[OSM-dev] Map rendering code... API or database direct?

[Raphaël Jacquot]

[gah, stupid reply-to headers]

immanuel.scholz at gmx.de wrote:
> There are two solutions to this: Either search through ALL line segments in 
> the data base and look whether they cross any of your 4 borders of the tile 
> to be rendered. This is slow but works everytime.
> 
> The other is to restrict the maximum length one line segment can have (or just 
> assume and hope they are restricted) and grab all data from your tile plus 
> the line segment offset widened. Then draw just all line segments and clip 
> your tile accordingly out of the bigger picture.
> 
> Of course, you can combine both methods ;-)

there is another better way yet, available at the sql level...
select all line segments that have a "foot" in the tile you're
interested in.
something like

if (node_a in [tile]) or (node_b in [tile]) then
	draw_segment
end