[MESH] scalar color settings depending on classification (#36313)

* [MESH] [FEATURE] Sets meh color ramp classification from metadata read by MDAL driver.
Some mesh layer formats can provide values that can be compressed by categorizing values in consecutive intervals, each represent by an integer or byte. MDAL has the capabilities to recognize this dataset type and store the bounds of each class an the units in the metadata.
QGIS uses this metadata to setup adapted color ramp shader.

* [MDAL] update to pre-release 0.5.92

external/mdal/frmts/mdal_3di.cpp

@@ -194,10 +194,16 @@ std::set<std::string> MDAL::Driver3Di::ignoreNetCDFVariables()
   return ignore_variables;
 }
 
-void MDAL::Driver3Di::parseNetCDFVariableMetadata( int varid, const std::string &variableName, std::string &name, bool *is_vector, bool *is_x )
+void MDAL::Driver3Di::parseNetCDFVariableMetadata( int varid,
+    std::string &variableName,
+    std::string &name,
+    bool *is_vector,
+    bool *isPolar,
+    bool *is_x )
 {
   *is_vector = false;
   *is_x = true;
+  *isPolar = false;
 
   std::string long_name = mNcFile->getAttrStr( "long_name", varid );
   if ( long_name.empty() )
@@ -209,6 +215,7 @@ void MDAL::Driver3Di::parseNetCDFVariableMetadata( int varid, const std::string
     }
     else
     {
+      variableName = standard_name;
       if ( MDAL::contains( standard_name, "_x_" ) )
       {
         *is_vector = true;
@@ -228,6 +235,7 @@ void MDAL::Driver3Di::parseNetCDFVariableMetadata( int varid, const std::string
   }
   else
   {
+    variableName = long_name;
     if ( MDAL::contains( long_name, " in x direction" ) )
     {
       *is_vector = true;
@@ -245,3 +253,9 @@ void MDAL::Driver3Di::parseNetCDFVariableMetadata( int varid, const std::string
     }
   }
 }
+
+std::vector<std::pair<double, double>> MDAL::Driver3Di::parseClassification( int varid ) const
+{
+  MDAL_UNUSED( varid );
+  return std::vector<std::pair<double, double>>();
+}

external/mdal/frmts/mdal_3di.hpp

@@ -50,8 +50,13 @@ namespace MDAL
       std::string getCoordinateSystemVariableName() override;
       std::string getTimeVariableName() const override;
       std::set<std::string> ignoreNetCDFVariables() override;
-      void parseNetCDFVariableMetadata( int varid, const std::string &variableName,
-                                        std::string &name, bool *is_vector, bool *is_x ) override;
+      void parseNetCDFVariableMetadata( int varid,
+                                        std::string &variableName,
+                                        std::string &name,
+                                        bool *is_vector,
+                                        bool *isPolar,
+                                        bool *is_x ) override;
+      std::vector<std::pair<double, double>> parseClassification( int varid ) const override;
 
       //! Returns number of vertices
       size_t parse2DMesh();