[FEATURE] 3D identify tool working on 3D entities

Until now the tool only considered terrain. This commit adds support
for 3D renderers created from vector layers, so it is possible to
correctly identify polygons and linestrings in 3D.

Author: wonder-sk

python/gui/auto_generated/qgsmaptoolidentify.sip.in

@@ -158,6 +158,11 @@ Call the right method depending on layer type
     bool identifyRasterLayer( QList<QgsMapToolIdentify::IdentifyResult> *results, QgsRasterLayer *layer, QgsPointXY point, const QgsRectangle &viewExtent, double mapUnitsPerPixel );
     bool identifyVectorLayer( QList<QgsMapToolIdentify::IdentifyResult> *results, QgsVectorLayer *layer, const QgsPointXY &point );
 
+    QMap< QString, QString > derivedAttributesForPoint( const QgsPoint &point );
+%Docstring
+Returns derived attributes map for a clicked point in map coordinates. May be 2D or 3D point.
+%End
+
 };
 
 QFlags<QgsMapToolIdentify::Type> operator|(QgsMapToolIdentify::Type f1, QFlags<QgsMapToolIdentify::Type> f2);

src/3d/CMakeLists.txt

@@ -56,6 +56,7 @@ SET(QGIS_3D_MOC_HDRS
   qgscameracontroller.h
   qgslayoutitem3dmap.h
   qgsoffscreen3dengine.h
+  qgstessellatedpolygongeometry.h
   qgswindow3dengine.h
 
   chunks/qgschunkedentity_p.h

src/3d/qgs3dmapscene.cpp

@@ -30,6 +30,7 @@
 
 #include "qgsaabb.h"
 #include "qgsabstract3dengine.h"
+#include "qgs3dmapscenepickhandler.h"
 #include "qgs3dmapsettings.h"
 #include "qgs3dutils.h"
 #include "qgsabstract3drenderer.h"
@@ -38,6 +39,7 @@
 #include "qgschunknode_p.h"
 #include "qgsterrainentity_p.h"
 #include "qgsterraingenerator.h"
+#include "qgstessellatedpolygongeometry.h"
 #include "qgsvectorlayer.h"
 #include "qgsvectorlayer3drenderer.h"
 
@@ -177,6 +179,37 @@ int Qgs3DMapScene::terrainPendingJobsCount() const
   return mTerrain ? mTerrain->pendingJobsCount() : 0;
 }
 
+void Qgs3DMapScene::registerPickHandler( Qgs3DMapScenePickHandler *pickHandler )
+{
+  if ( mPickHandlers.isEmpty() )
+  {
+    // we need to add object pickers
+    for ( Qt3DCore::QEntity *entity : mLayerEntities.values() )
+    {
+      Qt3DRender::QObjectPicker *picker = new Qt3DRender::QObjectPicker( entity );
+      entity->addComponent( picker );
+      connect( picker, &Qt3DRender::QObjectPicker::pressed, this, &Qgs3DMapScene::onLayerEntityPickEvent );
+    }
+  }
+
+  mPickHandlers.append( pickHandler );
+}
+
+void Qgs3DMapScene::unregisterPickHandler( Qgs3DMapScenePickHandler *pickHandler )
+{
+  mPickHandlers.removeOne( pickHandler );
+
+  if ( mPickHandlers.isEmpty() )
+  {
+    // we need to remove pickers
+    for ( Qt3DCore::QEntity *entity : mLayerEntities.values() )
+    {
+      Qt3DRender::QObjectPicker *picker = entity->findChild<Qt3DRender::QObjectPicker *>();
+      picker->deleteLater();
+    }
+  }
+}
+
 QgsChunkedEntity::SceneState _sceneState( QgsCameraController *cameraController )
 {
   Qt3DRender::QCamera *camera = cameraController->camera();
@@ -365,6 +398,54 @@ void Qgs3DMapScene::onBackgroundColorChanged()
   mEngine->setClearColor( mMap.backgroundColor() );
 }
 
