feat: implement MultiSelectionProp to support grouped object transformation and selection in Viewport

app/gcompose/src/MainPanel.cpp

@@ -13,6 +13,7 @@
 #include <QPushButton>
 #include <QMenu>
 #include <QAction>
+#include <QShortcut>
 #include <QApplication>
 #include <QFileDialog>
 #include <QFileInfo>
@@ -104,6 +105,14 @@ MainPanel::MainPanel(QWidget* parent) : QWidget(parent), m_context(nullptr), m_m
     m_rootSplitter->setSizes(sizes);
 
     mainLayout->addWidget(m_rootSplitter, 1);
+    
+    // Shortcuts
+    auto* groupShortcut = new QShortcut(QKeySequence("Ctrl+G"), this);
+    connect(groupShortcut, &QShortcut::activated, [this]() {
+        if (auto* viewport = qobject_cast<uLib::Vtk::QViewport*>(m_firstPane->currentViewport())) {
+            viewport->GroupSelection(m_context);
+        }
+    });
 }
 
 void MainPanel::setContext(uLib::ObjectsContext* context) {

src/Vtk/CMakeLists.txt

@@ -4,6 +4,7 @@ set(HEADERS uLibVtkInterface.h
             vtkQViewport.h
             vtkViewport.h
             vtkObjectsContext.h
+            vtkMultiSelectionProp.h
             )
 
 set(SOURCES uLibVtkInterface.cxx
@@ -12,6 +13,7 @@ set(SOURCES uLibVtkInterface.cxx
             vtkQViewport.cpp
             vtkViewport.cpp
             vtkObjectsContext.cpp
+            vtkMultiSelectionProp.cpp
             )
 
