[3d] Tessellator fixes + culling mode configuration for 3D polygons

- missing vertical walls since a recent tessellator crash fix (fixes #17604)
- choice of the culling mode - no culling / back face / front face (fixes #17619)
- more unit tests for tessellator

Author: wonder-sk

src/3d/qgs3dutils.cpp

@@ -82,6 +82,30 @@ AltitudeBinding Qgs3DUtils::altBindingFromString( const QString &str )
     return AltBindCentroid;
 }
 
+QString Qgs3DUtils::cullingModeToString( Qt3DRender::QCullFace::CullingMode mode )
+{
+  switch ( mode )
+  {
+    case Qt3DRender::QCullFace::NoCulling: return QStringLiteral( "no-culling" );
+    case Qt3DRender::QCullFace::Front: return QStringLiteral( "front" );
+    case Qt3DRender::QCullFace::Back: return QStringLiteral( "back" );
+    case Qt3DRender::QCullFace::FrontAndBack: return QStringLiteral( "front-and-back" );
+    default: return QString();
+  }
+}
+
+Qt3DRender::QCullFace::CullingMode Qgs3DUtils::cullingModeFromString( const QString &str )
+{
+  if ( str == QStringLiteral( "front" ) )
+    return Qt3DRender::QCullFace::Front;
+  else if ( str == QStringLiteral( "back" ) )
+    return Qt3DRender::QCullFace::Back;
+  else if ( str == QStringLiteral( "front-and-back" ) )
+    return Qt3DRender::QCullFace::FrontAndBack;
+  else
+    return Qt3DRender::QCullFace::NoCulling;
+}
+
 
 void Qgs3DUtils::clampAltitudes( QgsLineString *lineString, AltitudeClamping altClamp, AltitudeBinding altBind, const QgsPoint &centroid, float height, const Qgs3DMapSettings &map )
 {

src/3d/qgs3dutils.h

@@ -22,6 +22,8 @@ class QgsPolygon;
 #include "qgs3dmapsettings.h"
 #include "qgsaabb.h"
 
+#include <Qt3DRender/QCullFace>
+
 //! how to handle altitude of vector features
 enum AltitudeClamping
 {
@@ -64,6 +66,11 @@ class _3D_EXPORT Qgs3DUtils
     //! Converts a string to a value from AltitudeBinding enum
     static AltitudeBinding altBindingFromString( const QString &str );
 
+    //! Converts a value from CullingMode enum to a string
+    static QString cullingModeToString( Qt3DRender::QCullFace::CullingMode mode );
+    //! Converts a string to a value from CullingMode enum
+    static Qt3DRender::QCullFace::CullingMode cullingModeFromString( const QString &str );
+
     //! Clamps altitude of vertices of a linestring according to the settings
     static void clampAltitudes( QgsLineString *lineString, AltitudeClamping altClamp, AltitudeBinding altBind, const QgsPoint &centroid, float height, const Qgs3DMapSettings &map );
     //! Clamps altitude of vertices of a polygon according to the settings

src/3d/qgstessellatedpolygongeometry.cpp

@@ -58,14 +58,10 @@ QgsTessellatedPolygonGeometry::QgsTessellatedPolygonGeometry( QNode *parent )
 
 QgsTessellatedPolygonGeometry::~QgsTessellatedPolygonGeometry()
 {
-  qDeleteAll( mPolygons );
 }
 
 void QgsTessellatedPolygonGeometry::setPolygons( const QList<QgsPolygon *> &polygons, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon )
 {
-  qDeleteAll( mPolygons );
-  mPolygons = polygons;
-
   QgsTessellator tessellator( origin.x(), origin.y(), mWithNormals );
   for ( int i = 0; i < polygons.count(); ++i )
   {
@@ -74,6 +70,8 @@ void QgsTessellatedPolygonGeometry::setPolygons( const QList<QgsPolygon *> &poly
     tessellator.addPolygon( *polygon, extr );
   }
 
+  qDeleteAll( polygons );
+
   QByteArray data( ( const char * )tessellator.data().constData(), tessellator.data().count() * sizeof( float ) );
   int nVerts = data.count() / tessellator.stride();
 

src/3d/qgstessellatedpolygongeometry.h

@@ -45,7 +45,6 @@ class QgsTessellatedPolygonGeometry : public Qt3DRender::QGeometry
     void setPolygons( const QList<QgsPolygon *> &polygons, const QgsPointXY &origin, float extrusionHeight, const QList<float> &extrusionHeightPerPolygon = QList<float>() );
 
   private:
-    QList<QgsPolygon *> mPolygons;
 
     Qt3DRender::QAttribute *mPositionAttribute = nullptr;
     Qt3DRender::QAttribute *mNormalAttribute = nullptr;