+void Qgs3DMapScene::onLayerEntityPickEvent( Qt3DRender::QPickEvent *event )
+{
+  if ( event->button() != Qt3DRender::QPickEvent::LeftButton )
+    return;
+
+  Qt3DRender::QPickTriangleEvent *triangleEvent = qobject_cast<Qt3DRender::QPickTriangleEvent *>( event );
+  if ( !triangleEvent )
+    return;
+
+  Qt3DRender::QObjectPicker *picker = qobject_cast<Qt3DRender::QObjectPicker *>( sender() );
+  if ( !picker )
+    return;
+
+  Qt3DCore::QEntity *entity = qobject_cast<Qt3DCore::QEntity *>( picker->parent() );
+  if ( !entity )
+    return;
+
+  QgsMapLayer *layer = mLayerEntities.key( entity );
+  if ( !layer )
+    return;
+
+  QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( layer );
+  if ( !vlayer )
+    return;
+
+  for ( Qgs3DMapScenePickHandler *pickHandler : qgis::as_const( mPickHandlers ) )
+  {
+    // go figure out feature ID from the triangle index
+    QgsFeatureId fid = -1;
+    for ( Qt3DRender::QGeometryRenderer *geomRenderer : entity->findChildren<Qt3DRender::QGeometryRenderer *>() )
+    {
+      // unfortunately we can't access which sub-entity triggered the pick event
+      // so as a temporary workaround let's just ignore the entity with selection
+      // and hope the event was the main entity (QTBUG-58206)
+      if ( geomRenderer->objectName() != "main" )
+        continue;
+
+      if ( QgsTessellatedPolygonGeometry *g = qobject_cast<QgsTessellatedPolygonGeometry *>( geomRenderer->geometry() ) )
+      {
+        fid = g->triangleIndexToFeatureId( triangleEvent->triangleIndex() );
+        break;
+      }
+    }
+    pickHandler->handlePickOnVectorLayer( vlayer, fid, event->worldIntersection() );
+  }
+
+}
+
 void Qgs3DMapScene::onLayerRenderer3DChanged()
 {
   QgsMapLayer *layer = qobject_cast<QgsMapLayer *>( sender() );
@@ -425,6 +506,13 @@ void Qgs3DMapScene::addLayerEntity( QgsMapLayer *layer )
     {
       newEntity->setParent( this );
       mLayerEntities.insert( layer, newEntity );
+
+      if ( !mPickHandlers.isEmpty() )
+      {
+        Qt3DRender::QObjectPicker *picker = new Qt3DRender::QObjectPicker( newEntity );
+        newEntity->addComponent( picker );
+        connect( picker, &Qt3DRender::QObjectPicker::pressed, this, &Qgs3DMapScene::onLayerEntityPickEvent );
+      }
     }
   }
 

src/3d/qgs3dmapscene.h

@@ -24,6 +24,7 @@ namespace Qt3DRender
 {
   class QRenderSettings;
   class QCamera;
+  class QPickEvent;
 }
 
 namespace Qt3DLogic
@@ -39,6 +40,7 @@ namespace Qt3DExtras
 class QgsAbstract3DEngine;
 class QgsMapLayer;
 class QgsCameraController;
+class Qgs3DMapScenePickHandler;
 class Qgs3DMapSettings;
 class QgsTerrainEntity;
 class QgsChunkedEntity;
@@ -76,6 +78,11 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
     //! Returns the current state of the scene
     SceneState sceneState() const { return mSceneState; }
 
+    //! Registers an object that will get results of pick events on 3D entities. Does not take ownerhip of the pick handler. Adds object picker components to 3D entities.
+    void registerPickHandler( Qgs3DMapScenePickHandler *pickHandler );
+    //! Unregisters previously registered pick handler. Pick handler is not deleted. Also removes object picker components from 3D entities.
+    void unregisterPickHandler( Qgs3DMapScenePickHandler *pickHandler );
+
   signals:
     //! Emitted when the current terrain entity is replaced by a new one
     void terrainEntityChanged();
@@ -92,6 +99,7 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
     void onLayersChanged();
     void createTerrainDeferred();
     void onBackgroundColorChanged();
+    void onLayerEntityPickEvent( Qt3DRender::QPickEvent *event );
 
   private:
     void addLayerEntity( QgsMapLayer *layer );
@@ -116,6 +124,8 @@ class _3D_EXPORT Qgs3DMapScene : public Qt3DCore::QEntity
     QMap<QgsMapLayer *, Qt3DCore::QEntity *> mLayerEntities;
     bool mTerrainUpdateScheduled = false;
     SceneState mSceneState = Ready;
+    //! List of currently registered pick handlers (used by identify tool)
+    QList<Qgs3DMapScenePickHandler *> mPickHandlers;
 };
 
