From 7a67492d81858e53224703d4267dd612e43ae2c8 Mon Sep 17 00:00:00 2001
From: fredzio <chardon.frederic@gmail.com>
Date: Sun, 28 Mar 2021 21:19:14 +0200
Subject: [PATCH] Unbreak SetPos and the mods using it.

To make SetPos works with async physics, it was modified to register a
position offset that would be applied to the real position during the
simulation.

A common pattern to teleport NPC in scripts is a sequence of SetPos/Disable/Enable in the same frame.
Since Disable/Enable creates a new physics actor using last known
RefData::Position, the registered offset never get a chance to be applied.

Modify disable() to call moveObject with the offset applied, so that the newly created physics actor will have up-to-date position
---
 apps/openmw/mwphysics/actor.cpp  |  8 +++++---
 apps/openmw/mwworld/worldimp.cpp | 13 +++++++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/apps/openmw/mwphysics/actor.cpp b/apps/openmw/mwphysics/actor.cpp
index 905034cde5..bf7503e72f 100644
--- a/apps/openmw/mwphysics/actor.cpp
+++ b/apps/openmw/mwphysics/actor.cpp
@@ -123,6 +123,7 @@ void Actor::updatePosition()
     mSimulationPosition = mWorldPosition;
     mStandingOnPtr = nullptr;
     mSkipSimulation = true;
+    mPositionOffset = osg::Vec3f();
 }
 
 void Actor::updateWorldPosition()
@@ -179,9 +180,9 @@ bool Actor::setPosition(const osg::Vec3f& position)
     if (mSkipSimulation)
         return false;
     bool hasChanged = mPosition != position || mPositionOffset.length() != 0 || mWorldPositionChanged;
-    mPreviousPosition = mPosition + mPositionOffset;
-    mPosition = position + mPositionOffset;
-    mPositionOffset = osg::Vec3f();
+    applyOffsetChange();
+    mPreviousPosition = mPosition;
+    mPosition = position;
     return hasChanged;
 }
 
@@ -198,6 +199,7 @@ void Actor::applyOffsetChange()
     mWorldPosition += mPositionOffset;
     mPosition += mPositionOffset;
     mPreviousPosition += mPositionOffset;
+    mSimulationPosition += mPositionOffset;
     mPositionOffset = osg::Vec3f();
     mWorldPositionChanged = true;
 }
diff --git a/apps/openmw/mwworld/worldimp.cpp b/apps/openmw/mwworld/worldimp.cpp
index d6a4de71bd..5e0cdbb2b6 100644
--- a/apps/openmw/mwworld/worldimp.cpp
+++ b/apps/openmw/mwworld/worldimp.cpp
@@ -862,6 +862,19 @@ namespace MWWorld
         if (reference == getPlayerPtr())
             throw std::runtime_error("can not disable player object");
 
+        // A common pattern to teleport NPC in scripts is a sequence of SetPos/Disable/Enable
+        // Disable/Enable create a new physics actor, and so the SetPos call is lost
+        // Call moveObject so that the newly created physics actor will have up-to-date position
+        if (reference.getClass().isActor())
+        {
+            auto* physactor = mPhysics->getActor(reference);
+            if (physactor)
+            {
+                physactor->applyOffsetChange();
+                const auto position = physactor->getSimulationPosition();
+                moveObject(reference, position.x(), position.y(), position.z(), true);
+            }
+        }
         reference.getRefData().disable();
 
         if (reference.getCellRef().getRefNum().hasContentFile())