = DetourNavigator::Status::NavMeshNotFound;
 
         if (!actor.getClass().isPureWaterCreature(actor) && !actor.getClass().isPureFlyingCreature(actor))
-            hasNavMesh = buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents, flags, areaCosts, std::back_inserter(mPath));
+        {
+            status = buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents, flags, areaCosts, std::back_inserter(mPath));
+            if (status != DetourNavigator::Status::Success)
+                mPath.clear();
+        }
 
-        if (hasNavMesh && mPath.empty())
-            buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents,
+        if (status != DetourNavigator::Status::NavMeshNotFound && mPath.empty())
+        {
+            status = buildPathByNavigatorImpl(actor, startPoint, endPoint, halfExtents,
                                      flags | DetourNavigator::Flag_usePathgrid, areaCosts, std::back_inserter(mPath));
+            if (status != DetourNavigator::Status::Success)
+                mPath.clear();
+        }
 
         if (mPath.empty())
             buildPathByPathgridImpl(startPoint, endPoint, pathgridGraph, std::back_inserter(mPath));
 
-        if (!hasNavMesh && mPath.empty())
+        if (status == DetourNavigator::Status::NavMeshNotFound && mPath.empty())
             mPath.push_back(endPoint);
 
         mConstructed = !mPath.empty();
     }
 
-    bool PathFinder::buildPathByNavigatorImpl(const MWWorld::ConstPtr& actor, const osg::Vec3f& startPoint,
+    DetourNavigator::Status PathFinder::buildPathByNavigatorImpl(const MWWorld::ConstPtr& actor, const osg::Vec3f& startPoint,
         const osg::Vec3f& endPoint, const osg::Vec3f& halfExtents, const DetourNavigator::Flags flags,
         const DetourNavigator::AreaCosts& areaCosts, std::back_insert_iterator<std::deque<osg::Vec3f>> out)
     {
@@ -409,9 +423,6 @@ namespace MWMechanics
         const auto navigator = world->getNavigator();
         const auto status = navigator->findPath(halfExtents, stepSize, startPoint, endPoint, flags, areaCosts, out);
 
-        if (status == DetourNavigator::Status::NavMeshNotFound)
-            return false;
-
         if (status != DetourNavigator::Status::Success)
         {
             Log(Debug::Debug) << "Build path by navigator error: \"" << DetourNavigator::getMessage(status)
@@ -420,7 +431,7 @@ namespace MWMechanics
                 << DetourNavigator::WriteFlags {flags} << ")";
         }
 
-        return true;
+        return status;
     }
 
     void PathFinder::buildPathByNavMeshToNextPoint(const MWWorld::ConstPtr& actor, const osg::Vec3f& halfExtents,

apps/openmw/mwmechanics/pathfinding.hpp

@@ -7,6 +7,7 @@
 
 #include <components/detournavigator/flags.hpp>
 #include <components/detournavigator/areatype.hpp>
+#include <components/detournavigator/status.hpp>
 #include <components/esm/defs.hpp>
 #include <components/esm/loadpgrd.hpp>
 
@@ -209,9 +210,10 @@ namespace MWMechanics
             void buildPathByPathgridImpl(const osg::Vec3f& startPoint, const osg::Vec3f& endPoint,
                 const PathgridGraph& pathgridGraph, std::back_insert_iterator<std::deque<osg::Vec3f>> out);
 
-            bool buildPathByNavigatorImpl(const MWWorld::ConstPtr& actor, const osg::Vec3f& startPoint,
-                const osg::Vec3f& endPoint, const osg::Vec3f& halfExtents, const DetourNavigator::Flags flags,
-                const DetourNavigator::AreaCosts& areaCosts, std::back_insert_iterator<std::deque<osg::Vec3f>> out);
+            [[nodiscard]] DetourNavigator::Status buildPathByNavigatorImpl(const MWWorld::ConstPtr& actor,
+                const osg::Vec3f& startPoint, const osg::Vec3f& endPoint, const osg::Vec3f& halfExtents,
+                const DetourNavigator::Flags flags, const DetourNavigator::AreaCosts& areaCosts,
+                std::back_insert_iterator<std::deque<osg::Vec3f>> out);
     };
 }