MaliputViewerPlugin: Provides ray-cast support

delphyne_gui/visualizer/layout2_maliput_viewer.config

@@ -79,6 +79,7 @@
 
 <plugin filename="Scene3D">
   <ignition-gui>
+    <title>Main3DScene</title>
     <property type="bool" key="showTitleBar">false</property>
     <property type="bool" key="showCollapseButton">false</property>
     <property type="bool" key="showDockButton">false</property>

delphyne_gui/visualizer/maliput_viewer_plugin.cc

@@ -3,6 +3,7 @@
 #include "maliput_viewer_plugin.hh"
 
 #include <ignition/common/Console.hh>
+#include <ignition/gui/Conversions.hh>
 #include <ignition/plugin/Register.hh>
 #include <ignition/rendering/RenderEngine.hh>
 #include <ignition/rendering/RenderingIface.hh>
@@ -125,7 +126,7 @@ void MaliputViewerPlugin::timerEvent(QTimerEvent* _event) {
     return;
   }
   timer.stop();
-  ConfigurateScene();
+  Initialize();
   RenderMeshes();
 }
 
@@ -316,16 +317,22 @@ void MaliputViewerPlugin::LoadConfig(const tinyxml2::XMLElement* _pluginElem) {
     timer.start(kTimerPeriodInMs, this);
     return;
   }
-  ConfigurateScene();
+  Initialize();
   RenderMeshes();
 }
 
-void MaliputViewerPlugin::ConfigurateScene() {
+void MaliputViewerPlugin::Initialize() {
+  rayQuery = scene->CreateRayQuery();
   rootVisual = scene->RootVisual();
   if (!rootVisual) {
     ignerr << "Failed to find the root visual" << std::endl;
     return;
   }
+  camera = std::dynamic_pointer_cast<ignition::rendering::Camera>(rootVisual->ChildByIndex(0));
+  if (!camera) {
+    ignerr << "Failed to find the camera" << std::endl;
+    return;
+  }
   // Lights.
   const double lightRed = 0.88;
   const double lightGreen = 0.88;
@@ -340,6 +347,58 @@ void MaliputViewerPlugin::ConfigurateScene() {
   directionalLight->SetDiffuseColor(lightRed, lightGreen, lightBlue);
   directionalLight->SetSpecularColor(lightRed, lightGreen, lightBlue);
   rootVisual->AddChild(directionalLight);
+
+  // Install event filter to get mouse event from the main scene.
+  QList<Plugin*> plugins = parent()->findChildren<Plugin*>();
+  Plugin* scene3D{nullptr};
+  for (auto& plugin : plugins) {
+    if (plugin->Title() == kMainScene3dPlugin) {
+      scene3D = plugin;
+      break;
+    }
+  }
+  if (!scene3D) {
+    ignerr << "Scene3D plugin titled '" << kMainScene3dPlugin << "' wasn't found. MouseEvents won't be filtered."
+           << std::endl;
+  } else {
+    auto renderWindowItem = scene3D->PluginItem()->findChild<QQuickItem*>();
+    renderWindowItem->installEventFilter(this);
+  }
+}
+
+bool MaliputViewerPlugin::eventFilter(QObject* _obj, QEvent* _event) {
+  if (_event->type() == QEvent::Type::MouseButtonPress) {
+    QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(_event);
+    if (mouseEvent && mouseEvent->button() == Qt::LeftButton) {
+      MouseClickHandler(mouseEvent);
+    }
+  }
+  // Standard event processing
+  return QObject::eventFilter(_obj, _event);
+}
+
+void MaliputViewerPlugin::MouseClickHandler(QMouseEvent* _mouseEvent) {
+  const auto rayQueryResult = ScreenToScene(_mouseEvent->x(), _mouseEvent->y());
+  if (rayQueryResult.distance > -1) {
+    const maliput::api::Lane* lane = model->GetLaneFromWorldPosition(rayQueryResult.point);
+    if (lane) {
+      const std::string& lane_id = lane->id().string();
+      ignmsg << "Clicked lane ID: " << lane_id << std::endl;
+    }
+  }
+}
+
+ignition::rendering::RayQueryResult MaliputViewerPlugin::ScreenToScene(int screenX, int screenY) const {
+  // Normalize point on the image
+  const double width = camera->ImageWidth();
+  const double height = camera->ImageHeight();
+
+  const double nx = 2.0 * screenX / width - 1.0;
+  const double ny = 1.0 - 2.0 * screenY / height;
+
+  // Make a ray query
+  rayQuery->SetFromCamera(camera, {nx, ny});
+  return rayQuery->ClosestPoint();
 }
 
