QgsTerrainEntity: remove whole terrain reload when 3D symbols are updated

[benoitdm-oslandia]

Currently, whenever a user opens the 3D style panel, enables the automatic update checkbox, and modifies settings unrelated to terrain, QGIS deletes and redraws all terrain entities. This PR removes the link between layer changes and terrain reloading.

[github-actions]

🪟 Windows Qt6 builds

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(Built from commit bc44276)

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This app is not notarized, run sudo xattr -d com.apple.quarantine /Applications/QGIS*.app to avoid the warning
(Built from commit bc44276)

[uclaros]

Why are both repaintRequested and styleChanged needed?

[benoitdm-oslandia]

This seems right to me as styleChanged and repaintRequested look like they are not part of the same workflow. The slot/signal workflow looks a bit messy to me, I may be wrong!

[uclaros]

Can you explain the case where styleChanged is emitted but repaintRequested is not?

[benoitdm-oslandia]

@nyalldawson @uclaros I keep only repaintRequested?

[uclaros]

The same logic is used for globe chunked entity and map overlay entity. Should these not be updated to have matching logic?

[benoitdm-oslandia]

The same logic is used for globe chunked entity and map overlay entity. Should these not be updated to have matching logic?

Can you point out the code please?

[uclaros]

QGIS/src/3d/qgsglobechunkedentity.cpp

Lines 545 to 549 in 0cd2815

	void QgsGlobeEntity::onLayersChanged()
	{
	connectToLayersRepaintRequest();
	invalidateMapImages();
	}

and

QGIS/src/3d/qgsmapoverlayentity.cpp

Lines 96 to 100 in 0cd2815

	void QgsMapOverlayEntity::onLayersChanged()
	{
	connectToLayersRepaintRequest();
	invalidateMapImage();
	}