[FEATURE] Introduces mesh virtual datasets
With the mesh calculator the user can choose to create those "virtual" dataset groups that will be added to the layer. Then, for these dataset groups, values are not stored in memory but each dataset is calculated when needed whit the formula entered in the mesh calculator.
Those virtual dataset groups are saved with the project.
If needed, the user can remove them or can persist them on files to make them persistent.
Co-authored-by: Étienne Trimaille <gustrimaille@yahoo.fr>
[FEATURE] Introduces memory dataset groups for mesh layer. These dataset groups are temporary and are not kept when the project is closed.
Memory dataset groups can be created from the mesh calculator with a new option.
Allows the possibility to remove or save these memory dataset groups to a file with specified driver.
[FEATURE] Implements resampling from values on vertices to values on faces with the neighbor average method. (note that resampling method for datasets defined on faces, e.g., the value on vertices is calculated from value on faces was added in the previous QGIS release)
The default method is set to "none" for resampling from vertices to faces and to "neighbor average" for resampling from faces to vertices. Then the default rendering is now always smooth.
* [feature] support datasets with data defined on faces in mesh calculator, fix#30219, fix#30170
added "driver" and "group name" to the calculator interface.
MDAL now supports 3 drivers for storing results, so user must be able to choose appropriate driver and dataset group name (some drivers store multiple groups to 1 file)
The mesh styling dialog now has new combo box for selection of resampling method for datesets defined on faces.
Also the analysis library has new class QgsMeshContours with export function for contour lines and contour polygons.
Similarly to raster calculator, mesh calculator can take dataset groups from current mesh layer and
combine them with various aritmentic/logical operators to new dataset group.
