Building tiles server

Hi everyone,

currently i'm working on my own .net implementation of a tiles server. I've made some progress but currently im facing a problem with gaps in the rendered lines (example motorways) Look at the image, there are gaps in the blue motorway. I'm rendering data based on the nodes and ways relations imported to my custom database. Any ideas what am I missing? I've already tried to include all types of 'roads' to my query.

Thank you for any suggestions :)

Here is the db structure, and a query answering scai's question So yes, all nodes seems to be imported correctly. and yes i am debuging the problem already for 2 days :) :

How data is rendered on the tile: i'm using this http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#C.23 to get lat and lng for each tile number (left top corner). Getting the +1 tile geoposition gives me right bottom corner. Let's call those two beginingGeoPosition and endGeoPosition. that gives me a set of nodes and their lat and lng.

Knowing my tiles are 256x256 i can get a pixel possition for each node on the tile:

var x = 256 * (node.Longitude - beginingGeoPosition.Longitude ) / (endGeoPosition.Longitude - beginingGeoPosition.Longitude )
var y = 256 * (node.Latitude - beginingGeoPosition.Latitude )/(endGeoPosition.Latitude -beginingGeoPosition.Latitude );

(currently it will work only for lat and lng > 0, but thats not the point)

so that gives us groups of points (for each way) on image tile positioned by their x and y. connectiong those points gives us a part of a motorway. Precisly in .net

gfx.DrawLines(new Pen(Color.Blue, 3), linePoints); it creates line through all the points in the linePoints array - each point has its x and y

and the full query looks like this.

select n.nodeid, n.latitude, n.longitude, wn.wayid, wt.tagname, wt.tagvalue, wn.orderid
                        from nodes n
                        join waynodes wn on n.nodeid = wn.nodeid
                        join waytags wt on wn.wayid = wt.wayid
                        where wt.tagname IN ('route', 'area:highway', 'highway') and wt.tagvalue IN ('motorway','trunk','primary','secondary','tertiary','unclassified', 'road', 'motorway_link','trunk_link','primary_link','secondary_link','tertiary_link','unclassified_link','road_link')
                        and n.latitude BETWEEN 52.30848 and 52.32191
                        and n.longitude BETWEEN 15.49072 and 15.5127
                        order by wn.orderid asc