label underscaling

[ansis]

We need to place labels at least a couple zoom levels lower than the tile zoom to prevent labels from flashing when zooming out.

[kkaefer]

yeah, noticed that too. Problem is that if we do this, we get a massive amount of collisions in the rtree.

[ansis]

Adding a second rtree should solve this reasonably well.

[kkaefer]

7c1fb59 adds back stencil clipping for labels because the pan tile often has the same labels in slightly different spots, which looks weird. However, this also makes this bug more visible.

[ansis]

same labels in slightly different spots

Do you remember if these were point or line labels?

[kkaefer]

point labels. I'm talking about city labels being duplicated, one from the pan tile and once from the actual tile.

[ansis]

#194 has two ideas about fixing that. Thinking about that now, I think B is the only one that would really work

[ansis]

Done in eb0bfc8 - performance made acceptable by ea6a4b3