Make physics interpolation compatible with separate-thread rendering

Author: RandomShaper

main/main.cpp

@@ -2340,6 +2340,8 @@ bool Main::iteration() {
 	double step = advance.idle_step;
 	double scaled_step = step * time_scale;
 
+	VisualServer::get_singleton()->sync_and_halt();
+
 	Engine::get_singleton()->_frame_step = step;
 	Engine::get_singleton()->_physics_interpolation_fraction = advance.interpolation_fraction;
 
@@ -2379,12 +2381,16 @@ bool Main::iteration() {
 		Physics2DServer::get_singleton()->sync();
 		Physics2DServer::get_singleton()->flush_queries();
 
+		VisualServer::get_singleton()->thaw();
+
 		if (OS::get_singleton()->get_main_loop()->iteration(frame_slice * time_scale)) {
 			exit = true;
 			Engine::get_singleton()->_in_physics = false;
 			break;
 		}
 
+		VisualServer::get_singleton()->sync_and_halt();
+
 		NavigationServer::get_singleton_mut()->process(frame_slice * time_scale);
 		message_queue->flush();
 
@@ -2403,6 +2409,8 @@ bool Main::iteration() {
 		Engine::get_singleton()->_in_physics = false;
 	}
 
+	VisualServer::get_singleton()->thaw();
+
 	if (InputDefault::get_singleton()->is_using_input_buffering() && agile_input_event_flushing) {
 		InputDefault::get_singleton()->flush_buffered_events();
 	}

servers/visual/visual_server_raster.cpp

@@ -133,9 +133,16 @@ void VisualServerRaster::draw(bool p_swap_buffers, double frame_step) {
 	}
 	VS::get_singleton()->emit_signal("frame_post_draw");
 }
+
 void VisualServerRaster::sync() {
 }
 
+void VisualServerRaster::sync_and_halt() {
+}
+
+void VisualServerRaster::thaw() {
+}
+
 void VisualServerRaster::set_physics_interpolation_enabled(bool p_enabled) {
 	VSG::scene->set_physics_interpolation_enabled(p_enabled);
 	VSG::canvas->set_physics_interpolation_enabled(p_enabled);

servers/visual/visual_server_raster.h

@@ -784,6 +784,8 @@ class VisualServerRaster : public VisualServer {
 	virtual void pre_draw(bool p_will_draw);
 	virtual void draw(bool p_swap_buffers, double frame_step);
 	virtual void sync();
+	virtual void sync_and_halt();
+	virtual void thaw();
 	virtual bool has_changed(ChangedPriority p_priority = CHANGED_PRIORITY_ANY) const;
 	virtual void init();
 	virtual void finish();

servers/visual/visual_server_wrap_mt.cpp

@@ -43,6 +43,10 @@ void VisualServerWrapMT::thread_draw(bool p_swap_buffers, double frame_step) {
 void VisualServerWrapMT::thread_flush() {
 }
 
+void VisualServerWrapMT::thread_halt() {
+	thread_halt_semaphore.wait();
+}
+
 void VisualServerWrapMT::_thread_callback(void *_instance) {
 	VisualServerWrapMT *vsmt = reinterpret_cast<VisualServerWrapMT *>(_instance);
 
@@ -102,6 +106,19 @@ void VisualServerWrapMT::sync() {
 	}
 }
 
+void VisualServerWrapMT::sync_and_halt() {
+	if (create_thread) {
+		command_queue.push_and_sync(this, &VisualServerWrapMT::thread_flush);
+		command_queue.push(this, &VisualServerWrapMT::thread_halt);
+	}
+}
+
+void VisualServerWrapMT::thaw() {
+	if (create_thread) {
+		thread_halt_semaphore.post();
+	}
+}
+
 void VisualServerWrapMT::draw(bool p_swap_buffers, double frame_step) {
 	if (create_thread) {
 		command_queue.push(this, &VisualServerWrapMT::thread_draw, p_swap_buffers, frame_step);

servers/visual/visual_server_wrap_mt.h

@@ -54,6 +54,9 @@ class VisualServerWrapMT : public VisualServer {
 	void thread_draw(bool p_swap_buffers, double frame_step);
 	void thread_flush();
 
+	Semaphore thread_halt_semaphore;
+	void thread_halt();
+
 	void thread_exit();
 
 	Mutex alloc_mutex;
@@ -690,6 +693,8 @@ class VisualServerWrapMT : public VisualServer {
 	virtual void pre_draw(bool p_will_draw);
 	virtual void draw(bool p_swap_buffers, double frame_step);
 	virtual void sync();
+	virtual void sync_and_halt();
+	virtual void thaw();
 	FUNC1RC(bool, has_changed, ChangedPriority)
 	virtual void set_physics_interpolation_enabled(bool p_enabled);
 

servers/visual_server.h

@@ -1163,6 +1163,8 @@ class VisualServer : public Object {
 
 	virtual void draw(bool p_swap_buffers = true, double frame_step = 0.0) = 0;
 	virtual void sync() = 0;
+	virtual void sync_and_halt() = 0;
+	virtual void thaw() = 0;
 	virtual bool has_changed(ChangedPriority p_priority = CHANGED_PRIORITY_ANY) const = 0;
 	virtual void init() = 0;
 	virtual void finish() = 0;