 ## Pull in Math VTK wrappers (sets MATH_SOURCES / MATH_HEADERS)

src/Vtk/vtkMultiSelectionProp.cpp

@@ -0,0 +1,154 @@
+#include "vtkMultiSelectionProp.h"
+#include <vtkActor.h>
+#include <vtkPolyDataMapper.h>
+#include <vtkCubeSource.h>
+#include <vtkProperty.h>
+#include <vtkMatrix4x4.h>
+#include <vtkRenderer.h>
+#include <vtkRendererCollection.h>
+#include "Math/Transform.h"
+#include "Vtk/Math/vtkDense.h"
+
+namespace uLib {
+namespace Vtk {
+
+MultiSelectionProp::MultiSelectionProp() : Prop3D() {
+    this->SetInstanceName("Selection Group");
+    m_PrevMatrix = vtkSmartPointer<vtkMatrix4x4>::New();
+    m_GroupHighlightActor = vtkSmartPointer<vtkActor>::New();
+    
+    vtkNew<vtkPolyDataMapper> mapper;
+    m_GroupHighlightActor->SetMapper(mapper);
+    m_GroupHighlightActor->GetProperty()->SetRepresentationToWireframe();
+    m_GroupHighlightActor->GetProperty()->SetColor(0.0, 1.0, 0.0); // Green for group
+    m_GroupHighlightActor->GetProperty()->SetLineWidth(2.0);
+    m_GroupHighlightActor->GetProperty()->SetLighting(0);
+    m_GroupHighlightActor->PickableOff();
+}
+
+MultiSelectionProp::~MultiSelectionProp() {
+}
+
+MultiSelectionProp* MultiSelectionProp::Clone() const {
+    auto* copy = new MultiSelectionProp();
+    copy->SetMembers(this->m_Members);
+    copy->SetInstanceName(this->GetInstanceName());
+    return copy;
+}
+
+void MultiSelectionProp::SetMembers(const std::vector<Prop3D*>& members) {
+    m_Members = members;
+    Update();
+    
+    // Reset prev matrix to current highlight position
+    if (m_GroupHighlightActor->GetUserMatrix()) {
+        m_PrevMatrix->DeepCopy(m_GroupHighlightActor->GetUserMatrix());
+    } else {
+        m_PrevMatrix->Identity();
+    }
+}
+
+void MultiSelectionProp::Update() {
+    if (m_Members.empty()) {
+        m_GroupHighlightActor->VisibilityOff();
+        return;
+    }
+    m_GroupHighlightActor->VisibilityOn();
+    double combinedBounds[6] = {VTK_DOUBLE_MAX, VTK_DOUBLE_MIN, 
+                                VTK_DOUBLE_MAX, VTK_DOUBLE_MIN, 
+                                VTK_DOUBLE_MAX, VTK_DOUBLE_MIN};
+
+    for (auto* member : m_Members) {
+        if (vtkProp* prop = member->GetProp()) {
+            double* b = prop->GetBounds();
+            if (b) {
+                for (int i = 0; i < 3; ++i) {
+                    if (b[2*i] < combinedBounds[2*i]) combinedBounds[2*i] = b[2*i];
+                    if (b[2*i+1] > combinedBounds[2*i+1]) combinedBounds[2*i+1] = b[2*i+1];
+                }
+            }
+        }
+    }
+
+    if (combinedBounds[0] > combinedBounds[1]) return;
+
+    vtkNew<vtkCubeSource> cube;
+    double maxDim = std::max({combinedBounds[1]-combinedBounds[0], 
+                              combinedBounds[3]-combinedBounds[2], 
+                              combinedBounds[5]-combinedBounds[4]});
+    double pad = maxDim * 0.02;
+    if (pad < 1e-4) pad = 0.05;
+
+    cube->SetBounds(combinedBounds[0]-pad, combinedBounds[1]+pad,
+                    combinedBounds[2]-pad, combinedBounds[3]+pad,
+                    combinedBounds[4]-pad, combinedBounds[5]+pad);
+    cube->Update();
+    
+    if (auto* mapper = vtkPolyDataMapper::SafeDownCast(m_GroupHighlightActor->GetMapper())) {
+        mapper->SetInputConnection(cube->GetOutputPort());
+    }
+
+    // The highlight actor itself should have identity user matrix initially,
+    // as it's defined in world space bounds.
+    m_GroupHighlightActor->SetUserMatrix(nullptr);
+    m_PrevMatrix->Identity();
+
+    // Ensure it's in the renderers
+    vtkRendererCollection* rens = this->GetRenderers();
+    rens->InitTraversal();
+    for (int i = 0; i < rens->GetNumberOfItems(); ++i) {
+        vtkRenderer* ren = rens->GetNextItem();
+        ren->AddActor(m_GroupHighlightActor);
+    }
+}
+
+void MultiSelectionProp::SyncFromVtk() {
+    if (m_Members.empty()) return;
+    
+    vtkMatrix4x4* currentMatrix = m_GroupHighlightActor->GetUserMatrix();
+    if (!currentMatrix) return;
+
+    // Calculate Delta: currentMatrix * Inv(m_PrevMatrix)
+    vtkNew<vtkMatrix4x4> invPrev;
+    vtkMatrix4x4::Invert(m_PrevMatrix, invPrev);
+    
+    vtkNew<vtkMatrix4x4> delta;
+    vtkMatrix4x4::Multiply4x4(currentMatrix, invPrev, delta);
+
+    // Apply delta to all members
+    for (auto* member : m_Members) {
+        if (auto* content = member->GetContent()) {
+            if (auto* tr = dynamic_cast<uLib::TRS*>(content)) {
+                vtkNew<vtkMatrix4x4> memberWorldMatrix;
+                Matrix4fToVtk(tr->GetWorldMatrix(), memberWorldMatrix);
+                
+                vtkNew<vtkMatrix4x4> nextWorldMatrix;
+                vtkMatrix4x4::Multiply4x4(delta, memberWorldMatrix, nextWorldMatrix);
+                
+                // Set the new world matrix.
+                // We need to calculate the new local matrix if there's a parent.
+                if (tr->GetParent()) {
+                    Matrix4f invParentWorld = tr->GetParent()->GetWorldMatrix().inverse();
+                    Matrix4f nextLocalMatrix = invParentWorld * VtkToMatrix4f(nextWorldMatrix);
+                    tr->FromMatrix(nextLocalMatrix);
+                } else {
+                    tr->FromMatrix(VtkToMatrix4f(nextWorldMatrix));
+                }
+                member->Update();
+            }
+        }
+    }
+    
+    m_PrevMatrix->DeepCopy(currentMatrix);
+}
+
+vtkProp* MultiSelectionProp::GetProp() {
+    return m_GroupHighlightActor;
+}
+
+vtkProp3D* MultiSelectionProp::GetProxyProp() {
+    return m_GroupHighlightActor;
+}
+
+} // namespace Vtk
+} // namespace uLib

