Implement pause-aware picking

This changes the way 2D & 3D physics picking behaves in relation to pause:
- When pause is set, every collision object that is hovered or captured (3D only) is released from that condition, getting the relevant mouse-exit callback., unless its pause mode makes it immune from pause.
- During the pause. picking only considers collision objects immune from pause, sending input events and enter/exit callbacks to them as expected.
- When pause is left, nothing happens. This is a big difference with the classic behavior, which at this point would process all the input events that have been queued against the current state of the 2D/3D world (in other words, checking them against the current position of the objects instead of those at the time of the events).

scene/main/scene_tree.cpp

@@ -409,6 +409,7 @@ bool SceneTree::physics_process(float p_time) {
 	emit_signal("physics_frame");
 
 	_notify_group_pause("physics_process_internal", Node::NOTIFICATION_INTERNAL_PHYSICS_PROCESS);
+	call_group_flags(GROUP_CALL_REALTIME, "_viewports", "_process_picking");
 	_notify_group_pause("physics_process", Node::NOTIFICATION_PHYSICS_PROCESS);
 	_flush_ugc();
 	MessageQueue::get_singleton()->flush(); //small little hack

scene/main/viewport.cpp

@@ -568,8 +568,38 @@ void Viewport::_notification(int p_what) {
 
 				RS::get_singleton()->multimesh_set_visible_instances(contact_3d_debug_multimesh, point_count);
 			}
+		} break;
+		case NOTIFICATION_WM_MOUSE_EXIT: {
+			_drop_physics_mouseover();
+
+			// Unlike on loss of focus (NOTIFICATION_WM_WINDOW_FOCUS_OUT), do not
+			// drop the gui mouseover here, as a scrollbar may be dragged while the
+			// mouse is outside the window (without the window having lost focus).
+			// See bug #39634
+		} break;
+		case NOTIFICATION_WM_WINDOW_FOCUS_OUT: {
+			_drop_physics_mouseover();
+
+			if (gui.mouse_focus && !gui.forced_mouse_focus) {
+				_drop_mouse_focus();
+			}
+		} break;
+	}
+}
+
+void Viewport::_process_picking() {
+	if (!is_inside_tree()) {
+		return;
+	}
+	if (!physics_object_picking) {
+		return;
+	}
+	if (to_screen_rect != Rect2i() && Input::get_singleton()->get_mouse_mode() == Input::MOUSE_MODE_CAPTURED) {
+		return;
+	}
+
+	_drop_physics_mouseover(true);
 
-			if (physics_object_picking && (to_screen_rect == Rect2i() || Input::get_singleton()->get_mouse_mode() != Input::MOUSE_MODE_CAPTURED)) {
 #ifndef _3D_DISABLED
 	Vector2 last_pos(1e20, 1e20);
 	CollisionObject3D *last_object = nullptr;
@@ -700,7 +730,7 @@ void Viewport::_notification(int p_what) {
 				for (int i = 0; i < rc; i++) {
 					if (res[i].collider_id.is_valid() && res[i].collider) {
 						CollisionObject2D *co = Object::cast_to<CollisionObject2D>(res[i].collider);
-									if (co) {
+						if (co && co->can_process()) {
 							bool send_event = true;
 							if (is_mouse) {
 								Map<ObjectID, uint64_t>::Element *F = physics_2d_mouseover.find(res[i].collider_id);
@@ -788,7 +818,7 @@ void Viewport::_notification(int p_what) {
 					ObjectID new_collider;
 					if (col) {
 						CollisionObject3D *co = Object::cast_to<CollisionObject3D>(result.collider);
-									if (co) {
+						if (co && co->can_process()) {
 							_collision_object_input_event(co, camera, ev, result.position, result.normal, result.shape);
 							last_object = co;
 							last_id = result.collider_id;
@@ -823,25 +853,6 @@ void Viewport::_notification(int p_what) {
 		}
 #endif
 	}
-			}
-
-		} break;
-		case NOTIFICATION_WM_MOUSE_EXIT: {
-			_drop_physics_mouseover();
-
-			// Unlike on loss of focus (NOTIFICATION_WM_WINDOW_FOCUS_OUT), do not
-			// drop the gui mouseover here, as a scrollbar may be dragged while the
-			// mouse is outside the window (without the window having lost focus).
-			// See bug #39634
-		} break;
-		case NOTIFICATION_WM_WINDOW_FOCUS_OUT: {
-			_drop_physics_mouseover();
-
-			if (gui.mouse_focus && !gui.forced_mouse_focus) {
-				_drop_mouse_focus();
-			}
-		} break;
-	}
 }
 