 #endif // QGS3DMAPSCENE_H

src/3d/qgs3dmapscenepickhandler.h

@@ -0,0 +1,28 @@
+#ifndef QGS3DMAPSCENEPICKHANDLER_H
+#define QGS3DMAPSCENEPICKHANDLER_H
+
+#include "qgsfeatureid.h"
+
+class QVector3D;
+class QgsVectorLayer;
+
+/**
+ * \ingroup 3d
+ * Abstract base class for handlers that process pick events from a 3D map scene.
+ * 3D entities in map scene get QObjectPicker components assigned and mouse press events trigger virtual methods
+ * or pick handlers.
+ *
+ * This is used for identify tool to be able to identify entities coming from 3D renderers assigned to map layers.
+ *
+ * \since QGIS 3.4
+ */
+class Qgs3DMapScenePickHandler
+{
+  public:
+    virtual ~Qgs3DMapScenePickHandler() {}
+
+    //! Called when user clicked a 3D entity belonging to a feature of a vector layer
+    virtual void handlePickOnVectorLayer( QgsVectorLayer *vlayer, QgsFeatureId id, const QVector3D &worldIntersection ) = 0;
+};
+
+#endif // QGS3DMAPSCENEPICKHANDLER_H

src/3d/qgstessellatedpolygongeometry.cpp

@@ -56,11 +56,20 @@ QgsTessellatedPolygonGeometry::QgsTessellatedPolygonGeometry( QNode *parent )
   }
 }
 
-void QgsTessellatedPolygonGeometry::setPolygons( const QList<QgsPolygon *> &polygons, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon )
+void QgsTessellatedPolygonGeometry::setPolygons( const QList<QgsPolygon *> &polygons, const QList<QgsFeatureId> &featureIds, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon )
 {
+  Q_ASSERT( polygons.count() == featureIds.count() );
+  mTriangleIndexStartingIndices.reserve( polygons.count() );
+  mTriangleIndexFids.reserve( polygons.count() );
+
   QgsTessellator tessellator( origin.x(), origin.y(), mWithNormals, mInvertNormals, mAddBackFaces );
   for ( int i = 0; i < polygons.count(); ++i )
   {
+    Q_ASSERT( tessellator.dataVerticesCount() % 3 == 0 );
+    uint startingTriangleIndex = static_cast<uint>( tessellator.dataVerticesCount() / 3 );
+    mTriangleIndexStartingIndices.append( startingTriangleIndex );
+    mTriangleIndexFids.append( featureIds[i] );
+
     QgsPolygon *polygon = polygons.at( i );
     float extr = extrusionHeightPerPolygon.isEmpty() ? extrusionHeight : extrusionHeightPerPolygon.at( i );
     tessellator.addPolygon( *polygon, extr );
@@ -76,3 +85,38 @@ void QgsTessellatedPolygonGeometry::setPolygons( const QList<QgsPolygon *> &poly
   if ( mNormalAttribute )
     mNormalAttribute->setCount( nVerts );
 }
+
+
+// run binary search on a sorted array, return index i where data[i] <= x < data[i+1]
+static int binary_search( uint v, const uint *data, int count )
+{
+  int idx0 = 0;
+  int idx1 = count - 1;
+
+  if ( v < data[0] )
+    return -1;  // not in the array
+
+  while ( idx0 != idx1 )
+  {
+    int idxPivot = ( idx0 + idx1 ) / 2;
+    uint pivot = data[idxPivot];
+    if ( pivot <= v )
+    {
+      if ( data[idxPivot + 1] > v )
+        return idxPivot;   // we're done!
+      else  // continue searching values greater than the pivot
+        idx0 = idxPivot;
+    }
+    else   // continue searching values lower than the pivot
+      idx1 = idxPivot;
+  }
+  return idx0;
+}
+
+
+QgsFeatureId QgsTessellatedPolygonGeometry::triangleIndexToFeatureId( uint triangleIndex )
+{
+  int i = binary_search( triangleIndex, mTriangleIndexStartingIndices.constData(), mTriangleIndexStartingIndices.count() );
+  Q_ASSERT( i != -1 );
+  return mTriangleIndexFids[i];
+}

