[FEATURE] Scalar/vector data in mesh data providers

Reading and processing scalar (e.g. water depth) and vector (e.g. velocity) data from mesh data providers (e.g. MDAL)
qgis · May 16, 2018 · 3154102 · 3154102
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commit 3154102
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diff --git a/python/core/auto_generated/mesh/qgsmeshdataprovider.sip.in b/python/core/auto_generated/mesh/qgsmeshdataprovider.sip.in
@@ -10,8 +10,44 @@
 
 
 
-typedef QgsPoint QgsMeshVertex; //xyz coords of vertex
-typedef QVector<int> QgsMeshFace; //list of vertex indexes
+typedef QgsPoint QgsMeshVertex;
+
+typedef QVector<int> QgsMeshFace;
+
+typedef QMap<QString, QString> QgsMeshDatasetMetadata;
+
+class QgsMeshDatasetValue
+{
+%Docstring
+
+QgsMeshDatasetValue is a vector or a scalar value on vertex or face of the mesh with
+support of nodata values
+
+.. versionadded:: 3.2
+%End
+
+%TypeHeaderCode
+#include "qgsmeshdataprovider.h"
+%End
+  public:
+    QgsMeshDatasetValue( double x,
+                         double y );
+    QgsMeshDatasetValue( double scalar );
+    QgsMeshDatasetValue( );
+
+    ~QgsMeshDatasetValue();
+    void setNodata( bool nodata = true );
+    bool isNodata() const;
+    bool isScalar() const;
+    double scalar() const; //length for vectors, value for scalars
+    void set( double scalar );
+    void setX( double x );
+    void setY( double y );
+    double x() const;
+    double y() const;
+    bool operator==( const QgsMeshDatasetValue &other ) const;
+
+};
 
 class QgsMeshSource /Abstract/
 {
@@ -61,7 +97,61 @@ read on demand
 %End
 };
 
-class QgsMeshDataProvider: QgsDataProvider, QgsMeshSource
+class QgsMeshDatasetSource /Abstract/
+{
+%Docstring
+Dataset is a  collection of vector or scalar values on vertices or faces of the mesh
+
+Base on the underlying data provider/format, whole dataset is either stored in memory or
+read on demand
+
+.. versionadded:: 3.2
+%End
+
+%TypeHeaderCode
+#include "qgsmeshdataprovider.h"
+%End
+  public:
+    virtual ~QgsMeshDatasetSource();
+
+    virtual bool addDataset( const QString &uri ) = 0;
+%Docstring
+ Associate dataset with the mesh
+%End
+
+    virtual int datasetCount() const = 0;
+%Docstring
+ Return number of datasets loaded
+%End
+
+    virtual bool datasetHasScalarData( int index ) const = 0;
+%Docstring
+ Whether dataset has scalar data associated
+%End
+
+    virtual bool datasetIsOnVertices( int index ) const = 0;
+%Docstring
+ Whether dataset is on vertices
+%End
+
+    virtual QgsMeshDatasetMetadata datasetMetadata( int index ) const = 0;
+%Docstring
+ Return dataset metadata
+%End
+
+    virtual QgsMeshDatasetValue datasetValue( int datasetIndex, int valueIndex ) const = 0;
+%Docstring
+ Return value associated with the index from the dataset
+%End
+
+    virtual bool datasetIsValid( int index ) const = 0;
+%Docstring
+ Return whether dataset is valid
+%End
+};
+
+
+class QgsMeshDataProvider: QgsDataProvider, QgsMeshSource, QgsMeshDatasetSource
 {
 %Docstring
 Base class for providing data for :py:class:`QgsMeshLayer`

diff --git a/python/core/auto_generated/mesh/qgsmeshlayer.sip.in b/python/core/auto_generated/mesh/qgsmeshlayer.sip.in
@@ -52,6 +52,8 @@ E.g. to create mesh with one quad and one triangle
         );
         QgsMeshLayer *scratchLayer = new QgsMeshLayer(uri, "My Scratch layer", "memory_mesh");
 
+Add datasets by adding them through data provider, :py:func:`QgsMeshDatasetSource.addDataset`
+
 \subsection mdal MDAL data provider (mdal)
 
