From 8b27ceab695cc1eb6965c1e7fe23b931eae44a01 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 22 Mar 2025 12:28:16 +0200
Subject: [PATCH] Convert TransformPropagator to a Transactor

The propagation is now done automatically after any system modifies
transforms.
---
 source/game/director.cpp            |  3 +--
 source/game/physicssystem.cpp       |  1 -
 source/game/transform.h             |  3 +++
 source/game/transformpropagator.cpp | 19 +++++++++++--------
 source/game/transformpropagator.h   |  6 +++---
 5 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/source/game/director.cpp b/source/game/director.cpp
index d2e0206..374f91e 100644
--- a/source/game/director.cpp
+++ b/source/game/director.cpp
@@ -4,7 +4,7 @@
 #include "component.h"
 #include "entity.h"
 #include "stage.h"
-#include "transformpropagator.h"
+#include "system.h"
 
 using namespace std;
 
@@ -31,7 +31,6 @@ Director::~Director()
 Stage &Director::create_stage(const string &n)
 {
 	Stage &stage = *stages.emplace_back(std::make_unique<Stage>(n, thread_pool, reflector, resources));
-	stage.add_system<TransformPropagator>();
 	event_source.emit<Events::StageCreated>(stage);
 	return stage;
 }
diff --git a/source/game/physicssystem.cpp b/source/game/physicssystem.cpp
index 4afb09c..9d5fc47 100644
--- a/source/game/physicssystem.cpp
+++ b/source/game/physicssystem.cpp
@@ -18,7 +18,6 @@ PhysicsSystem::PhysicsSystem(Stage &s):
 {
 	declare_dependency<Transform>(CHAINED_UPDATE);
 	declare_dependency<Motion>(CHAINED_UPDATE);
-	declare_dependency<TransformPropagator>(RUN_BEFORE);
 
 	monitor.set_changed_callback([this](auto &b){ simulated_rigid_body_changed(b); });
 }
diff --git a/source/game/transform.h b/source/game/transform.h
index 249e732..4dd2fbc 100644
--- a/source/game/transform.h
+++ b/source/game/transform.h
@@ -6,6 +6,7 @@
 #include <msp/linal/vector.h>
 #include "component.h"
 #include "mspgame_api.h"
+#include "transformpropagator.h"
 
 namespace Msp::Game {
 
@@ -35,6 +36,8 @@ struct TransformData
 class MSPGAME_API Transform: public BufferedComponent<TransformData>
 {
 public:
+	using Transactor = TransformPropagator;
+
 	Transform(Handle<Entity> e): BufferedComponent(e) { }
 
 	void set_values(const TransformValues &);
diff --git a/source/game/transformpropagator.cpp b/source/game/transformpropagator.cpp
index cadac04..86da2d1 100644
--- a/source/game/transformpropagator.cpp
+++ b/source/game/transformpropagator.cpp
@@ -9,22 +9,25 @@ using namespace std;
 namespace Msp::Game {
 
 TransformPropagator::TransformPropagator(Stage &s):
-	System(s),
+	BasicTransactor(s),
 	observer(s.get_event_bus())
 {
-	declare_dependency<Transform>(CHAINED_UPDATE);
-
 	observer.observe<Events::EntityCreated>([this](auto &){ transforms_dirty = true; });
 	observer.observe<Events::EntityDestroyed>([this](auto &){ transforms_dirty = true; });
 }
 
-void TransformPropagator::tick(Time::TimeDelta)
+void TransformPropagator::commit(Mode mode)
 {
-	if(transforms_dirty)
-		rebuild_transform_order();
+	if(mode&WRITE)
+	{
+		if(transforms_dirty)
+			rebuild_transform_order();
+
+		for(const ParentedTransform &t: transforms)
+			t.transform->update_world_matrix(t.parent.get());
+	}
 
-	for(const ParentedTransform &t: transforms)
-		t.transform->update_world_matrix(t.parent.get());
+	BasicTransactor::commit(mode);
 }
 
 void TransformPropagator::rebuild_transform_order()
diff --git a/source/game/transformpropagator.h b/source/game/transformpropagator.h
index defaed1..daa7c2b 100644
--- a/source/game/transformpropagator.h
+++ b/source/game/transformpropagator.h
@@ -4,14 +4,14 @@
 #include "eventobserver.h"
 #include "handle.h"
 #include "mspgame_api.h"
-#include "system.h"
+#include "transactor.h"
 
 namespace Msp::Game {
 
 class Entity;
 class Transform;
 
-class MSPGAME_API TransformPropagator: public System
+class MSPGAME_API TransformPropagator: public BasicTransactor<Transform>
 {
 private:
 	struct ParentedTransform
@@ -27,7 +27,7 @@ private:
 public:
 	TransformPropagator(Stage &);
 
-	void tick(Time::TimeDelta) override;
+	void commit(Mode) override;
 
 private:
 	void rebuild_transform_order();
-- 
2.45.2