 }  // namespace gui

delphyne_gui/visualizer/maliput_viewer_plugin.hh

@@ -6,7 +6,9 @@
 
 #include <maliput/api/road_geometry.h>
 
+#include <ignition/common/MouseEvent.hh>
 #include <ignition/gui/Plugin.hh>
+#include <ignition/rendering/RayQuery.hh>
 #include <ignition/rendering/RenderTypes.hh>
 #include <ignition/rendering/Scene.hh>
 
@@ -52,10 +54,16 @@ class MaliputViewerPlugin : public ignition::gui::Plugin {
   void LabelCheckboxesChanged();
 
  protected:
-  /// @brief Timer event callback which handles the logic to load the meshes when
+  /// \brief Timer event callback which handles the logic to load the meshes when
   ///        the scene is not ready yet.
   void timerEvent(QTimerEvent* _event) override;
 
+  /// \brief Intercepts an @p _event delivered to other object @p _obj.
+  /// \details We are particularly interested in QMouseEvents happening within the main scene.
+  ///          This method is called automatically by the QT Event System iff the event filter was installed
+  ///          in the target object. \see QObject::installEventFilter method.
+  bool eventFilter(QObject* _obj, QEvent* _event) override;
+
  protected slots:
   /// \brief Clears the visualizer, loads a RoadNetwork and update the GUI with meshes and labels.
   /// \param[in] _mapFile The path to the map file to load and visualize.
@@ -82,6 +90,9 @@ class MaliputViewerPlugin : public ignition::gui::Plugin {
   /// @brief The scene name.
   static constexpr char const* kSceneName = "scene";
 
+  /// @brief The Scene3D instance holding the main scene.
+  static constexpr char const* kMainScene3dPlugin = "Main3DScene";
+
   /// @brief The rendering engine name.
   static constexpr char const* kEngineName = "ogre";
 
@@ -104,6 +115,16 @@ class MaliputViewerPlugin : public ignition::gui::Plugin {
   /// \brief Renders meshes for the road and the labels.
   void RenderMeshes();
 
+  /// \brief Handles the left click mouse event.
+  /// @param[in] _mouseEvent QMouseEvent pointer.
+  void MouseClickHandler(QMouseEvent* _mouseEvent);
+
+  /// \brief Performs a raycast on the screen.
+  /// \param[in] screenX X screen's coordinate.
+  /// \param[in] screenY Y screen's coordinate.
+  /// \return A ignition::rendering::RayQueryResult.
+  ignition::rendering::RayQueryResult ScreenToScene(int screenX, int screenY) const;
+
   /// \brief Builds visuals for each mesh inside @p _maliputMeshes that is
   /// enabled.
   /// \param[in] _maliputMeshes A map of meshes to render.
@@ -116,8 +137,10 @@ class MaliputViewerPlugin : public ignition::gui::Plugin {
   /// \brief Clears all the references to text labels, meshes and the scene.
   void Clear();
 
-  /// \brief Configurate scene.
-  void ConfigurateScene();
+  /// \brief Configurate scene and install event filter for filtering QMouseEvents.
+  /// \details To install the event filter the Scene3D plugin hosting the scene
+  ///          is expected to be titled as #kMainScene3dPlugin.
+  void Initialize();
 
   /// \brief Holds the map file path.
   std::string mapFile{""};
@@ -146,6 +169,12 @@ class MaliputViewerPlugin : public ignition::gui::Plugin {
   /// \brief Holds a pointer to the scene.
   ignition::rendering::ScenePtr scene{nullptr};
 
+  /// \brief Holds a pointer to a ray query.
+  ignition::rendering::RayQueryPtr rayQuery{nullptr};
+
+  /// \brief Holds a pointer to the camera.
+  ignition::rendering::CameraPtr camera{};
+
   /// \brief Model that holds the meshes and the visualization status.
   std::unique_ptr<MaliputViewerModel> model{};
 };