feat: implement type-safe ReferenceProperty for SmartPointer fields and add UI support for object selection via context-aware dropdowns

app/gcompose/src/ContextPanel.cpp

@@ -90,6 +90,10 @@ void ContextPanel::setContext(uLib::ObjectsContext* context) {
     m_treeView->expandAll();
 }
 
+void ContextPanel::setPropertyContext(uLib::ObjectsContext* context) {
+    m_propertiesPanel->setContext(context);
+}
+
 void ContextPanel::onSelectionChanged(const QItemSelection& selected, const QItemSelection& deselected) {
     uLib::Object* target = nullptr;
     if (!selected.indexes().isEmpty()) {

app/gcompose/src/ContextPanel.h

@@ -20,6 +20,7 @@ public:
     ~ContextPanel();
 
     void setContext(uLib::ObjectsContext* context);
+    void setPropertyContext(uLib::ObjectsContext* context);
     void selectObject(uLib::Object* obj);
     void clearSelection();
 

app/gcompose/src/MainPanel.cpp

@@ -128,6 +128,9 @@ void MainPanel::setContext(uLib::ObjectsContext* context) {
     m_context = context;
     m_contextPanel->setContext(context);
     
+    // Propagate context to all panels for reference property dropdowns
+    m_contextPanel->setPropertyContext(context);
+    m_firstPane->setContext(context);
     if (m_mainVtkContext) {
         if (auto* viewport = qobject_cast<uLib::Vtk::QViewport*>(m_firstPane->currentViewport())) {
             viewport->RemoveProp3D(*m_mainVtkContext);

app/gcompose/src/PropertiesPanel.cpp

@@ -47,4 +47,8 @@ void PropertiesPanel::setObject(uLib::Object* obj) {
     m_editor->setObject(obj);
 }
 
+void PropertiesPanel::setContext(uLib::ObjectsContext* context) {
+    m_editor->setContext(context);
+}
+
 PropertiesPanel::~PropertiesPanel() {}

app/gcompose/src/PropertiesPanel.h

@@ -5,6 +5,7 @@
 
 namespace uLib {
     class Object;
+    class ObjectsContext;
     namespace Qt { class PropertyEditor; }
 }
 
@@ -24,6 +25,9 @@ public:
     /** @brief Sets the object to be inspected. */
     void setObject(uLib::Object* obj);
     
+    /** @brief Sets the context for reference property dropdowns. */
+    void setContext(uLib::ObjectsContext* context);
+
 signals:
     void propertyUpdated();
 

app/gcompose/src/PropertyWidgets.cpp

@@ -13,6 +13,7 @@
 #include <QSlider>
 #include <QFontDialog>
 #include "Settings.h"
+#include "Core/ObjectsContext.h"
 
 namespace uLib {
 namespace Qt {
@@ -386,7 +387,74 @@ public:
     }
 };
 
