Add 3D extent to providers (1st stage)

[benoitdm-oslandia]

This PR brings core modifications to allow providers to handle 3D extent. This is the first stage to prepare next PRs with dedicated modifications per provider.

• we add basic member functions to QgsDataProvider to handle 3D extent
• homogenize elevationdataproperties usage
• update QgsMapLayer to support 3D extent

Funded by CEA/DAM @renardf

cc @ptitjano

[nyalldawson]

This is great! Can you add the missing doxygen since notations too? (I assume this is targeting 3.36?)

[nirvn]

@benoitdm-oslandia , exciting stuff! What immediately comes to mind here is the possibility to do elevation filtering for the map canvas (the same way we do temporal filtering) with provider-side filtering capability. Lovely.

Out of curiosity, what are you guys planning to do with this?

[benoitdm-oslandia]

@benoitdm-oslandia , exciting stuff! What immediately comes to mind here is the possibility to do elevation filtering for the map canvas (the same way we do temporal filtering) with provider-side filtering capability. Lovely.

Out of curiosity, what are you guys planning to do with this?

@nirvn we are looking to push an improved extent filtering in the 3D view like this preview:

[benoitdm-oslandia]

@rouault @nyalldawson can you review this PR please?

[lbartoletti]

LGTM, except for a minor nitpick

[rouault]

As I mentionned I'm a bit nervous for performance reasons seing QgsVectorLayer::extent() to be redirected to QgsVectorLayer::extent3D().toRectangle().
At least, perhaps just as a temporary measure, it would probably be best if QgsVectorLayer::extent() implementation was left unmodified (as well as QgsVectorLayer::sourceExtent(). If after all the dust has settled there's a way of unifying QgsVectorLayer::extent() and extent3D(), that's be good of course

[benoitdm-oslandia]

As I mentionned I'm a bit nervous for performance reasons seing QgsVectorLayer::extent() to be redirected to QgsVectorLayer::extent3D().toRectangle().
At least, perhaps just as a temporary measure, it would probably be best if QgsVectorLayer::extent() implementation was left unmodified (as well as QgsVectorLayer::sourceExtent(). If after all the dust has settled there's a way of unifying QgsVectorLayer::extent() and extent3D(), that's be good of course

I can re-add the previous code for the QgsVectorLayer::extent().

[benoitdm-oslandia]

@rouault @lbartoletti @nyalldawson all requests are fulfilled. Is it OK for you?

[benoitdm-oslandia]

🍾