Actor's position can be determined in 3 ways:
1/ as a result of physics simulation
2/ after a script require a relative position change (SetPos, Move)
3/ absolutely set from games mechanics event (teleport) or script
(PositionCell)
In case 1/, RefData::mPosition is updated with the physics simulation result
In case 2/, when RefData::mPosition is updated, physics simulation is informed of the change and update accordingly
In case 3/, when RefData::mPosition is updated, the physics simulation state is reset
In all 3 cases, we don't need to check the RefData::mPosition to get a
correct behaviour.
TSAN reported the following data race:
Read of size 4 at 0x7b50005b75b0 by thread T12 (mutexes: write M656173, write M84859534346343880):
#0 ESM::Position::asVec3() const /build/openmw/openmw/master2/.build/freebsd/TSAN/../../.././components/esm/defs.hpp:55:27 (openmw+0xb809d5)
#1 MWPhysics::Actor::updateWorldPosition() /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/actor.cpp:131:59 (openmw+0xb809d5)
#2 MWPhysics::Actor::setPosition(osg::Vec3f const&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/actor.cpp:177:5 (openmw+0xb809d5)
#3 MWPhysics::PhysicsTaskScheduler::updateActorsPositions() /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/mtphysics.cpp:524:28 (openmw+0xb91ac0)
#4 MWPhysics::PhysicsTaskScheduler::afterPostStep() /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/mtphysics.cpp:614:13 (openmw+0xb915e7)
#5 MWPhysics::PhysicsTaskScheduler::worker()::$_5::operator()() const /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/mtphysics.cpp:498:45 (openmw+0xb915e7)
#6 void Misc::Barrier::wait<MWPhysics::PhysicsTaskScheduler::worker()::$_5>(MWPhysics::PhysicsTaskScheduler::worker()::$_5&&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../.././components/misc/barrier.hpp:30:21 (openmw+0xb915e7)
#7 MWPhysics::PhysicsTaskScheduler::worker() /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/mtphysics.cpp:498:31 (openmw+0xb915e7)
#8 MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0::operator()() const /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwphysics/mtphysics.cpp:162:45 (openmw+0xb92630)
#9 decltype(std::__1::forward<MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0>(fp)()) std::__1::__invoke<MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0>(MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0&&) /usr/include/c++/v1/type_traits:3899:1 (openmw+0xb92630)
#10 void std::__1::__thread_execute<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0>(std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0>&, std::__1::__tuple_indices<>) /usr/include/c++/v1/thread:280:5 (openmw+0xb92630)
#11 void* std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, MWPhysics::PhysicsTaskScheduler::PhysicsTaskScheduler(float, btCollisionWorld*, MWRender::DebugDrawer*)::$_0> >(void*) /usr/include/c++/v1/thread:291:5 (openmw+0xb92630)
Previous write of size 8 at 0x7b50005b75b0 by main thread:
#0 memcpy /wrkdirs/usr/ports/devel/llvm-devel/work-default/llvm-project-3f6753efe1990a928ed120bd907940a9fb3e2fc3/compiler-rt/lib/tsan/../sanitizer_common/sanitizer_common_interceptors.inc:827:5 (openmw+0x55a057)
#1 MWWorld::RefData::setPosition(ESM::Position const&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwworld/refdata.cpp:216:19 (openmw+0xa3de1c)
#2 MWWorld::World::moveObject(MWWorld::Ptr const&, MWWorld::CellStore*, float, float, float, bool) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwworld/worldimp.cpp:1130:26 (openmw+0xa57300)
#3 MWWorld::World::moveObject(MWWorld::Ptr const&, float, float, float, bool, bool) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwworld/worldimp.cpp:1253:16 (openmw+0xa580c8)
#4 MWWorld::World::doPhysics(float, unsigned long long, unsigned int, osg::Stats&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwworld/worldimp.cpp:1530:17 (openmw+0xa5af8f)
#5 MWWorld::World::updatePhysics(float, bool, unsigned long long, unsigned int, osg::Stats&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/mwworld/worldimp.cpp:1862:13 (openmw+0xa61a7c)
#6 OMW::Engine::frame(float) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/engine.cpp:333:42 (openmw+0xcce9e7)
#7 OMW::Engine::go() /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/engine.cpp:935:14 (openmw+0xcd86ed)
#8 runApplication(int, char**) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/main.cpp:296:17 (openmw+0xcbffac)
#9 wrapApplication(int (*)(int, char**), int, char**, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../components/debug/debugging.cpp:205:15 (openmw+0x1335442)
#10 main /build/openmw/openmw/master2/.build/freebsd/TSAN/../../../apps/openmw/main.cpp:308:12 (openmw+0xcc008a)
:wqa
Previous MR change the meaning of mPositionOffset: it is now just a log
of relative movement that were already applied to allow the physics
simulation to catch up, instead of changes that needs to be applied. As
such, after a teleport we need to reset it. Also, since mWorldPosition
is already with the offset we should not update its value in
applyPositionOffset().
Instead of registering the desired change of position and rely on
physics simulation to apply it to the world, immediately change the
position in the world without reset the simulation.
When a script calls SetPos for x,y,z in sequence on an actor, we need to make sure
that the actor will not spawn under ground at x,y coordinates.
Now that change of coordinates are cumulated and applied all at once, we
need to account for the whole offset.
To this end move the terrain height check inside of Actor class.
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
When a position is forced, the actor position in physics subsystem is
overriden. The background physics thread is not made aware of this,
its result are simply discarded.
There is a short window where this doesn't work (in this
example, actor is at A and script moves it to B)
1) actor position is set to B. (among others, Actor::mPosition is set to B)
2) physics thread reset Actor::mPosition with stale value (around A)
3) main thread read simulation result, reset Actor::mSkipSimulation flag => actor is at B
4) physics thread fetch latest Actor::mPosition value, which is around A
5) main thread read simulation result, actor is around A
To avoid this situation, do not perform 2) until after 3) occurs. This
way, at 4) starts the simulation with up-to-date Actor::mPosition
Restore projectile caster from savegame (#5860)
See merge request OpenMW/openmw!616
(cherry picked from commit d595c7adb0fb45eafed6d3d0403ad640a91411ed)
c5426bec In the savegame, projectile caster is identified by its actor id. When
This enables accelleration of heightfield collisions.
Unfortunately, `btHeightfieldTerrainShape::processAllTriangle` does not
yet use the accellerator data, so this change does not improve
performance yet but might do so in future bullet versions.
References:
* Accellerator introduced in:
https://github.com/bulletphysics/bullet3/pull/2062
* Feature request to use the accellerator in `processAllTriangle`:
https://github.com/bulletphysics/bullet3/issues/3276
projectile collision shape.
A side effect of moving actors outside of projectile collision shape is that if both the actor and the projectile are
near a wall, the actor could get moved outside of the world.
