Check for obstacle before back up (bug #4656)

CHANGELOG.md

@@ -134,6 +134,7 @@
     Bug #4649: Levelup fully restores health
     Bug #4653: Length of non-ASCII strings is handled incorrectly in ESM reader
     Bug #4654: Editor: UpdateVisitor does not initialize skeletons for animated objects
+    Bug #4656: Combat AI: back up behaviour is incorrect
     Bug #4668: Editor: Light source color is displayed as an integer
     Bug #4669: ToggleCollision should trace the player down after collision being enabled
     Bug #4671: knownEffect functions should use modified Alchemy skill

apps/openmw/mwbase/world.hpp

@@ -297,9 +297,11 @@ namespace MWBase
             ///< Queues movement for \a ptr (in local space), to be applied in the next call to
             /// doPhysics.
 
-            virtual bool castRay (float x1, float y1, float z1, float x2, float y2, float z2, bool ignoreDoors=false) = 0;
+            virtual bool castRay (float x1, float y1, float z1, float x2, float y2, float z2, int mask) = 0;
             ///< cast a Ray and return true if there is an object in the ray path.
 
+            virtual bool castRay (float x1, float y1, float z1, float x2, float y2, float z2) = 0;
+
             virtual bool toggleCollisionMode() = 0;
             ///< Toggle collision mode for player. If disabled player object should ignore
             /// collisions and gravity.

apps/openmw/mwmechanics/aicombat.cpp

@@ -4,6 +4,10 @@
 
 #include <components/esm/aisequence.hpp>
 
+#include <components/sceneutil/positionattitudetransform.hpp>
+
+#include "../mwphysics/collisiontype.hpp"
+
 #include "../mwworld/class.hpp"
 #include "../mwworld/esmstore.hpp"
 
@@ -456,7 +460,48 @@ namespace MWMechanics
             mTimerCombatMove = 0.1f + 0.1f * Misc::Rng::rollClosedProbability();
             mCombatMove = true;
         }
+        else if (isDistantCombat)
+        {
+            // Backing up behaviour
+            // Actor backs up slightly further away than opponent's weapon range
+            // (in vanilla - only as far as oponent's weapon range),
+            // or not at all if opponent is using a ranged weapon
+
+            if (targetUsesRanged || distToTarget > rangeAttackOfTarget*1.5) // Don't back up if the target is wielding ranged weapon
+                return;
+
+            // actor should not back up into water
+            if (MWBase::Environment::get().getWorld()->isUnderwater(MWWorld::ConstPtr(actor), 0.5f))
+                return;
+
+            int mask = MWPhysics::CollisionType_World | MWPhysics::CollisionType_HeightMap | MWPhysics::CollisionType_Door;
+
+            // Actor can not back up if there is no free space behind
+            // Currently we take the 35% of actor's height from the ground as vector height.
+            // This approach allows us to detect small obstacles (e.g. crates) and curved walls.
+            osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getHalfExtents(actor);
+            osg::Vec3f pos = actor.getRefData().getPosition().asVec3();
+            osg::Vec3f source = pos + osg::Vec3f(0, 0, 0.75f * halfExtents.z());
+            osg::Vec3f fallbackDirection = actor.getRefData().getBaseNode()->getAttitude() * osg::Vec3f(0,-1,0);
+            osg::Vec3f destination = source + fallbackDirection * (halfExtents.y() + 16);
+
+            bool isObstacleDetected = MWBase::Environment::get().getWorld()->castRay(source.x(), source.y(), source.z(), destination.x(), destination.y(), destination.z(), mask);
+            if (isObstacleDetected)
+                return;
+
+            // Check if there is nothing behind - probably actor is near cliff.
+            // A current approach: cast ray 1.5-yard ray down in 1.5 yard behind actor from 35% of actor's height.
+            // If we did not hit anything, there is a cliff behind actor.
+            source = pos + osg::Vec3f(0, 0, 0.75f * halfExtents.z()) + fallbackDirection * (halfExtents.y() + 96);
+            destination = source - osg::Vec3f(0, 0, 0.75f * halfExtents.z() + 96);
+            bool isCliffDetected = !MWBase::Environment::get().getWorld()->castRay(source.x(), source.y(), source.z(), destination.x(), destination.y(), destination.z(), mask);
+            if (isCliffDetected)
+                return;
+
+            mMovement.mPosition[1] = -1;
+        }
         // dodge movements (for NPCs and bipedal creatures)
+        // Note: do not use for ranged combat yet since in couple with back up behaviour can move actor out of cliff
         else if (actor.getClass().isBipedal(actor))
         {
             // apply sideway movement (kind of dodging) with some probability
@@ -468,20 +513,6 @@ namespace MWMechanics
                 mCombatMove = true;
             }
         }
-
-        // Backing up behaviour
-        // Actor backs up slightly further away than opponent's weapon range
-        // (in vanilla - only as far as oponent's weapon range),
-        // or not at all if opponent is using a ranged weapon
-        if (isDistantCombat)
-        {
-            // actor should not back up into water
-            if (MWBase::Environment::get().getWorld()->isUnderwater(MWWorld::ConstPtr(actor), 0.5f))
-                return;
-
-            if (!targetUsesRanged && distToTarget <= rangeAttackOfTarget*1.5) // Don't back up if the target is wielding ranged weapon
-                mMovement.mPosition[1] = -1;
-        }
     }
 
