Don't transform z coordinates by default

Since z coordinates can represent potentially any height
unit and reference point, it's not safe to assume that they
always represent height in metres relative to the ellipsoid.

Instead, leave z values untouched by default with geometry
transforms, and make transforming z an optional parameter

Refs #14702

python/core/geometry/qgsabstractgeometryv2.sip

@@ -203,9 +203,15 @@ class QgsAbstractGeometryV2
 
     /** Transforms the geometry using a coordinate transform
      * @param ct coordinate transform
-       @param d transformation direction
-     */
-    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) = 0;
+     * @param d transformation direction
+     * @param transformZ set to true to also transform z coordinates. This requires that
+     * the z coordinates in the geometry represent height relative to the vertical datum
+     * of the source CRS (generally ellipsoidal heights) and are expressed in its vertical
+     * units (generally metres). If false, then z coordinates will not be changed by the
+     * transform.
+     */
+    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                            bool transformZ = false ) = 0;
 
     /** Transforms the geometry using a QTransform object
      * @param t QTransform transformation

python/core/geometry/qgscircularstringv2.sip

@@ -61,12 +61,8 @@ class QgsCircularStringV2: public QgsCurveV2
     virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const;
 
     void draw( QPainter& p ) const;
-
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
     void addToPainterPath( QPainterPath& path ) const;
 

python/core/geometry/qgscompoundcurvev2.sip

@@ -62,11 +62,8 @@ class QgsCompoundCurveV2: public QgsCurveV2
     void addVertex( const QgsPointV2& pt );
 
     void draw( QPainter& p ) const;
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-       @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
     void addToPainterPath( QPainterPath& path ) const;
     void drawAsPolygon( QPainter& p ) const;

python/core/geometry/qgscurvepolygonv2.sip

@@ -57,11 +57,8 @@ class QgsCurvePolygonV2: public QgsSurfaceV2
     bool removeInteriorRing( int nr );
 
     virtual void draw( QPainter& p ) const;
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
 
     virtual bool insertVertex( QgsVertexId position, const QgsPointV2& vertex );

python/core/geometry/qgsgeometrycollectionv2.sip

@@ -46,11 +46,8 @@ class QgsGeometryCollectionV2: public QgsAbstractGeometryV2
      */
     virtual bool removeGeometry( int nr );
 
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
 
     //virtual void clip( const QgsRectangle& rect );

python/core/geometry/qgslinestringv2.sip

@@ -141,8 +141,8 @@ class QgsLineStringV2: public QgsCurveV2
     void points( QList<QgsPointV2>& pt ) const;
 
     void draw( QPainter& p ) const;
-
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
 
     void addToPainterPath( QPainterPath& path ) const;

python/core/geometry/qgspointv2.sip

@@ -153,7 +153,8 @@ class QgsPointV2: public QgsAbstractGeometryV2
     QDomElement asGML3( QDomDocument& doc, int precision = 17, const QString& ns = "gml" ) const;
     QString asJSON( int precision = 17 ) const;
     void draw( QPainter& p ) const;
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform );
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false );
     void transform( const QTransform& t );
     virtual QList< QList< QList< QgsPointV2 > > > coordinateSequence() const;
 

src/core/geometry/qgsabstractgeometryv2.h

@@ -187,9 +187,15 @@ class CORE_EXPORT QgsAbstractGeometryV2
 
     /** Transforms the geometry using a coordinate transform
      * @param ct coordinate transform
-       @param d transformation direction
-     */
-    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) = 0;
+     * @param d transformation direction
+     * @param transformZ set to true to also transform z coordinates. This requires that
+     * the z coordinates in the geometry represent height relative to the vertical datum
+     * of the source CRS (generally ellipsoidal heights) and are expressed in its vertical
+     * units (generally metres). If false, then z coordinates will not be changed by the
+     * transform.
+     */
+    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                            bool transformZ = false ) = 0;
 
     /** Transforms the geometry using a QTransform object
      * @param t QTransform transformation

src/core/geometry/qgscircularstringv2.cpp

@@ -629,15 +629,16 @@ void QgsCircularStringV2::draw( QPainter& p ) const
   p.drawPath( path );
 }
 
