[OSM-dev] mod_tile meta-tiling looses png transparency

[mandrake at linux.fjfi.cvut.cz]

Hi all,

I'm having a problem with mod_tile. I'm using it together with Mapnik  
to render an overlay map, so I need a transparent background in tiles.  
Mapnik does this just fine by setting attribute bgcolor="transparent"  
in osm.xml file. However, mod_tile groups the mapnik tiles into a  
.meta file and the transparency gets lost there. When I use  
convert_meta to unpack the meta file, the background is black.
Somebody had the same problem here either,
http://www.nabble.com/layer-transperancy-td16639745.html
but the thread seems to be dead already with no solution.
Could somebody please look at it? Hope it is not too complicated to fix.

I tried to override the problem by swithing the meta-tiling off by  
commenting out the
#define METATILE (8)
line in render_config.h. Separate png files are actually good enough  
to me since my overlay is quite simple. But I run into few compiling  
problems, which I was unable to fix.
Thanks for any advice or fix!

mendrejk

BTW: I compiled mod_tile from SVN approx. two weeks ago.