aicombat pathfinding workaround

apps/openmw/mwmechanics/aicombat.cpp

@@ -240,16 +240,20 @@ namespace MWMechanics
             //target is at far distance: build path to target OR follow target (if previously actor had reached it once)
             mFollowTarget = false;
 
-            buildNewPath(actor);
+            buildNewPath(actor); //not guaranteed, check before use
 
             //delete visited path node
             mPathFinder.checkPathCompleted(pos.pos[0],pos.pos[1],pos.pos[2]);
 
-            //try shortcut
-            if(vDir.length() < mPathFinder.getDistToNext(pos.pos[0],pos.pos[1],pos.pos[2]) && MWBase::Environment::get().getWorld()->getLOS(actor, mTarget)) 
-                mTargetAngle = Ogre::Radian( Ogre::Math::ACos(vDir.y / vDir.length()) * sgn(Ogre::Math::ASin(vDir.x / vDir.length())) ).valueDegrees();
-            else
-                mTargetAngle = mPathFinder.getZAngleToNext(pos.pos[0], pos.pos[1]);
+            //if buildNewPath() failed leave mTargetAngle unchanged
+            if(!mPathFinder.getPath().empty())
+            {
+                //try shortcut
+                if(vDir.length() < mPathFinder.getDistToNext(pos.pos[0],pos.pos[1],pos.pos[2]) && MWBase::Environment::get().getWorld()->getLOS(actor, mTarget)) 
+                    mTargetAngle = Ogre::Radian( Ogre::Math::ACos(vDir.y / vDir.length()) * sgn(Ogre::Math::ASin(vDir.x / vDir.length())) ).valueDegrees();
+                else
+                    mTargetAngle = mPathFinder.getZAngleToNext(pos.pos[0], pos.pos[1]);
+            }
             mRotate = true;
             
             mMovement.mPosition[1] = 1;
@@ -300,9 +304,13 @@ namespace MWMechanics
         dest.mZ = mTarget.getRefData().getPosition().pos[2];
         Ogre::Vector3 newPathTarget = Ogre::Vector3(dest.mX, dest.mY, dest.mZ);
 
-        ESM::Pathgrid::Point lastPt = mPathFinder.getPath().back();
-        Ogre::Vector3 currPathTarget(lastPt.mX, lastPt.mY, lastPt.mZ);
-        float dist = Ogre::Math::Abs((newPathTarget - currPathTarget).length());
+        float dist = -1; //hack to indicate first time, to construct a new path
+        if(!mPathFinder.getPath().empty())
+        {
+            ESM::Pathgrid::Point lastPt = mPathFinder.getPath().back();
+            Ogre::Vector3 currPathTarget(lastPt.mX, lastPt.mY, lastPt.mZ);
+            dist = Ogre::Math::Abs((newPathTarget - currPathTarget).length());
+        }
 
         float targetPosThreshold;
         bool isOutside = actor.getCell()->mCell->isExterior();
@@ -311,7 +319,7 @@ namespace MWMechanics
         else
             targetPosThreshold = 100;
 
-        if(dist > targetPosThreshold)   
+        if((dist < 0) || (dist > targetPosThreshold))
         {
             //construct new path only if target has moved away more than on <targetPosThreshold>
             ESM::Position pos = actor.getRefData().getPosition();
@@ -332,8 +340,11 @@ namespace MWMechanics
                 //maybe here is a mistake (?): PathFinder::getPathSize() returns number of grid points in the path,
                 //not the actual path length. Here we should know if the new path is actually more effective.
                 //if(pathFinder2.getPathSize() < mPathFinder.getPathSize())
-                newPathFinder.syncStart(mPathFinder.getPath());
-                mPathFinder = newPathFinder;
+                if(!mPathFinder.getPath().empty())
+                {
+                    newPathFinder.syncStart(mPathFinder.getPath());
+                    mPathFinder = newPathFinder;
+                }
             }
         }
     }

apps/openmw/mwmechanics/pathfinding.cpp

@@ -391,6 +391,8 @@ namespace MWMechanics
 
     void PathFinder::syncStart(const std::list<ESM::Pathgrid::Point> &path)
     {
+        if (path.size() < 2)
+            return; //nothing to pop
         std::list<ESM::Pathgrid::Point>::const_iterator oldStart = path.begin();
         std::list<ESM::Pathgrid::Point>::iterator iter = ++mPath.begin();