-void QgsCircularStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsCircularStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   clearCache();
 
   double* zArray = mZ.data();
 
   bool hasZ = is3D();
   int nPoints = numPoints();
-  if ( !hasZ )
+  bool useDummyZ = !hasZ || !transformZ;
+  if ( useDummyZ )
   {
     zArray = new double[nPoints];
     for ( int i = 0; i < nPoints; ++i )
@@ -646,7 +647,7 @@ void QgsCircularStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordi
     }
   }
   ct.transformCoords( nPoints, mX.data(), mY.data(), zArray, d );
-  if ( !hasZ )
+  if ( useDummyZ )
   {
     delete[] zArray;
   }

src/core/geometry/qgscircularstringv2.h

@@ -86,12 +86,8 @@ class CORE_EXPORT QgsCircularStringV2: public QgsCurveV2
     virtual QgsLineStringV2* curveToLine( double tolerance = M_PI_2 / 90, SegmentationToleranceType toleranceType = MaximumAngle ) const override;
 
     void draw( QPainter& p ) const override;
-
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
     void addToPainterPath( QPainterPath& path ) const override;
 

src/core/geometry/qgscompoundcurvev2.cpp

@@ -458,11 +458,11 @@ void QgsCompoundCurveV2::draw( QPainter& p ) const
   }
 }
 
-void QgsCompoundCurveV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsCompoundCurveV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   Q_FOREACH ( QgsCurveV2* curve, mCurves )
   {
-    curve->transform( ct, d );
+    curve->transform( ct, d, transformZ );
   }
   clearCache();
 }

src/core/geometry/qgscompoundcurvev2.h

@@ -86,11 +86,8 @@ class CORE_EXPORT QgsCompoundCurveV2: public QgsCurveV2
     void addVertex( const QgsPointV2& pt );
 
     void draw( QPainter& p ) const override;
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-       @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
     void addToPainterPath( QPainterPath& path ) const override;
     void drawAsPolygon( QPainter& p ) const override;

src/core/geometry/qgscurvepolygonv2.cpp

@@ -561,16 +561,16 @@ void QgsCurvePolygonV2::draw( QPainter& p ) const
   }
 }
 
-void QgsCurvePolygonV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsCurvePolygonV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   if ( mExteriorRing )
   {
-    mExteriorRing->transform( ct, d );
+    mExteriorRing->transform( ct, d, transformZ );
   }
 
   Q_FOREACH ( QgsCurveV2* curve, mInteriorRings )
   {
-    curve->transform( ct, d );
+    curve->transform( ct, d, transformZ );
   }
   clearCache();
 }

src/core/geometry/qgscurvepolygonv2.h

@@ -83,11 +83,8 @@ class CORE_EXPORT QgsCurvePolygonV2: public QgsSurfaceV2
     bool removeInteriorRing( int nr );
 
     virtual void draw( QPainter& p ) const override;
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
 
     virtual bool insertVertex( QgsVertexId position, const QgsPointV2& vertex ) override;

src/core/geometry/qgsgeometrycollectionv2.cpp

@@ -142,11 +142,11 @@ int QgsGeometryCollectionV2::dimension() const
   return maxDim;
 }
 
-void QgsGeometryCollectionV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsGeometryCollectionV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   Q_FOREACH ( QgsAbstractGeometryV2* g, mGeometries )
   {
-    g->transform( ct, d );
+    g->transform( ct, d, transformZ );
   }
   clearCache(); //set bounding box invalid
 }

src/core/geometry/qgsgeometrycollectionv2.h

@@ -70,11 +70,8 @@ class CORE_EXPORT QgsGeometryCollectionV2: public QgsAbstractGeometryV2
      */
     virtual bool removeGeometry( int nr );
 
-    /** Transforms the geometry using a coordinate transform
-     * @param ct coordinate transform
-     * @param d transformation direction
-     */
-    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    virtual void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                            bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
 #if 0
     virtual void clip( const QgsRectangle& rect ) override;

src/core/geometry/qgslinestringv2.cpp

@@ -599,13 +599,14 @@ QgsAbstractGeometryV2* QgsLineStringV2::toCurveType() const
  * See details in QEP #17
  ****************************************************************************/
 
