[mesh] [feature] App widgets for styling mesh layers

[QGIS-feature-tracker]

Original commit: qgis/QGIS@aeea184 by PeterPetrik

• Adding datasets to mesh layer from properties panel
• Information and source panel in properties panel
• Selection of active dataset (properties or styling panel)
• Styling of contours/scalars (properties or styling panel)
• Styling of mesh frame (properties or styling panel)
• Styling of vector arrows (properties or styling panel)

[havatv]

This will probably have effects on illustrations in (a new mesh layer section of?) the user manual.

[saberraz]

As @DelazJ suggested in https://issues.qgis.org/issues/21065, I am moving the discussion here:

It will be good to group all mesh related issues and have a chapter. Here is my proposed outline which makes it future proof (with the additional features in pipeline):

Working with Mesh Data:

• Mesh Properties
  • Supported formats: to cover various formats: netcdf, grib, hdf5, etc
  • Information Properties
  • Source Properties: how to assign dataset to mesh
  • Symbology: covering vector and contour styles, time slider and various blending mode
• Mesh Analysis
  • Mesh Calculator (for 3.6)
  • Various mesh to vector/raster algs (3.8)

[DelazJ]

As @DelazJ suggested in https://issues.qgis.org/issues/21065, I am moving the discussion here:

👍 @saberraz

It will be good to group all mesh related issues and have a chapter. Here is my proposed outline which makes it future proof (with the additional features in pipeline):

I don't know if all the mesh related issues should be at a single place but I think the format deserves its chapter.

Working with Mesh Data:

* Mesh Properties
  
  * Supported formats: to cover various formats: netcdf, grib, hdf5, etc

I don't know what is planned as content here but we also have a dedicated "supported data chapter" that aims to explain and collect particular details regarding formats (vector and raster for the moment -needs more love- but mesh could be welcome). That said, I'm not familiar at all with this format...

  * Information Properties
  * Source Properties: how to assign dataset to mesh
  * Symbology: covering vector and contour styles, time slider and various blending mode

👍

* Mesh Analysis

If these are served as algs (presumably in >3.6), maybe should they go to the Processing chapter?

[havatv]

@DelazJ, could we close this one (the chapter is in place, and much is already included there)? In my opinion, it would be better to close and encourage more specific issues for the missing parts.