From 650ba0068a54f04384268e37204d70a4f2d57ace Mon Sep 17 00:00:00 2001
From: maelstrom <maelstrom@maelstrom.dev>
Date: Mon, 7 Jul 2025 20:29:00 +0200
Subject: [PATCH] fix(physics): crash when deleting parts due to misusing
 simulationTicket iterator

---
 core/src/objects/part.cpp              | 2 +-
 core/src/objects/part.h                | 2 +-
 core/src/objects/service/workspace.cpp | 6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/core/src/objects/part.cpp b/core/src/objects/part.cpp
index 07ae7ce..4633923 100644
--- a/core/src/objects/part.cpp
+++ b/core/src/objects/part.cpp
@@ -54,7 +54,7 @@ void Part::OnWorkspaceAdded(std::optional<std::shared_ptr<Workspace>> oldWorkspa
 }
 
 void Part::OnWorkspaceRemoved(std::shared_ptr<Workspace> oldWorkspace) {
-    if (simulationTicket->get() != nullptr)
+    if (simulationTicket.has_value())
         oldWorkspace->RemoveBody(shared<Part>());
 }
 
diff --git a/core/src/objects/part.h b/core/src/objects/part.h
index f2c5558..bc3a622 100644
--- a/core/src/objects/part.h
+++ b/core/src/objects/part.h
@@ -109,7 +109,7 @@ public:
     DEF_SIGNAL SignalSource TouchEnded;
 
     rp::RigidBody* rigidBody = nullptr;
-    SimulationTicket simulationTicket;
+    std::optional<SimulationTicket> simulationTicket;
     bool rigidBodyDirty = true;
     
     inline SurfaceType GetSurfaceFromFace(NormalId face) { return surfaceFromFace(face); }
diff --git a/core/src/objects/service/workspace.cpp b/core/src/objects/service/workspace.cpp
index 2636c39..38dba8e 100644
--- a/core/src/objects/service/workspace.cpp
+++ b/core/src/objects/service/workspace.cpp
@@ -165,9 +165,9 @@ void Workspace::PhysicsStep(float deltaTime) {
         if (item.action == QueueItem::QUEUEITEM_ADD) {
             simulatedBodies.push_back(item.part);
             item.part->simulationTicket = --simulatedBodies.end();
-        } else if (item.part->simulationTicket->get() != nullptr) {
-            simulatedBodies.erase(item.part->simulationTicket);
-            item.part->simulationTicket = {};
+        } else if (item.part->simulationTicket.has_value()) {
+            simulatedBodies.erase(item.part->simulationTicket.value());
+            item.part->simulationTicket = std::nullopt;
         }
     }
     queueLock.unlock();