[mkgmap-dev] PATCH v2: highwayCount

Fri Feb 22 12:10:32 GMT 2013

Hi

> When I change mkgmap to add a different type as background (e.g. 0x50 for
> forest),
> long distance routing is more or less surely broken.

OK good, I tried exactly the same thing yesterday, but MapSource
wouldn't start up with the resulting map.

> Up to now, --transparent changes two things:
> 1) it sets a bit in the TRE header file
> 2) it avoids to create the backgroud polygon(s) with type 0x4b

If no idea what the TRE header bit actually does.

Polygons are opaque, so you need a polygon that covers the whole map,
the 0x4b is the standard way of doing this, but other ones work
for that purpose.

> I am not sure if 2) is needed to get a transparent map. Attached is a small
> patch that
> changes mkgmap so that it always generates the background polygon.

My believe was that transparent maps were for contour lines or POI and
similar uses. In these cases routing is not important, so I'm not
really concerned unless we are doing something wrong.

> If that doesn't work, another possible solution would be to
> disallow--transparent in combination
> with --route. I assume that would require to have the --transparent flag for
> all other layers?

Normally you would have an opaque map at the bottom and one or more
transparent maps on top. Routing should happen normally on the
bottom map.

..Steve