src/3d/qgstessellatedpolygongeometry.h

@@ -16,6 +16,7 @@
 #ifndef QGSTESSELLATEDPOLYGONGEOMETRY_H
 #define QGSTESSELLATEDPOLYGONGEOMETRY_H
 
+#include "qgsfeatureid.h"
 #include "qgspolygon.h"
 
 #include <Qt3DRender/QGeometry>
@@ -36,6 +37,7 @@ namespace Qt3DRender
  */
 class QgsTessellatedPolygonGeometry : public Qt3DRender::QGeometry
 {
+    Q_OBJECT
   public:
     //! Constructor
     QgsTessellatedPolygonGeometry( QNode *parent = nullptr );
@@ -58,14 +60,20 @@ class QgsTessellatedPolygonGeometry : public Qt3DRender::QGeometry
     void setAddBackFaces( bool add ) { mAddBackFaces = add; }
 
     //! Initializes vertex buffer from given polygons. Takes ownership of passed polygon geometries
-    void setPolygons( const QList<QgsPolygon *> &polygons, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon = QList<float>() );
+    void setPolygons( const QList<QgsPolygon *> &polygons, const QList<QgsFeatureId> &featureIds, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon = QList<float>() );
+
+    //! Returns ID of the feature to which given triangle index belongs (used for picking)
+    QgsFeatureId triangleIndexToFeatureId( uint triangleIndex );
 
   private:
 
     Qt3DRender::QAttribute *mPositionAttribute = nullptr;
     Qt3DRender::QAttribute *mNormalAttribute = nullptr;
     Qt3DRender::QBuffer *mVertexBuffer = nullptr;
 
+    QVector<QgsFeatureId> mTriangleIndexFids;
+    QVector<uint> mTriangleIndexStartingIndices;
+
     bool mWithNormals = true;
     bool mInvertNormals = false;
     bool mAddBackFaces = false;

src/3d/symbols/qgsline3dsymbol_p.cpp

@@ -85,6 +85,7 @@ void QgsLine3DSymbolEntity::addEntityForNotSelectedLines( const Qgs3DMapSettings
 
   // build the entity
   QgsLine3DSymbolEntityNode *entity = new QgsLine3DSymbolEntityNode( map, layer, symbol, req );
+  entity->findChild<Qt3DRender::QGeometryRenderer *>()->setObjectName( "main" ); // temporary measure to distinguish between "selected" and "main"
   entity->addComponent( mat );
   entity->setParent( this );
 }
@@ -106,6 +107,7 @@ Qt3DRender::QGeometryRenderer *QgsLine3DSymbolEntityNode::renderer( const Qgs3DM
   double mitreLimit = 0;
 
   QList<QgsPolygon *> polygons;
+  QList<QgsFeatureId> fids;
   QgsFeature f;
   QgsFeatureIterator fi = layer->getFeatures( request );
   while ( fi.nextFeature( f ) )
@@ -129,6 +131,7 @@ Qt3DRender::QGeometryRenderer *QgsLine3DSymbolEntityNode::renderer( const Qgs3DM
       QgsPolygon *polyBuffered = static_cast<QgsPolygon *>( buffered );
       Qgs3DUtils::clampAltitudes( polyBuffered, symbol.altitudeClamping(), symbol.altitudeBinding(), symbol.height(), map );
       polygons.append( polyBuffered );
+      fids.append( f.id() );
     }
     else if ( QgsWkbTypes::flatType( buffered->wkbType() ) == QgsWkbTypes::MultiPolygon )
     {
@@ -140,13 +143,14 @@ Qt3DRender::QGeometryRenderer *QgsLine3DSymbolEntityNode::renderer( const Qgs3DM
         QgsPolygon *polyBuffered = static_cast<QgsPolygon *>( partBuffered )->clone(); // need to clone individual geometry parts
         Qgs3DUtils::clampAltitudes( polyBuffered, symbol.altitudeClamping(), symbol.altitudeBinding(), symbol.height(), map );
         polygons.append( polyBuffered );
+        fids.append( f.id() );
       }
       delete buffered;
     }
   }
 
