From dca5c483c4ec2768f95458d1728089b7d3de6029 Mon Sep 17 00:00:00 2001
From: maelstrom <maelstrom@maelstrom.dev>
Date: Sun, 13 Jul 2025 18:37:49 +0200
Subject: [PATCH] fix(workspace): do not fire signals from physics thread as
 lua has to always be executed from main thread

---
 core/src/objects/service/workspace.cpp | 39 +++++++++++++++++++-------
 core/src/objects/service/workspace.h   | 15 ++++++++++
 editor/placedocument.cpp               |  1 +
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/core/src/objects/service/workspace.cpp b/core/src/objects/service/workspace.cpp
index 38dba8e..3c1816d 100644
--- a/core/src/objects/service/workspace.cpp
+++ b/core/src/objects/service/workspace.cpp
@@ -29,26 +29,28 @@ Workspace::~Workspace() {
 PhysicsEventListener::PhysicsEventListener(Workspace* parent) : workspace(parent) {}
 
 void PhysicsEventListener::onContact(const rp::CollisionCallback::CallbackData& data) {
+    workspace->contactQueueLock.lock();
     for (size_t i = 0; i < data.getNbContactPairs(); i++) {
         auto pair = data.getContactPair(i);
         auto type = pair.getEventType();
         if (type == rp::CollisionCallback::ContactPair::EventType::ContactStay) continue;
 
-        auto part0 = reinterpret_cast<Part*>(pair.getBody1()->getUserData())->shared<Part>();
-        auto part1 = reinterpret_cast<Part*>(pair.getBody2()->getUserData())->shared<Part>();
+        if (type == reactphysics3d::CollisionCallback::ContactPair::EventType::ContactStay)
+            continue;
 
-        if (type == reactphysics3d::CollisionCallback::ContactPair::EventType::ContactStart) {
-            part0->Touched->Fire({ (Variant)InstanceRef(part1) });
-            part1->Touched->Fire({ (Variant)InstanceRef(part0) });
-        } else if (type == reactphysics3d::CollisionCallback::ContactPair::EventType::ContactExit) {
-            part0->TouchEnded->Fire({ (Variant)InstanceRef(part1) });
-            part1->TouchEnded->Fire({ (Variant)InstanceRef(part0) });
-        }
+        ContactItem contact;
+        contact.part0 = reinterpret_cast<Part*>(pair.getBody1()->getUserData())->shared<Part>();
+        contact.part1 = reinterpret_cast<Part*>(pair.getBody2()->getUserData())->shared<Part>();
+        contact.action = type == reactphysics3d::CollisionCallback::ContactPair::EventType::ContactStart ? ContactItem::CONTACTITEM_TOUCHED : ContactItem::CONTACTITEM_TOUCHENDED;
+
+        workspace->contactQueue.push(contact);
     }
+    workspace->contactQueueLock.unlock();
 }
 
 void PhysicsEventListener::onTrigger(const rp::OverlapCallback::CallbackData& data) {
-for (size_t i = 0; i < data.getNbOverlappingPairs(); i++) {
+    workspace->contactQueueLock.lock();
+    for (size_t i = 0; i < data.getNbOverlappingPairs(); i++) {
         auto pair = data.getOverlappingPair(i);
         auto type = pair.getEventType();
         if (type == rp::OverlapCallback::OverlapPair::EventType::OverlapStay) continue;
@@ -64,6 +66,7 @@ for (size_t i = 0; i < data.getNbOverlappingPairs(); i++) {
             part1->TouchEnded->Fire({ (Variant)InstanceRef(part0) });
         }
     }
+    workspace->contactQueueLock.unlock();
 }
 
 void Workspace::InitService() {
@@ -143,6 +146,22 @@ void Workspace::updatePartPhysics(std::shared_ptr<Part> part) {
     part->rigidBody->setUserData(&*part);
 }
 
+void Workspace::ProcessContactEvents() {
+    contactQueueLock.lock();
+    while (!contactQueue.empty()) {
+        ContactItem& contact = contactQueue.front();
+        contactQueue.pop();
+        if (contact.action == ContactItem::CONTACTITEM_TOUCHED) {
+            contact.part0->Touched->Fire({ (Variant)InstanceRef(contact.part1) });
+            contact.part1->Touched->Fire({ (Variant)InstanceRef(contact.part0) });
+        } else if (contact.action == ContactItem::CONTACTITEM_TOUCHENDED) {
+            contact.part0->TouchEnded->Fire({ (Variant)InstanceRef(contact.part1) });
+            contact.part1->TouchEnded->Fire({ (Variant)InstanceRef(contact.part0) });
+        }
+    }
+    contactQueueLock.unlock();
+}
+
 void Workspace::SyncPartPhysics(std::shared_ptr<Part> part) {
     if (globalPhysicsLock.try_lock()) {
         updatePartPhysics(part);
diff --git a/core/src/objects/service/workspace.h b/core/src/objects/service/workspace.h
index 4111680..4cb8e21 100644
--- a/core/src/objects/service/workspace.h
+++ b/core/src/objects/service/workspace.h
@@ -7,6 +7,7 @@
 #include <list>
 #include <memory>
 #include <mutex>
+#include <queue>
 #include <reactphysics3d/body/RigidBody.h>
 #include <reactphysics3d/engine/EventListener.h>
 #include <reactphysics3d/engine/PhysicsCommon.h>
@@ -52,6 +53,15 @@ struct QueueItem {
     } action;
 };
 
+struct ContactItem {
+    std::shared_ptr<Part> part0;
+    std::shared_ptr<Part> part1;
+    enum {
+        CONTACTITEM_TOUCHED,
+        CONTACTITEM_TOUCHENDED,
+    } action;
+};
+
 class Workspace;
 class PhysicsEventListener : public rp::EventListener {
     friend Workspace;
@@ -66,8 +76,12 @@ class PhysicsEventListener : public rp::EventListener {
 class DEF_INST_SERVICE_(explorer_icon="workspace") Workspace : public Service {
     AUTOGEN_PREAMBLE
     
+    friend PhysicsEventListener;
+    
     std::list<std::shared_ptr<Part>> simulatedBodies;
     std::list<QueueItem> bodyQueue;
+    std::queue<ContactItem> contactQueue;
+    std::mutex contactQueueLock;
     rp::PhysicsWorld* physicsWorld;
     static rp::PhysicsCommon* physicsCommon;
     PhysicsEventListener physicsEventListener;
@@ -97,6 +111,7 @@ public:
     rp::Joint* CreateJoint(const rp::JointInfo& jointInfo);
     void DestroyJoint(rp::Joint* joint);
 
+    void ProcessContactEvents();
     void PhysicsStep(float deltaTime);
     std::optional<const RaycastResult> CastRayNearest(glm::vec3 point, glm::vec3 rotation, float maxLength, std::optional<RaycastFilter> filter = std::nullopt, unsigned short categoryMaskBits = 0xFFFF);
 };
\ No newline at end of file
diff --git a/editor/placedocument.cpp b/editor/placedocument.cpp
index 3ed1253..98e9a8d 100644
--- a/editor/placedocument.cpp
+++ b/editor/placedocument.cpp
@@ -140,6 +140,7 @@ void PlaceDocument::timerEvent(QTimerEvent* evt) {
     placeWidget->repaint();
     placeWidget->updateCycle();
     gDataModel->GetService<ScriptContext>()->RunSleepingThreads();
+    gDataModel->GetService<Workspace>()->ProcessContactEvents();
 }