[FEATURE] Rendering of scalar data on mesh layers

Rudimentary support for rendering of scalar data (e.g. water depth)
on mesh map layers.

Author: wonder-sk

python/core/auto_generated/mesh/qgsmeshdataprovider.sip.in

@@ -23,6 +23,10 @@ class QgsMeshDatasetValue
 QgsMeshDatasetValue is a vector or a scalar value on vertex or face of the mesh with
 support of nodata values
 
+.. note::
+
+   The API is considered EXPERIMENTAL and can be changed without a notice
+
 .. versionadded:: 3.2
 %End
 
@@ -59,6 +63,10 @@ Mesh is a  collection of vertices and faces in 2D or 3D space
 Base on the underlying data provider/format, whole mesh is either stored in memory or
 read on demand
 
+.. note::
+
+   The API is considered EXPERIMENTAL and can be changed without a notice
+
 .. versionadded:: 3.2
 %End
 
@@ -105,6 +113,10 @@ Dataset is a  collection of vector or scalar values on vertices or faces of the
 Base on the underlying data provider/format, whole dataset is either stored in memory or
 read on demand
 
+.. note::
+
+   The API is considered EXPERIMENTAL and can be changed without a notice
+
 .. versionadded:: 3.2
 %End
 
@@ -158,6 +170,10 @@ Base class for providing data for :py:class:`QgsMeshLayer`
 
 Responsible for reading native mesh data
 
+.. note::
+
+   The API is considered EXPERIMENTAL and can be changed without a notice
+
 .. seealso:: :py:class:`QgsMeshSource`
 
 .. versionadded:: 3.2

python/core/auto_generated/mesh/qgsmeshlayer.sip.in

@@ -64,6 +64,11 @@ is the MDAL connection string. QGIS must be built with MDAL support to allow thi
          QString uri = "test/land.2dm";
          QgsMeshLayer *scratchLayer = new QgsMeshLayer(uri, "My Scratch Layer",  "mdal");
 
+.. note::
+
+   The API is considered EXPERIMENTAL and can be changed without a notice
+
+
 .. versionadded:: 3.2
 %End
 
@@ -138,6 +143,8 @@ Toggle rendering of triangular (derived) mesh. Off by default
     void setActiveScalarDataset( int index = -1 );
     void setActiveVectorDataset( int index = -1 );
 
+    int activeScalarDataset() const;
+
   private: // Private methods
     QgsMeshLayer( const QgsMeshLayer &rhs );
 };

src/core/CMakeLists.txt

@@ -453,6 +453,7 @@ SET(QGIS_CORE_SRCS
   mesh/qgsmeshlayerrenderer.cpp
   mesh/qgsmeshmemorydataprovider.cpp
   mesh/qgstriangularmesh.cpp
+  mesh/qgsmeshlayerinterpolator.cpp
 
   geometry/qgsabstractgeometry.cpp
   geometry/qgsbox3d.cpp
@@ -1075,6 +1076,7 @@ SET(QGIS_CORE_HDRS
 
   mesh/qgstriangularmesh.h
   mesh/qgsmeshlayerrenderer.h
+  mesh/qgsmeshlayerinterpolator.h
 
   scalebar/qgsdoubleboxscalebarrenderer.h
   scalebar/qgsnumericscalebarrenderer.h

src/core/mesh/qgsmeshdataprovider.cpp

@@ -94,6 +94,10 @@ void QgsMeshDatasetValue::setX( double x )
   {
     mIsNodata = true;
   }
+  else
+  {
+    mIsNodata = false;
+  }
 }
 
 void QgsMeshDatasetValue::setY( double y )

src/core/mesh/qgsmeshdataprovider.h

@@ -43,6 +43,8 @@ typedef QMap<QString, QString> QgsMeshDatasetMetadata;
  * QgsMeshDatasetValue is a vector or a scalar value on vertex or face of the mesh with
  * support of nodata values
  *
+ * \note The API is considered EXPERIMENTAL and can be changed without a notice
+ *
  * \since QGIS 3.2
  */
 class CORE_EXPORT QgsMeshDatasetValue
@@ -83,6 +85,8 @@ class CORE_EXPORT QgsMeshDatasetValue
  * Base on the underlying data provider/format, whole mesh is either stored in memory or
  * read on demand
  *
+ * \note The API is considered EXPERIMENTAL and can be changed without a notice
+ *
  * \since QGIS 3.2
  */
 class CORE_EXPORT QgsMeshSource SIP_ABSTRACT
@@ -123,6 +127,8 @@ class CORE_EXPORT QgsMeshSource SIP_ABSTRACT
  * Base on the underlying data provider/format, whole dataset is either stored in memory or
  * read on demand
  *
+ * \note The API is considered EXPERIMENTAL and can be changed without a notice
+ *
  * \since QGIS 3.2
  */
 class CORE_EXPORT QgsMeshDatasetSource SIP_ABSTRACT
@@ -174,6 +180,8 @@ class CORE_EXPORT QgsMeshDatasetSource SIP_ABSTRACT
  *
  * Responsible for reading native mesh data
  *
+ * \note The API is considered EXPERIMENTAL and can be changed without a notice
+ *
  * \see QgsMeshSource
  * \since QGIS 3.2
  */

src/core/mesh/qgsmeshlayer.cpp

@@ -129,13 +129,25 @@ void QgsMeshLayer::toggleTriangularMeshRendering( bool toggle )
 
 void QgsMeshLayer::setActiveScalarDataset( int index )
 {
+  if ( index < 0 )
+  {
+    mActiveScalarDataset = -1;
+    return;
+  }
+
   Q_ASSERT( dataProvider()->datasetCount() > index );
   if ( dataProvider()->datasetHasScalarData( index ) )
     mActiveScalarDataset = index;
 }
 
 void QgsMeshLayer::setActiveVectorDataset( int index )
 {
+  if ( index < 0 )
+  {
+    mActiveVectorDataset = -1;
+    return;
+  }
+
   Q_ASSERT( dataProvider()->datasetCount() > index );
   if ( !dataProvider()->datasetHasScalarData( index ) )
     mActiveVectorDataset = index;

src/core/mesh/qgsmeshlayer.h

@@ -82,6 +82,8 @@ struct QgsMesh;
  *     QgsMeshLayer *scratchLayer = new QgsMeshLayer(uri, "My Scratch Layer",  "mdal");
  * \endcode
  *
+ * \note The API is considered EXPERIMENTAL and can be changed without a notice
+ *
  * \since QGIS 3.2
  */
 class CORE_EXPORT QgsMeshLayer : public QgsMapLayer
@@ -145,6 +147,8 @@ class CORE_EXPORT QgsMeshLayer : public QgsMapLayer
     void setActiveScalarDataset( int index = -1 );
     void setActiveVectorDataset( int index = -1 );
 
+    int activeScalarDataset() const { return mActiveScalarDataset; }
+
   private: // Private methods
 
     /**