From 40265bf1181167d927f3870b9d5127e310ce49f7 Mon Sep 17 00:00:00 2001
From: wareya <wareya@gmail.com>
Date: Sat, 20 Mar 2021 21:14:56 -0400
Subject: [PATCH] make unstucking slightly smarter (can turn itself off, also
 acts like flat ground)

---
 apps/openmw/mwphysics/actor.hpp          | 21 +++++++++++++++++++
 apps/openmw/mwphysics/movementsolver.cpp | 26 +++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/apps/openmw/mwphysics/actor.hpp b/apps/openmw/mwphysics/actor.hpp
index 031125f40d..472a79bff5 100644
--- a/apps/openmw/mwphysics/actor.hpp
+++ b/apps/openmw/mwphysics/actor.hpp
@@ -159,6 +159,24 @@ namespace MWPhysics
         MWWorld::Ptr getStandingOnPtr() const;
         void setStandingOnPtr(const MWWorld::Ptr& ptr);
 
+        unsigned int getStuckFrames() const
+        {
+            return mStuckFrames;
+        }
+        void setStuckFrames(unsigned int frames)
+        {
+            mStuckFrames = frames;
+        }
+
+        const osg::Vec3f &getLastStuckPosition() const
+        {
+            return mLastStuckPosition;
+        }
+        void setLastStuckPosition(osg::Vec3f position)
+        {
+            mLastStuckPosition = position;
+        }
+
     private:
         MWWorld::Ptr mStandingOnPtr;
         /// Removes then re-adds the collision object to the dynamics world
@@ -192,6 +210,9 @@ namespace MWPhysics
         btTransform mLocalTransform;
         mutable std::mutex mPositionMutex;
 
+        unsigned int mStuckFrames;
+        osg::Vec3f mLastStuckPosition;
+
         osg::Vec3f mForce;
         std::atomic<bool> mOnGround;
         std::atomic<bool> mOnSlope;
diff --git a/apps/openmw/mwphysics/movementsolver.cpp b/apps/openmw/mwphysics/movementsolver.cpp
index 5f0322a1f2..a393ec5784 100644
--- a/apps/openmw/mwphysics/movementsolver.cpp
+++ b/apps/openmw/mwphysics/movementsolver.cpp
@@ -204,7 +204,7 @@ namespace MWPhysics
         osg::Vec3f lastSlideNormalFallback(0,0,1);
         bool forceGroundTest = false;
 
-        for (int iterations = 0; iterations < sMaxIterations && remainingTime > 0.01f; ++iterations)
+        for (int iterations = 0; iterations < sMaxIterations && remainingTime > 0.0001f; ++iterations)
         {
             osg::Vec3f nextpos = newPosition + velocity * remainingTime;
 
@@ -394,6 +394,12 @@ namespace MWPhysics
                     isOnGround = false;
                 }
             }
+            // forcibly treat stuck actors as if they're on flat ground because buggy collisions when inside of things can/will break ground detection
+            if(physicActor->getStuckFrames() > 0)
+            {
+                isOnGround = true;
+                isOnSlope = false;
+            }
         }
 
         if((isOnGround && !isOnSlope) || newPosition.z() < swimlevel || actor.mFlying)
@@ -437,6 +443,17 @@ namespace MWPhysics
         auto* collisionObject = physicActor->getCollisionObject();
         auto tempPosition = actor.mPosition;
 
+        if(physicActor->getStuckFrames() >= 10)
+        {
+            if((physicActor->getLastStuckPosition() - actor.mPosition).length2() < 100)
+                return;
+            else
+            {
+                physicActor->setStuckFrames(0);
+                physicActor->setLastStuckPosition({0, 0, 0});
+            }
+        }
+
         // use vanilla-accurate collision hull position hack (do same hitbox offset hack as movement solver)
         // if vanilla compatibility didn't matter, the "correct" collision hull position would be physicActor->getScaledMeshTranslation()
         const auto verticalHalfExtent = osg::Vec3f(0.0, 0.0, physicActor->getHalfExtents().z());
@@ -470,6 +487,8 @@ namespace MWPhysics
         auto contactCallback = gatherContacts({0.0, 0.0, 0.0});
         if(contactCallback.mDistance < -sAllowedPenetration)
         {
+            physicActor->setStuckFrames(physicActor->getStuckFrames() + 1);
+            physicActor->setLastStuckPosition(actor.mPosition);
             // we are; try moving it out of the world
             auto positionDelta = contactCallback.mContactSum;
             // limit rejection delta to the largest known individual rejections
@@ -502,6 +521,11 @@ namespace MWPhysics
                 }
             }
         }
+        else
+        {
+            physicActor->setStuckFrames(0);
+            physicActor->setLastStuckPosition({0, 0, 0});
+        }
 
         collisionObject->setWorldTransform(oldTransform);
         actor.mPosition = tempPosition;