-void QgsLineStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsLineStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   double* zArray = mZ.data();
 
   bool hasZ = is3D();
   int nPoints = numPoints();
-  if ( !hasZ )
+  bool useDummyZ = !hasZ || !transformZ;
+  if ( useDummyZ )
   {
     zArray = new double[nPoints];
     for ( int i = 0; i < nPoints; ++i )
@@ -614,7 +615,7 @@ void QgsLineStringV2::transform( const QgsCoordinateTransform& ct, QgsCoordinate
     }
   }
   ct.transformCoords( nPoints, mX.data(), mY.data(), zArray, d );
-  if ( !hasZ )
+  if ( useDummyZ )
   {
     delete[] zArray;
   }

src/core/geometry/qgslinestringv2.h

@@ -168,7 +168,8 @@ class CORE_EXPORT QgsLineStringV2: public QgsCurveV2
 
     void draw( QPainter& p ) const override;
 
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
 
     void addToPainterPath( QPainterPath& path ) const override;

src/core/geometry/qgspointv2.cpp

@@ -257,10 +257,18 @@ void QgsPointV2::clear()
   clearCache();
 }
 
-void QgsPointV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d )
+void QgsPointV2::transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d, bool transformZ )
 {
   clearCache();
-  ct.transformInPlace( mX, mY, mZ, d );
+  if ( transformZ )
+  {
+    ct.transformInPlace( mX, mY, mZ, d );
+  }
+  else
+  {
+    double z = 0.0;
+    ct.transformInPlace( mX, mY, z, d );
+  }
 }
 
 QgsCoordinateSequenceV2 QgsPointV2::coordinateSequence() const

src/core/geometry/qgspointv2.h

@@ -165,7 +165,8 @@ class CORE_EXPORT QgsPointV2: public QgsAbstractGeometryV2
     QDomElement asGML3( QDomDocument& doc, int precision = 17, const QString& ns = "gml" ) const override;
     QString asJSON( int precision = 17 ) const override;
     void draw( QPainter& p ) const override;
-    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform ) override;
+    void transform( const QgsCoordinateTransform& ct, QgsCoordinateTransform::TransformDirection d = QgsCoordinateTransform::ForwardTransform,
+                    bool transformZ = false ) override;
     void transform( const QTransform& t ) override;
     virtual QgsCoordinateSequenceV2 coordinateSequence() const override;
 

src/core/qgscoordinatetransform.h

@@ -159,11 +159,11 @@ class CORE_EXPORT QgsCoordinateTransform : public QObject
     // C style arrays.
     void transformInPlace( double& x, double& y, double &z, TransformDirection direction = ForwardTransform ) const;
 
-    // @note not available in python bindings
+    //! @note not available in python bindings
     void transformInPlace( float& x, float& y, double &z, TransformDirection direction = ForwardTransform ) const;
-    // @note not available in python bindings
+    //! @note not available in python bindings
     void transformInPlace( float& x, float& y, float& z, TransformDirection direction = ForwardTransform ) const;
-    // @note not available in python bindings
+    //! @note not available in python bindings
     void transformInPlace( QVector<float>& x, QVector<float>& y, QVector<float>& z,
                            TransformDirection direction = ForwardTransform ) const;
 

src/core/symbology-ng/qgslinesymbollayerv2.cpp

@@ -1063,7 +1063,7 @@ void QgsMarkerLineSymbolLayerV2::renderPolylineVertex( const QPolygonF& points,
       {
         //transform
         x = vPoint.x(), y = vPoint.y();
-        z = vPoint.z();
+        z = 0.0;
         if ( ct )
         {
           ct->transformInPlace( x, y, z );

src/core/symbology-ng/qgssymbolv2.cpp

@@ -115,7 +115,7 @@ QgsConstWkbPtr QgsSymbolV2::_getPoint( QPointF& pt, QgsRenderContext& context, Q
 
   if ( context.coordinateTransform() )
   {
-    double z = 0; // dummy variable for coordiante transform
+    double z = 0; // dummy variable for coordinate transform
     context.coordinateTransform()->transformInPlace( pt.rx(), pt.ry(), z );
   }
 
@@ -993,7 +993,7 @@ void QgsSymbolV2::renderFeature( const QgsFeature& feature, QgsRenderContext& co
         //transform
         x = vertexPoint.x();
         y = vertexPoint.y();
-        z = vertexPoint.z();
+        z = 0.0;
         if ( ct )
         {
           ct->transformInPlace( x, y, z );