-PropertyEditor::PropertyEditor(QWidget* parent) : QWidget(parent), m_Object(nullptr) {
+////////////////////////////////////////////////////////////////////////////////
+// ReferencePropertyWidget
+
+ReferencePropertyWidget::ReferencePropertyWidget(ReferencePropertyBase* prop, ::uLib::ObjectsContext* context, QWidget* parent)
+    : PropertyWidgetBase(prop, parent), m_RefProp(prop), m_Context(context) {
+    m_Combo = new QComboBox(static_cast<QWidget*>(this));
+    m_Layout->addWidget(m_Combo, 1);
+    refreshCombo();
+    connect(m_Combo, &QComboBox::currentIndexChanged, this, &ReferencePropertyWidget::onComboChanged);
+
+    // Listen for property updates to refresh selected item
+    m_Connection = uLib::Object::connect(prop, &uLib::Object::Updated, [this](){
+        QSignalBlocker blocker(m_Combo);
+        refreshCombo();
+    });
+
+    // Listen for context changes to refresh the dropdown list
+    if (m_Context) {
+        m_ContextConnection = uLib::Object::connect(m_Context, &uLib::Object::Updated, [this](){
+            QSignalBlocker blocker(m_Combo);
+            refreshCombo();
+        });
+    }
+}
+
+ReferencePropertyWidget::~ReferencePropertyWidget() {
+    m_Connection.disconnect();
+    m_ContextConnection.disconnect();
+}
+
+void ReferencePropertyWidget::refreshCombo() {
+    m_Combo->clear();
+    m_Combo->addItem("(none)", QVariant::fromValue((quintptr)0));
+
+    int selectedIdx = 0;
+    Object* currentRef = m_RefProp->GetReferencedObject();
+
+    if (m_Context) {
+        const auto& objects = m_Context->GetObjects();
+        for (auto* obj : objects) {
+            if (m_RefProp->IsCompatible(obj)) {
+                QString label = QString::fromStdString(obj->GetInstanceName());
+                if (label.isEmpty()) {
+                    label = QString::fromStdString(std::string(obj->GetClassName()));
+                }
+                // Add index suffix if name is empty to disambiguate
+                m_Combo->addItem(label, QVariant::fromValue((quintptr)obj));
+                if (obj == currentRef) {
+                    selectedIdx = m_Combo->count() - 1;
+                }
+            }
+        }
+    }
+    m_Combo->setCurrentIndex(selectedIdx);
+}
+
+void ReferencePropertyWidget::onComboChanged(int index) {
+    if (index < 0) return;
+    quintptr ptr = m_Combo->itemData(index).value<quintptr>();
+    Object* obj = reinterpret_cast<Object*>(ptr);
+    m_RefProp->SetReferencedObject(obj);
+    Q_EMIT updated();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// PropertyEditor
+
+PropertyEditor::PropertyEditor(QWidget* parent) : QWidget(parent), m_Object(nullptr), m_Context(nullptr) {
     m_MainLayout = new QVBoxLayout(this);
     m_MainLayout->setContentsMargins(0, 0, 0, 0);
     m_ScrollArea = new QScrollArea(this);
@@ -488,18 +556,23 @@ void PropertyEditor::setObject(::uLib::Object* obj, bool displayOnly) {
                      // widget = new RangePropertyWidget<float>(pflt, m_Container);
                 }
             } else {
-                // Priority 2: Standard factory lookup
+                // Priority 2: Check for reference properties (SmartPointer<T>)
+                if (auto* refProp = dynamic_cast<::uLib::ReferencePropertyBase*>(prop)) {
+                    widget = static_cast<QWidget*>(new ReferencePropertyWidget(refProp, m_Context, m_Container));
+                } else {
+                    // Priority 3: Standard factory lookup
                     auto it = m_Factories.find(prop->GetTypeIndex());
                     if (it != m_Factories.end()) {
                         widget = it->second(prop, m_Container);
                     } else {
-                    // Debug info for unknown types
-                    std::cout << "PropertyEditor: No factory for " << prop->GetQualifiedName() 
-                              << " (Type: " << prop->GetTypeName() << ")" << std::endl;
+                        // Debug info for unknown types
+                        std::cout << "PropertyEditor: No factory for " << prop->GetQualifiedName() 
+                                  << " (Type: " << prop->GetTypeName() << ")" << std::endl;
 
                         widget = new PropertyWidgetBase(prop, m_Container);
-                    widget->layout()->addWidget(new QLabel("(Read-only: " + QString::fromStdString(prop->GetValueAsString()) + ")"));
+                        widget->layout()->addWidget(new QLabel("(Read-only: " + QString::fromStdString(prop->GetValueAsString()) + ")"));
                     }
+                }
             }
 
             if (widget) {

app/gcompose/src/PropertyWidgets.h

@@ -4,6 +4,7 @@
 #include <QWidget>
 class QPushButton;
 class QSlider;
+class QComboBox;
 #include <QLabel>
 #include <QHBoxLayout>
 #include <QVBoxLayout>
@@ -21,6 +22,8 @@ class QSlider;
 #include "Math/Dense.h"
 #include "Settings.h"
 
+namespace uLib { class ObjectsContext; }
+
 namespace uLib {
 namespace Qt {
 
@@ -211,12 +214,28 @@ private:
     QPushButton* m_Button;
 };
 
+class ReferencePropertyWidget : public PropertyWidgetBase {
+    Q_OBJECT
+public:
+    ReferencePropertyWidget(ReferencePropertyBase* prop, ::uLib::ObjectsContext* context, QWidget* parent = nullptr);
+    virtual ~ReferencePropertyWidget();
+private slots:
+    void onComboChanged(int index);
+private:
+    void refreshCombo();
+    ReferencePropertyBase* m_RefProp;
+    ::uLib::ObjectsContext* m_Context;
+    QComboBox* m_Combo;
+    Connection m_ContextConnection;
+};
+
 class PropertyEditor : public QWidget {
     Q_OBJECT
 public:
     PropertyEditor(QWidget* parent = nullptr);
     virtual ~PropertyEditor();
     void setObject(uLib::Object* obj, bool displayOnly = false);
+    void setContext(uLib::ObjectsContext* context) { m_Context = context; }
     template<typename T>
     void registerFactory(std::function<QWidget*(PropertyBase*, QWidget*)> factory) {
         m_Factories[std::type_index(typeid(T))] = factory;
@@ -228,6 +247,7 @@ signals:
 private:
     void clear();
     uLib::Object* m_Object;
+    uLib::ObjectsContext* m_Context;
     QVBoxLayout* m_MainLayout;
     QScrollArea* m_ScrollArea;
     QWidget* m_Container;

