This is a fast approach on how to add more nodes to the edges of the tiles. This is required for a nice rendering on non-Mercator projections. The results are pretty good, as seen on the second screenshot(first screenshot is without the added nodes).
Using GeoDataCoordinates::interpolate() would be better(?) approach to generate the added nodes, but that would require to translate from QPolygonF back to GeoDataLineString in the cutting algorithm, and then convert it to a QList<QSharedPointer<LinkedPoint>>. If there is no visible benefit from using that approach, I would stick with this.
The formula to calculate the number of nodes to add can be changed,
MAXIMUM_POINTS_TO_ADD - zoomLevel
is only for demonstration. Suggestions are welcome.
Before (problematic spots marked):