src/Vtk/vtkMultiSelectionProp.h

@@ -0,0 +1,49 @@
+#ifndef ULIB_VTK_MULTISELECTIONPROP_H
+#define ULIB_VTK_MULTISELECTIONPROP_H
+
+#include "uLibVtkInterface.h"
+#include <vector>
+#include <vtkSmartPointer.h>
+#include <vtkMatrix4x4.h>
+
+class vtkActor;
+class vtkProp;
+class vtkProp3D;
+
+namespace uLib {
+namespace Vtk {
+
+/**
+ * @class MultiSelectionProp
+ * @brief A proxy Prop3D that represents a group of selected Prop3Ds.
+ * It manages a combined highlight and propagates transformations to its members.
+ */
+class MultiSelectionProp : public Prop3D {
+public:
+    uLibTypeMacro(MultiSelectionProp, Prop3D)
+
+    MultiSelectionProp();
+    virtual ~MultiSelectionProp();
+
+    /** @brief Creates a new instance that is a copy of this one's selection state. */
+    MultiSelectionProp* Clone() const;
+
+    void SetMembers(const std::vector<Prop3D*>& members);
+    const std::vector<Prop3D*>& GetMembers() const { return m_Members; }
+
+    virtual void Update() override;
+    virtual void SyncFromVtk() override;
+
+    virtual vtkProp* GetProp() override;
+    virtual vtkProp3D* GetProxyProp() override;
+
+private:
+    std::vector<Prop3D*> m_Members;
+    vtkSmartPointer<vtkMatrix4x4> m_PrevMatrix;
+    vtkSmartPointer<vtkActor> m_GroupHighlightActor;
+};
+
+} // namespace Vtk
+} // namespace uLib
+
+#endif // ULIB_VTK_MULTISELECTIONPROP_H

src/Vtk/vtkObjectsContext.cpp

@@ -136,6 +136,10 @@ Prop3D *ObjectsContext::CreateProp3D(uLib::Object *obj) {
   if (!obj)
     return nullptr;
 
+  if (auto* p3d = dynamic_cast<Prop3D*>(obj)) {
+      return p3d;
+  }
+
   if (auto *vox = dynamic_cast<uLib::Abstract::VoxImage *>(obj)) {
     return new VoxImage(vox);
   } else if (auto *box = dynamic_cast<uLib::ContainerBox *>(obj)) {

src/Vtk/vtkViewport.cpp

@@ -36,6 +36,8 @@
 #include "Vtk/Math/vtkCylinder.h"
 #include "Math/Transform.h"
 #include "Vtk/Math/vtkAssembly.h"
+#include "vtkMultiSelectionProp.h"
+#include <vtkRendererCollection.h>
 
 namespace uLib {
 namespace Vtk {
@@ -69,6 +71,7 @@ struct ViewportData {
 Viewport::Viewport()
     : pv(new ViewportData())
     , m_GridAxis(Y)
+    , m_MultiSelectionProp(new MultiSelectionProp())
 {
 }
 
@@ -100,6 +103,10 @@ Viewport::~Viewport()
         pv->m_CameraWidget->Off();
         pv->m_CameraWidget->SetInteractor(nullptr);
     }
+    if (m_MultiSelectionProp) {
+        delete m_MultiSelectionProp;
+        m_MultiSelectionProp = nullptr;
+    }
     delete pv;
 }
 