 Accesses data using the MDAL drivers (https://github.com/lutraconsulting/MDAL). The url
@@ -133,6 +135,9 @@ Returns a line symbol used for rendering of triangular (derived) mesh.
 Toggle rendering of triangular (derived) mesh. Off by default
 %End
 
+    void setActiveScalarDataset( int index = -1 );
+    void setActiveVectorDataset( int index = -1 );
+
   private: // Private methods
     QgsMeshLayer( const QgsMeshLayer &rhs );
 };

diff --git a/src/core/mesh/qgsmeshdataprovider.cpp b/src/core/mesh/qgsmeshdataprovider.cpp
@@ -16,6 +16,7 @@
  ***************************************************************************/
 
 #include "qgsmeshdataprovider.h"
+#include "qgis.h"
 
 QgsMeshDataProvider::QgsMeshDataProvider( const QString &uri )
   : QgsDataProvider( uri )
@@ -38,3 +39,100 @@ QgsRectangle QgsMeshDataProvider::extent() const
   return rec;
 
 }
+
+QgsMeshDatasetValue::QgsMeshDatasetValue( double x, double y )
+{
+  setX( x );
+  setY( y );
+}
+
+QgsMeshDatasetValue::QgsMeshDatasetValue( double scalar )
+{
+  set( scalar );
+}
+
+void QgsMeshDatasetValue::setNodata( bool nodata )
+{
+  mIsNodata = nodata;
+}
+
+bool QgsMeshDatasetValue::isNodata() const
+{return mIsNodata;}
+
+bool QgsMeshDatasetValue::isScalar() const
+{
+  return mIsScalar;
+}
+
+double QgsMeshDatasetValue::scalar() const
+{
+  if ( isNodata() )
+  {
+    return std::numeric_limits<double>::quiet_NaN();
+  }
+
+  if ( isScalar() )
+  {
+    return mX;
+  }
+  else
+  {
+    return std::sqrt( ( mX ) * ( mX ) + ( mY ) * ( mY ) );
+  }
+}
+
+void QgsMeshDatasetValue::set( double scalar )
+{
+  setX( scalar );
+  mIsScalar = true;
+}
+
+void QgsMeshDatasetValue::setX( double x )
+{
+  mX = x;
+  if ( std::isnan( x ) )
+  {
+    mIsNodata = true;
+  }
+}
+
+void QgsMeshDatasetValue::setY( double y )
+{
+  mY = y;
+  if ( std::isnan( y ) )
+  {
+    mIsScalar = true;
+  }
+}
+
+double QgsMeshDatasetValue::x() const
+{
+  return mX;
+}
+
+double QgsMeshDatasetValue::y() const
+{
+  return mY;
+}
+
+bool QgsMeshDatasetValue::operator==( const QgsMeshDatasetValue &other ) const
+{
+  bool equal = true;
+  if ( isNodata() )
+    equal = other.isNodata();
+  else
+  {
+    if ( isScalar() )
+    {
+      equal &= other.isScalar();
+      equal &= qgsDoubleNear( other.x(), mX, 1E-8 );
+    }
+    else
+    {
+      equal &= !other.isScalar();
+      equal &= qgsDoubleNear( other.x(), mX, 1E-8 );
+      equal &= qgsDoubleNear( other.y(), mY, 1E-8 );
+    }
+  }
+  return equal;
+}
diff --git a/src/core/mesh/qgsmeshdataprovider.h b/src/core/mesh/qgsmeshdataprovider.h
@@ -25,9 +25,54 @@
 
