[Feature][Mesh][3D] new 3D mesh layer renderer

[vcloarec]

This PR change the 3D mesh renderer approach
The new approach is based on OpenGL shader. By this way, the GPU handles rendering wireframe and color ramp shading.

There are two entries to render the mesh layer in the 3D view :

• choose the mesh as terrain in the config widget
• activate the 3D view in the layer properties.

The user can choose those settings

• enable/disable smooth triangles
• enable/disable wireframe
• choose the line width and the line color of the wireframe
• change the verticale scale
• choose the style of the rendering : unique color or color ramp shading
• settings the color ramp shading as for raster layer

For now, the mesh can be rendered as a TIN but rendering dataset is not supported. However the infrastructure is adapted for a future PR.

• Commit messages are descriptive and explain the rationale for changes
• Commits which fix bugs include Fixes #11111 at the bottom of the commit message
• I have read the QGIS Coding Standards and this PR complies with them
• New unit tests have been added for core changes
• I have run the scripts/prepare-commit.sh script before each commit
• I have evaluated whether it is appropriate for this PR to be backported, backport requests are left as label or comment

[NathanW2]

Holy heck! Win!

…

[nyalldawson]

Looks awesome!

[wonder-sk]

Looking great!

(Note: I have done a couple of review iterations with Vincent earlier this week and in the current state it is good to get merged for 3.12 in my opinion.)

[nyalldawson]

I looked over the code and couldn't see any issues, but I'm familiar neither with the 3d code nor the mesh provider, so it was only a very general review. If @wonder-sk is happy, then merge away!

[Saijin-Naib]

Incredible!

[DelazJ]

If there's anything new in the GUI or worth documenting, can someone label this PR appropriately so that we get the PR description in docs repo? The current issue report description is rather... Thanks

[qgis-bot]

@vcloarec
This pull request has been tagged as requiring documentation.

A documentation ticket will be opened at https://github.com/qgis/QGIS-Documentation when this PR is merged.

Please update the description (not the comments) with helpful description and screenshot to help the work from documentors.
Also, any commit having [needs-doc] or [Needs Documentation] in will see its message pushed to the issue, so please be as verbose as you can.

Thank you!

[qgis-bot]

@vcloarec
A documentation ticket has been opened at qgis/QGIS-Documentation#4806
It is your responsibility to visit this ticket and add as much detail as possible for the documentation team to correctly document this change.
Thank you!

[qgis-bot]

@vcloarec
This pull request has been tagged as requiring documentation.

A documentation ticket will be opened at https://github.com/qgis/QGIS-Documentation when this PR is merged.

Please update the description (not the comments) with helpful description and screenshot to help the work from documentors.
Also, any commit having [needs-doc] or [Needs Documentation] in will see its message pushed to the issue, so please be as verbose as you can.

Thank you!

[qgis-bot]

@vcloarec
A documentation ticket has been opened at qgis/QGIS-Documentation#4909
It is your responsibility to visit this ticket and add as much detail as possible for the documentation team to correctly document this change.
Thank you!