[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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