As for intersections: whenever a line segment crosses another line segment at the same zorder. Right now we take the first polygon, then clip the second so they don't z-fight - it ends up looking that the first line is on top of the second. The new intersection code generates new polygons at the intersection that meet at a point, as such the texture coordinates 'line up' in v to form an intersection. Right now - I'm doing it so the yellow taxiway lines with a black border always have yellow in the middle, and black borders on the sides, and looks correct. Highway intersections would be similar, but the intersection point would need to vary with the intersection type - so for instance, highway on ramps don't intersect the highway in the middle lane - they need to intersect at the outermost lane, etc.

In the future, yes - I plan to have just landclass scenery as the terrain base, and the roads, streams, and rail draped on top. This will be part of the LOD scheme - only a few tiles will load the roads. I haven't decided how many .BTGs - perhaps keep motoryways seperate - as you can see motorways quite a ways into the distance... It will slightly decrease the landclass triangle count, but I still plan on flattening the terrain where roads go. These 'flattening' polygons will be wider and longer than the OSM feature data, so it will probably reduce the terrain complexity a bit. These polys will also contain a flag so that the autogen handler would not place trees / building on these triangles. An autogen exclusion mask, so to speak.