@@ -192,6 +199,11 @@ void Viewport::SetupPipeline(vtkRenderWindowInteractor* iren)
         pv->m_Renderer->SetLayer(0);
     }
 
+    // Connect MultiSelectionProp
+    if (m_MultiSelectionProp) {
+        m_MultiSelectionProp->ConnectRenderer(pv->m_Renderer);
+    }
+
     // Setup Handler Widget
     if (!std::getenv("CTEST_PROJECT_NAME")) {
         pv->m_HandlerWidget = vtkSmartPointer<HandlerWidget>::New();
@@ -206,8 +218,10 @@ void Viewport::SetupPipeline(vtkRenderWindowInteractor* iren)
         widgetInteractionCallback->SetClientData(this);
         widgetInteractionCallback->SetCallback([](vtkObject*, unsigned long, void* clientdata, void*){
             auto* self = static_cast<Viewport*>(clientdata);
-            for (auto* p : self->m_Prop3Ds) {
-                if (p->IsSelected()) {
+            if (self->m_SelectedProps.size() > 1 && self->m_MultiSelectionProp) {
+                self->m_MultiSelectionProp->SyncFromVtk();
+            } else {
+                for (auto* p : self->m_SelectedProps) {
                     p->SyncFromVtk();
                 }
             }
@@ -222,6 +236,7 @@ void Viewport::SetupPipeline(vtkRenderWindowInteractor* iren)
     clickCallback->SetCallback([](vtkObject* caller, unsigned long, void* clientdata, void*){
         auto* iren = static_cast<vtkRenderWindowInteractor*>(caller);
         auto* self = static_cast<Viewport*>(clientdata);
+        bool multiSelect = iren->GetShiftKey() != 0;
         
         int* pos = iren->GetEventPosition();
         self->pv->m_Picker->Pick(pos[0], pos[1], 0, self->pv->m_Renderer);
@@ -291,7 +306,7 @@ void Viewport::SetupPipeline(vtkRenderWindowInteractor* iren)
                 }
             }
         }
-        self->SelectProp3D(target);
+        self->SelectProp3D(target, multiSelect);
     });
     iren->AddObserver(vtkCommand::LeftButtonPressEvent, clickCallback);
 
@@ -446,6 +461,11 @@ void Viewport::RegisterProp3D(Prop3D* p, bool isPart) {
     m_Prop3Ds.push_back(p);
     p->ConnectRenderer(pv->m_Renderer);
 
+    // Ensure m_MultiSelectionProp also has the same renderers
+    if (m_MultiSelectionProp) {
+        m_MultiSelectionProp->GetRenderers()->AddItem(pv->m_Renderer);
+    }
+
     // If it's a part of an assembly, we don't want to draw it twice.
     // Assembly itself already draws its parts. 
     // But we need ConnectRenderer above to allow highliting and property updates.
@@ -497,28 +517,59 @@ void Viewport::ObserveContext(ObjectsContext* ctx) {
     });
 }
 