   mGeometry = new QgsTessellatedPolygonGeometry;
-  mGeometry->setPolygons( polygons, origin, symbol.extrusionHeight() );
+  mGeometry->setPolygons( polygons, fids, origin, symbol.extrusionHeight() );
 
   Qt3DRender::QGeometryRenderer *renderer = new Qt3DRender::QGeometryRenderer;
   renderer->setGeometry( mGeometry );

src/3d/symbols/qgspolygon3dsymbol_p.cpp

@@ -101,6 +101,7 @@ void QgsPolygon3DSymbolEntity::addEntityForNotSelectedPolygons( const Qgs3DMapSe
 
   // build the entity
   QgsPolygon3DSymbolEntityNode *entity = new QgsPolygon3DSymbolEntityNode( map, layer, symbol, req );
+  entity->findChild<Qt3DRender::QGeometryRenderer *>()->setObjectName( "main" ); // temporary measure to distinguish between "selected" and "main"
   entity->addComponent( mat );
   entity->addComponent( tform );
   entity->setParent( this );
@@ -141,6 +142,7 @@ Qt3DRender::QGeometryRenderer *QgsPolygon3DSymbolEntityNode::renderer( const Qgs
 {
   QgsPointXY origin( map.origin().x(), map.origin().y() );
   QList<QgsPolygon *> polygons;
+  QList<QgsFeatureId> fids;
   QList<float> extrusionHeightPerPolygon;  // will stay empty if not needed per polygon
 
   QgsExpressionContext ctx( _expressionContext3D() );
@@ -178,6 +180,7 @@ Qt3DRender::QGeometryRenderer *QgsPolygon3DSymbolEntityNode::renderer( const Qgs
       QgsPolygon *polyClone = poly->clone();
       Qgs3DUtils::clampAltitudes( polyClone, symbol.altitudeClamping(), symbol.altitudeBinding(), height, map );
       polygons.append( polyClone );
+      fids.append( f.id() );
       if ( hasDDExtrusion )
         extrusionHeightPerPolygon.append( extrusionHeight );
     }
@@ -190,6 +193,7 @@ Qt3DRender::QGeometryRenderer *QgsPolygon3DSymbolEntityNode::renderer( const Qgs
         QgsPolygon *polyClone = static_cast< const QgsPolygon *>( g2 )->clone();
         Qgs3DUtils::clampAltitudes( polyClone, symbol.altitudeClamping(), symbol.altitudeBinding(), height, map );
         polygons.append( polyClone );
+        fids.append( f.id() );
         if ( hasDDExtrusion )
           extrusionHeightPerPolygon.append( extrusionHeight );
       }
@@ -201,7 +205,7 @@ Qt3DRender::QGeometryRenderer *QgsPolygon3DSymbolEntityNode::renderer( const Qgs
   mGeometry = new QgsTessellatedPolygonGeometry;
   mGeometry->setInvertNormals( symbol.invertNormals() );
   mGeometry->setAddBackFaces( symbol.addBackFaces() );
-  mGeometry->setPolygons( polygons, origin, symbol.extrusionHeight(), extrusionHeightPerPolygon );
+  mGeometry->setPolygons( polygons, fids, origin, symbol.extrusionHeight(), extrusionHeightPerPolygon );
 
   Qt3DRender::QGeometryRenderer *renderer = new Qt3DRender::QGeometryRenderer;
   renderer->setGeometry( mGeometry );