Update: Dynamic loading

In the previous system, one roadlink may be referenced in several nodes of the quadtree. This is to make sure that the road is loaded, whatever angle you come at it from. However, this means that if a roadlink is referenced in fifteen nodes it could get loaded fifteen times. Not only does this slow down loading, but it slows down rendering (even with the appropriate culling, it still draws the same object several times)

I updated this process so that the loading thread calls a function isTALoaded on the graphics object, which returns true if the topographic data for a roadlink or roadnode has already been loaded. This has decreased both loading and rendering times significantly.