From 6a3ed6c7c19f0c873460097567ee8444237af0cc Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 30 Mar 2025 15:07:16 +0300
Subject: [PATCH] Set physics bodies on different layers based on whether they
 move

This should improve performance when there's a lot of static bodies
compared to moving ones.
---
 source/game/physicssystem.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/source/game/physicssystem.cpp b/source/game/physicssystem.cpp
index 9d5fc47..621b9d1 100644
--- a/source/game/physicssystem.cpp
+++ b/source/game/physicssystem.cpp
@@ -10,6 +10,17 @@ using namespace std;
 
 namespace Msp::Game {
 
+namespace CollisionLayer {
+
+enum
+{
+	STATIC,
+	MOVING
+};
+
+} // namespace CollisionLayer
+
+
 PhysicsSystem::PhysicsSystem(Stage &s):
 	System(s),
 	event_observer(stage.get_event_bus()),
@@ -45,6 +56,9 @@ void PhysicsSystem::early_tick()
 			Handle<Transform> transform = i->entity->get_transform();
 			Physics::MotionType motion = (i->motion ? Physics::DYNAMIC : Physics::STATIC);
 			i->physics_body = make_unique<Physics::RigidBody>(world, i->shape->get_shape(), transform->get_position(), transform->get_rotation(), motion);
+			unsigned layer = (motion==Physics::STATIC ? CollisionLayer::STATIC : CollisionLayer::MOVING);
+			uint32_t collision_mask = (1<<CollisionLayer::STATIC) | (1<<CollisionLayer::MOVING);
+			i->physics_body->set_collisions(layer, collision_mask);
 		}
 	}
 	pending.clear();
-- 
2.45.2