 RID Viewport::get_viewport_rid() const {
@@ -2582,28 +2593,41 @@ void Viewport::_drop_mouse_focus() {
 	}
 }
 
-void Viewport::_drop_physics_mouseover() {
+void Viewport::_drop_physics_mouseover(bool p_paused_only) {
 	physics_has_last_mousepos = false;
 
-	while (physics_2d_mouseover.size()) {
-		Object *o = ObjectDB::get_instance(physics_2d_mouseover.front()->key());
+	List<Map<ObjectID, uint64_t>::Element *> to_erase;
+
+	for (Map<ObjectID, uint64_t>::Element *E = physics_2d_mouseover.front(); E; E = E->next()) {
+		Object *o = ObjectDB::get_instance(E->key());
 		if (o) {
 			CollisionObject2D *co = Object::cast_to<CollisionObject2D>(o);
-			co->_mouse_exit();
+			if (co) {
+				if (p_paused_only && co->can_process()) {
+					continue;
 				}
-		physics_2d_mouseover.erase(physics_2d_mouseover.front());
+				co->_mouse_exit();
+				to_erase.push_back(E);
+			}
+		}
+	}
+
+	while (to_erase.size()) {
+		physics_2d_mouseover.erase(to_erase.front()->get());
+		to_erase.pop_front();
 	}
 
 #ifndef _3D_DISABLED
 	if (physics_object_over.is_valid()) {
 		CollisionObject3D *co = Object::cast_to<CollisionObject3D>(ObjectDB::get_instance(physics_object_over));
 		if (co) {
+			if (!(p_paused_only && co->can_process())) {
 				co->_mouse_exit();
-		}
-	}
-
 				physics_object_over = ObjectID();
 				physics_object_capture = ObjectID();
+			}
+		}
+	}
 #endif
 }
 
@@ -3529,6 +3553,8 @@ void Viewport::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_lod_threshold", "pixels"), &Viewport::set_lod_threshold);
 	ClassDB::bind_method(D_METHOD("get_lod_threshold"), &Viewport::get_lod_threshold);
 
+	ClassDB::bind_method(D_METHOD("_process_picking"), &Viewport::_process_picking);
+
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "own_world_3d"), "set_use_own_world_3d", "is_using_own_world_3d");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "world_3d", PROPERTY_HINT_RESOURCE_TYPE, "World3D"), "set_world_3d", "get_world_3d");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "world_2d", PROPERTY_HINT_RESOURCE_TYPE, "World2D", 0), "set_world_2d", "get_world_2d");

scene/main/viewport.h

@@ -450,7 +450,7 @@ private:
 	void _canvas_layer_remove(CanvasLayer *p_canvas_layer);
 
 	void _drop_mouse_focus();
-	void _drop_physics_mouseover();
+	void _drop_physics_mouseover(bool p_paused_only = false);
 
 	void _update_canvas_items(Node *p_node);
 
@@ -479,6 +479,7 @@ protected:
 	bool _is_size_allocated() const;
 
 	void _notification(int p_what);
+	void _process_picking();
 	static void _bind_methods();
 	virtual void _validate_property(PropertyInfo &property) const override;