     void AiCombatStorage::updateCombatMove(float duration)

apps/openmw/mwmechanics/pathfinding.cpp

@@ -5,6 +5,8 @@
 #include "../mwbase/world.hpp"
 #include "../mwbase/environment.hpp"
 
+#include "../mwphysics/collisiontype.hpp"
+
 #include "../mwworld/cellstore.hpp"
 
 #include "pathgrid.hpp"
@@ -246,8 +248,9 @@ namespace MWMechanics
                     converter.toWorld(temp);
                     // Add Z offset since path node can overlap with other objects.
                     // Also ignore doors in raytesting.
+                    int mask = MWPhysics::CollisionType_World;
                     bool isPathClear = !MWBase::Environment::get().getWorld()->castRay(
-                        startPoint.mX, startPoint.mY, startPoint.mZ+16, temp.mX, temp.mY, temp.mZ+16, true);
+                        startPoint.mX, startPoint.mY, startPoint.mZ+16, temp.mX, temp.mY, temp.mZ+16, mask);
                     if (isPathClear)
                         mPath.pop_front();
                 }

apps/openmw/mwworld/worldimp.cpp

@@ -1505,15 +1505,18 @@ namespace MWWorld
             moveObjectImp(player->first, player->second.x(), player->second.y(), player->second.z(), false);
     }
 
-    bool World::castRay (float x1, float y1, float z1, float x2, float y2, float z2, bool ignoreDoors)
+    bool World::castRay (float x1, float y1, float z1, float x2, float y2, float z2)
+    {
+        int mask = MWPhysics::CollisionType_World | MWPhysics::CollisionType_Door;
+        bool result = castRay(x1, y1, z1, x2, y2, z2, mask);
+        return result;
+    }
+
+    bool World::castRay (float x1, float y1, float z1, float x2, float y2, float z2, int mask)
     {
         osg::Vec3f a(x1,y1,z1);
         osg::Vec3f b(x2,y2,z2);
 
-        int mask = MWPhysics::CollisionType_World;
-        if (!ignoreDoors)
-            mask |= MWPhysics::CollisionType_Door;
-
         MWPhysics::PhysicsSystem::RayResult result = mPhysics->castRay(a, b, MWWorld::Ptr(), std::vector<MWWorld::Ptr>(), mask);
         return result.mHit;
     }

apps/openmw/mwworld/worldimp.hpp

@@ -402,9 +402,11 @@ namespace MWWorld
             ///< Queues movement for \a ptr (in local space), to be applied in the next call to
             /// doPhysics.
 
-            bool castRay (float x1, float y1, float z1, float x2, float y2, float z2, bool ignoreDoors=false) override;
+            bool castRay (float x1, float y1, float z1, float x2, float y2, float z2, int mask) override;
             ///< cast a Ray and return true if there is an object in the ray path.
 
+            bool castRay (float x1, float y1, float z1, float x2, float y2, float z2) override;
+
             bool toggleCollisionMode() override;
             ///< Toggle collision mode for player. If disabled player object should ignore
             /// collisions and gravity.