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

immanuel.scholz at gmx.de immanuel.scholz at gmx.de
Thu Mar 30 13:10:02 BST 2006


On Thursday 30 March 2006 14:02, Richard Fairhurst wrote:
> Imi wrote:
> > Hi,
> >
> >> SELECT id,path FROM segments WHERE
> >>     ((xmin BETWEEN $bbox_xmin AND $bbox_xmax) OR
> >>      (xmax BETWEEN $bbox_xmin AND $bbox_xmax) OR
> >>      (xmin<$bbox_xmin AND xmax>$bbox_xmax)) AND
> >>     ((ymin BETWEEN $bbox_ymin AND $bbox_ymax) OR
> >>      (ymax BETWEEN $bbox_ymin AND $bbox_ymax) OR
> >>      (ymin<$bbox_ymin AND ymax>$bbox_ymax))
> >> [SQL snipped]
> >> where xmin, xmax, ymin and ymax are the bounding box of each segment,
> >> and $bbox_xmin, $bbox_xmax etc. are the bounding box of the current
> >> map
> >> view (tile).
> >
> > See my other posting why this is still flawed.
>
> It works for your ASCII art suggestion, doesn't it?

Yes, you are right, I am sorry. This is indeed the algorithm represented in 
SQL to choose very quickly all segments that could cross the actual bounding 
box.


Ciao, Imi.




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