app/gcompose/src/ViewportPane.cpp

@@ -113,6 +113,10 @@ void ViewportPane::setObject(uLib::Object* obj) {
     }
 }
 
+void ViewportPane::setContext(uLib::ObjectsContext* context) {
+    m_displayEditor->setContext(context);
+}
+
 void ViewportPane::setViewport(QWidget* viewport, const QString& title) {
     if (m_viewport) {
         delete m_viewport;

app/gcompose/src/ViewportPane.h

@@ -7,6 +7,7 @@
 
 namespace uLib {
     class Object;
+    class ObjectsContext;
     namespace Qt { class PropertyEditor; }
     namespace Vtk { class Viewport; }
 }
@@ -30,6 +31,9 @@ public:
     /** @brief Update the display properties for the given object. */
     void setObject(uLib::Object* obj);
     
+    /** @brief Sets the context for reference property dropdowns. */
+    void setContext(uLib::ObjectsContext* context);
+
 private slots:
     void onCloseRequested();
     void showContextMenu(const QPoint& pos);

src/Core/Property.h

@@ -15,6 +15,15 @@
 #include "Core/Archives.h"
 #include "Core/Signal.h"
 #include "Core/Object.h"
+#include "Core/SmartPointer.h"
+
+// Type traits for detecting SmartPointer<T>
+namespace uLib {
+template<typename T> struct is_smart_pointer : std::false_type {};
+template<typename T> struct is_smart_pointer<SmartPointer<T>> : std::true_type {};
+template<typename T> struct smart_pointer_element { using type = void; };
+template<typename T> struct smart_pointer_element<SmartPointer<T>> { using type = T; };
+} // namespace uLib
 
 namespace uLib {
 
@@ -216,6 +225,109 @@ private:
 
 } // namespace uLib
 
+namespace uLib {
+
+/**
+ * @brief Base class for reference properties (SmartPointer<T> fields).
+ * Provides a type-erased interface for getting/setting object references
+ * and checking type compatibility.
+ */
+class ReferencePropertyBase : public PropertyBase {
+public:
+  virtual ~ReferencePropertyBase() {}
+  virtual Object* GetReferencedObject() const = 0;
+  virtual void SetReferencedObject(Object* obj) = 0;
+  virtual bool IsCompatible(Object* obj) const = 0;
+  virtual const char* GetReferenceTypeName() const = 0;
+};
+
+/**
+ * @brief Typed reference property for SmartPointer<T> fields.
+ * Filters context objects by dynamic_cast compatibility with T.
+ */
+template <typename T>
+class ReferenceProperty : public ReferencePropertyBase {
+public:
+  ReferenceProperty(Object* owner, const std::string& name, SmartPointer<T>& ref,
+                    const std::string& units = "", const std::string& group = "")
+    : m_owner(owner), m_name(name), m_units(units), m_group(group), m_ref(ref), m_ReadOnly(false) {
+      if (m_owner) m_owner->RegisterProperty(this);
+  }
+
+  virtual ~ReferenceProperty() {}
+
+  // PropertyBase interface
+  virtual const std::string& GetName() const override { return m_name; }
+  virtual const char* GetTypeName() const override { return typeid(SmartPointer<T>).name(); }
+  virtual std::type_index GetTypeIndex() const override { return std::type_index(typeid(ReferencePropertyBase)); }
+  virtual const std::string& GetUnits() const override { return m_units; }
+  virtual void SetUnits(const std::string& units) override { m_units = units; }
+  virtual const std::string& GetGroup() const override { return m_group; }
+  virtual void SetGroup(const std::string& group) override { m_group = group; }
+  virtual bool IsReadOnly() const override { return m_ReadOnly; }
+  void SetReadOnly(bool ro) { m_ReadOnly = ro; }
+
+  virtual std::string GetValueAsString() const override {
+    T* ptr = m_ref.Get();
+    if (!ptr) return "(none)";
+    Object* obj = dynamic_cast<Object*>(ptr);
+    if (obj) {
+      std::string iname = obj->GetInstanceName();
+      if (!iname.empty()) return iname;
+      return obj->GetClassName();
+    }
+    return "(set)";
+  }
+
+  // ReferencePropertyBase interface
+  virtual Object* GetReferencedObject() const override {
+    return dynamic_cast<Object*>(m_ref.Get());
+  }
+
+  virtual void SetReferencedObject(Object* obj) override {
+    if (!obj) {
+      m_ref = SmartPointer<T>(nullptr);
+      this->Updated();
+      if (m_owner) m_owner->Updated();
+      return;
+    }
+    T* casted = dynamic_cast<T*>(obj);
+    if (casted) {
+      m_ref = SmartPointer<T>(casted);
+      this->Updated();
+      if (m_owner) m_owner->Updated();
+    }
+  }
+
+  virtual bool IsCompatible(Object* obj) const override {
+    return dynamic_cast<T*>(obj) != nullptr;
+  }
+
+  virtual const char* GetReferenceTypeName() const override {
+    return typeid(T).name();
+  }
+
+  // Serialization stubs
+  virtual void serialize(Archive::xml_oarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::xml_iarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::text_oarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::text_iarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::hrt_oarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::hrt_iarchive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::log_archive & ar, const unsigned int v) override {}
+  virtual void serialize(Archive::property_register_archive & ar, const unsigned int v) override {}
+
+private:
+  Object* m_owner;
+  std::string m_name;
+  std::string m_units;
+  std::string m_group;
+  SmartPointer<T>& m_ref;
+  bool m_ReadOnly;
+};
+
+} // namespace uLib
+
 namespace uLib {
 namespace Archive {
 