-void Viewport::SelectProp3D(Prop3D* prop)
+void Viewport::SelectProp3D(Prop3D* prop, bool multi)
 {
-    for (auto* p : m_Prop3Ds) {
-        p->SetSelected(p == prop);
-    }
-    
-    if (pv->m_HandlerWidget) {
+    if (multi) {
         if (prop) {
-            vtkProp3D* prop3d = prop->GetProxyProp();
+            auto it = std::find(m_SelectedProps.begin(), m_SelectedProps.end(), prop);
+            if (it != m_SelectedProps.end()) {
+                prop->SetSelected(false);
+                m_SelectedProps.erase(it);
+            } else {
+                prop->SetSelected(true);
+                m_SelectedProps.push_back(prop);
+            }
+        }
+    } else {
+        for (auto* p : m_SelectedProps) {
+            p->SetSelected(false);
+        }
+        m_SelectedProps.clear();
+        if (prop) {
+            prop->SetSelected(true);
+            m_SelectedProps.push_back(prop);
+        }
+    }
+
+    // Update HandlerWidget
+    if (pv->m_HandlerWidget) {
+        if (m_SelectedProps.empty()) {
+            pv->m_HandlerWidget->SetEnabled(0);
+            pv->m_HandlerWidget->SetProp3D(nullptr);
+            if (m_MultiSelectionProp) m_MultiSelectionProp->SetMembers({});
+        } else if (m_SelectedProps.size() == 1) {
+            Prop3D* selected = m_SelectedProps[0];
+            vtkProp3D* prop3d = selected->GetProxyProp();
             if (prop3d) {
                 pv->m_HandlerWidget->SetProp3D(prop3d);
                 pv->m_HandlerWidget->SetEnabled(1);
-                pv->m_HandlerWidget->PlaceWidget(prop3d->GetBounds()); //TODO: FIX !
+                pv->m_HandlerWidget->PlaceWidget(prop3d->GetBounds());
             }
+            if (m_MultiSelectionProp) m_MultiSelectionProp->SetMembers({});
         } else {
-            pv->m_HandlerWidget->SetEnabled(0);
-            pv->m_HandlerWidget->SetProp3D(nullptr);
+            // Multi-selection
+            if (m_MultiSelectionProp) {
+                m_MultiSelectionProp->SetMembers(m_SelectedProps);
+                vtkProp3D* proxy = m_MultiSelectionProp->GetProxyProp();
+                pv->m_HandlerWidget->SetProp3D(proxy);
+                pv->m_HandlerWidget->SetEnabled(1);
+                pv->m_HandlerWidget->PlaceWidget(proxy->GetBounds());
+            }
         }
     }
     
     Render();
-    OnSelectionChanged(prop);
+    OnSelectionChanged(m_SelectedProps.empty() ? nullptr : m_SelectedProps.back());
 }
 
 void Viewport::SetGridVisible(bool visible)
@@ -657,5 +708,19 @@ void Viewport::UpdateGrid()
     pv->m_Annotation->SetText(1, gridLabel);
 }
 
+void Viewport::GroupSelection(uLib::ObjectsContext* targetCtx) {
+    if (!targetCtx || m_SelectedProps.size() <= 1 || !m_MultiSelectionProp) return;
+
+    // Clone the current multi-selection proxy
+    MultiSelectionProp* group = m_MultiSelectionProp->Clone();
+    
+    // Add it to the context
+    targetCtx->AddObject(group);
+    
+    // Select the new group and clear multi-selection
+    m_SelectedProps.clear();
+    SelectProp3D(group);
+}
+
 } // namespace Vtk
 } // namespace uLib

src/Vtk/vtkViewport.h

@@ -29,6 +29,7 @@ namespace Vtk {
 
 struct ViewportData;
 class HandlerWidget;
+class MultiSelectionProp;
 class ObjectsContext;
 
 /**
@@ -49,7 +50,11 @@ public:
     // Prop3D / prop management
     void AddProp3D(Prop3D &prop);
     void RemoveProp3D(Prop3D &prop);
-    void SelectProp3D(Prop3D *prop);
+    /** @brief Selects a specific Prop3D. If multi is true, it toggles selection in a group. */
+    void SelectProp3D(Prop3D* target, bool multi = false);
+
+    /** @brief Creates a persistent Selection Group from the current multi-selection. */
+    void GroupSelection(uLib::ObjectsContext* targetCtx);
     void addProp(vtkProp *prop);
     void RemoveProp(vtkProp *prop);
 
@@ -91,6 +96,8 @@ protected:
     struct ViewportData *pv;
     Axis                                         m_GridAxis;
     std::vector<Prop3D*>                         m_Prop3Ds;
+    std::vector<Prop3D*>                         m_SelectedProps;
+    MultiSelectionProp*                          m_MultiSelectionProp;
     std::map<uLib::Object*, Prop3D*>             m_ObjectToProp3D;
 };