[mkgmap-dev] Preservation of order not working

Fri Feb 27 18:03:34 GMT 2009

Hello!

My application makes heavy use of a layering concept that puts items in 
a particular order so they are drawn on top of each other on the garmin. 
This is used to draw bridges/tunnels in the proper order and to 
construct composite elements by overlaying multiple lines or icons in a 
particular order.

Versions of mkgamp up to 590 did maintain the order of elements, in 
later versions the order was random due to use of a hash map, then 
maintaining the order was restored - theoretically.

I now tried to migrate my application to work with current versions of 
mkgmap, but the drawing order still does not correspond to the order in 
the input osm file.

In the particular use case I attempt to create markings for hiking 
trails by drawing a symbol (e.g. yellow cross) on top of a background 
(white rectangle). I double-checked the OSM input file, all the 
background nodes are in the file before any of the symbol nodes.

In the output, the symbols are drawn correctly on top or hidden behind 
the white rectangles at random. The effect is the same in MapSource and 
on the device. The same symbol/background combinations are sometimes 
drawn properly and sometimes in reverse order.

I have attached two images showing the good and broken case on two 
neighboring nodes. From the tooltips in Mapsource you can see the 
inverted order of foreground and background in the broken case.

I have checked this with mkgmap r858 and r935, both with identical 
results. The last version this works completely is r590.

Ways seem to be ok, at least I could see no problems there during my 
first tests. Is it possible that the fix only applies to ways but not 
tod nodes?

bye

       Nop
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