@@ -267,7 +379,20 @@ public:
     }
 
     template<class T> void save_property_impl(const char* name, T& val, const char* units, bool hasRange, const T& minVal, const T& maxVal, bool isReadOnly) {
-        if (m_Object) {
+        if (!m_Object) return;
+        if constexpr (is_smart_pointer<T>::value) {
+            // SmartPointer<U> field: create a ReferenceProperty<U> for type-safe selection
+            using ElementT = typename smart_pointer_element<T>::type;
+            auto* p = new ReferenceProperty<ElementT>(m_Object, name, val, units ? units : "", GetCurrentGroup());
+            p->SetReadOnly(isReadOnly);
+            if (m_DisplayOnly) {
+                m_Object->RegisterDisplayProperty(p);
+                Object* obj = m_Object;
+                Object::connect(p, &Object::Updated, [obj]() { obj->Updated(); });
+            } else {
+                m_Object->RegisterDynamicProperty(p);
+            }
+        } else {
             Property<T>* p = new Property<T>(m_Object, name, &val, units ? units : "", GetCurrentGroup());
             set_range_helper(p, hasRange, minVal, maxVal, typename std::is_arithmetic<T>::type());
             p->SetReadOnly(isReadOnly);

src/HEP/Geant/GeantRegistration.cpp

@@ -12,6 +12,8 @@ ULIB_REGISTER_OBJECT(Material)
 ULIB_REGISTER_OBJECT(Solid)
 ULIB_REGISTER_OBJECT(TessellatedSolid)
 ULIB_REGISTER_OBJECT(BoxSolid)
+ULIB_REGISTER_OBJECT(LogicalVolume)
+ULIB_REGISTER_OBJECT(PhysicalVolume)
 ULIB_REGISTER_OBJECT(Scene)
 ULIB_REGISTER_OBJECT(SkyPlaneEmitterPrimary)
 ULIB_REGISTER_OBJECT(CylinderEmitterPrimary)

src/HEP/Geant/Solid.h

@@ -163,7 +163,7 @@ protected:
 
   G4VPhysicalVolume *m_Physical;
 
-  // ULIB_DECLARE_PROPERTIES(PhysicalVolume)
+  ULIB_DECLARE_PROPERTIES(PhysicalVolume)
 };
 
 
@@ -173,9 +173,11 @@ protected:
 
 
 class TessellatedSolid : public Solid {
-public:
-  uLibTypeMacro(TessellatedSolid, Solid)
 
+  uLibTypeMacro(TessellatedSolid, Solid)
+  ULIB_SERIALIZE_ACCESS
+
+public:
   TessellatedSolid();
   TessellatedSolid(const char *name);
   
@@ -191,6 +193,8 @@ public:
 protected:
   SmartPointer<TriangleMesh> m_Mesh;
   G4TessellatedSolid *m_Solid;
+
+  //ULIB_DECLARE_PROPERTIES(TessellatedSolid)
 };
 
 
@@ -198,8 +202,11 @@ protected:
 //// BOX SOLID /////////////////////////////////////////////////////////////////
 
 class BoxSolid : public Solid {
-public:
+
   uLibTypeMacro(BoxSolid, Solid)
+  ULIB_SERIALIZE_ACCESS
+
+public:  
 
   BoxSolid();
   BoxSolid(const char *name);
@@ -222,6 +229,8 @@ private:
   SmartPointer<ContainerBox> m_ContainerBox;
 
   G4Box *m_Solid;
+  
+  ULIB_DECLARE_PROPERTIES(BoxSolid)
 };