 #include <QVector>
 #include <QString>
+#include <QMap>
+#include <limits>
 
-typedef QgsPoint QgsMeshVertex; //xyz coords of vertex
-typedef QVector<int> QgsMeshFace; //list of vertex indexes
+//! xyz coords of vertex
+typedef QgsPoint QgsMeshVertex;
+
+//! List of vertex indexes
+typedef QVector<int> QgsMeshFace;
+
+//! Dataset's metadata key:value map
+typedef QMap<QString, QString> QgsMeshDatasetMetadata;
+
+/**
+ * \ingroup core
+ *
+ * QgsMeshDatasetValue is a vector or a scalar value on vertex or face of the mesh with
+ * support of nodata values
+ *
+ * \since QGIS 3.2
+ */
+class CORE_EXPORT QgsMeshDatasetValue
+{
+    Q_GADGET
+
+  public:
+    QgsMeshDatasetValue( double x,
+                         double y );
+    QgsMeshDatasetValue( double scalar );
+    QgsMeshDatasetValue( ) = default;
+
+    ~QgsMeshDatasetValue() = default;
+    void setNodata( bool nodata = true );
+    bool isNodata() const;
+    bool isScalar() const;
+    double scalar() const; //length for vectors, value for scalars
+    void set( double scalar );
+    void setX( double x );
+    void setY( double y ) ;
+    double x() const;
+    double y() const;
+    bool operator==( const QgsMeshDatasetValue &other ) const;
+
+  private:
+    double mX  = std::numeric_limits<double>::quiet_NaN();
+    double mY  = std::numeric_limits<double>::quiet_NaN();
+    bool mIsNodata = true;
+    bool mIsScalar = true;
+};
 
 /**
  * \ingroup core
@@ -73,14 +118,66 @@ class CORE_EXPORT QgsMeshSource SIP_ABSTRACT
 
 /**
  * \ingroup core
-  * Base class for providing data for QgsMeshLayer
-  *
-  * Responsible for reading native mesh data
-  *
-  * \see QgsMeshSource
-  * \since QGIS 3.2
-  */
-class CORE_EXPORT QgsMeshDataProvider: public QgsDataProvider, public QgsMeshSource
+ * Dataset is a  collection of vector or scalar values on vertices or faces of the mesh
+ *
+ * Base on the underlying data provider/format, whole dataset is either stored in memory or
+ * read on demand
+ *
+ * \since QGIS 3.2
+ */
+class CORE_EXPORT QgsMeshDatasetSource SIP_ABSTRACT
+{
+  public:
+    //! Dtor
+    virtual ~QgsMeshDatasetSource() = default;
+
+    /**
+     * \brief Associate dataset with the mesh
+     */
+    virtual bool addDataset( const QString &uri ) = 0;
+
+    /**
+     * \brief Return number of datasets loaded
+     */
+    virtual int datasetCount() const = 0;
+
+    /**
+     * \brief Whether dataset has scalar data associated
+     */
+    virtual bool datasetHasScalarData( int index ) const = 0;
+
+    /**
+     * \brief Whether dataset is on vertices
+     */
+    virtual bool datasetIsOnVertices( int index ) const = 0;
+
+    /**
+     * \brief Return dataset metadata
+     */
+    virtual QgsMeshDatasetMetadata datasetMetadata( int index ) const = 0;
+
+    /**
+     * \brief Return value associated with the index from the dataset
+     */
+    virtual QgsMeshDatasetValue datasetValue( int datasetIndex, int valueIndex ) const = 0;
+
+    /**
+     * \brief Return whether dataset is valid
+     */
+    virtual bool datasetIsValid( int index ) const = 0;
+};
+
+
+/**
+ * \ingroup core
+ * Base class for providing data for QgsMeshLayer
+ *
+ * Responsible for reading native mesh data
+ *
+ * \see QgsMeshSource
+ * \since QGIS 3.2
+ */
+class CORE_EXPORT QgsMeshDataProvider: public QgsDataProvider, public QgsMeshSource, public QgsMeshDatasetSource
 {
     Q_OBJECT
 

diff --git a/src/core/mesh/qgsmeshlayer.cpp b/src/core/mesh/qgsmeshlayer.cpp
@@ -127,6 +127,20 @@ void QgsMeshLayer::toggleTriangularMeshRendering( bool toggle )
   triggerRepaint();
 }
 
+void QgsMeshLayer::setActiveScalarDataset( int index )
+{
+  Q_ASSERT( dataProvider()->datasetCount() > index );
+  if ( dataProvider()->datasetHasScalarData( index ) )
+    mActiveScalarDataset = index;
+}
+
+void QgsMeshLayer::setActiveVectorDataset( int index )
+{
+  Q_ASSERT( dataProvider()->datasetCount() > index );
+  if ( !dataProvider()->datasetHasScalarData( index ) )
+    mActiveVectorDataset = index;
+}
+
 void QgsMeshLayer::fillNativeMesh()
 {
   Q_ASSERT( !mNativeMesh );