[postgis-users] Offset

Bob Pawley rjpawley at shaw.ca
Thu Aug 14 11:02:35 PDT 2008

I am using the following function that works quite well.

However, the center of the geometry (arrowhead) is moved to the center of 
the geometry.

Is there someway of applying an offset so that the point of the arrow can be 
moved so it is touching the boundary of the geometry??


Insert into temparrow (the_geom, process_id, orient)
 Select st_translate (graphics.utilities_dgm.the_geom,
 st_x (st_centroid (p_id.p_id.ithe_geom)) -
 st_x (st_centroid (graphics.utilities_dgm.the_geom)),
 st_y (st_centroid (p_id.p_id.ithe_geom))-
 st_y (st_centroid (graphics.utilities_dgm.the_geom))), 
(p_id.processes.process_id), (p_id.processes.ip_orient)
 From graphics.utilities_dgm, p_id.p_id, p_id.processes, processes_count
 where graphics.utilities_dgm.utilities_description = 'Arrow_Flow_Direction'
 and graphics.utilities_dgm.orientation = p_id.processes.ip_orient
 and p_id.processes.process_id = processes_count.process_id ; 

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