[mkgmap-dev] [PATCH v1] - provide alternative sea drawing mechanism

Wed Dec 30 19:21:17 GMT 2009


Mark Burton wrote:
> Firstly, I would like to thank everyone who responded to my
> "Understanding the sea" post. From those posts and my own study, I
> finally worked out what it does. And yes, it works pretty well inasmuch
> that it generates some useful polygons. The "sea sector" heuristic
> doesn't work for me so I have been disabling it.
> 
> The problem is, the end result is "butt ugly". Our MP implementation
> really can't do a good job on zillions of little islands. 
> 
> After frigging around for a couple of days trying to improve the
> visual quality, I tried the obvious alternative technique of not using
> a MP but, instead, just having a sea background and then put the land
> on top using plain polygons. Guess what? It works very nicely as the
> attached pics show. I now have a splendid map of the Baltic area (OK
> it's weird at the edges but that's not a problem for now).
> 
> Here's the (future) commit comment for this patch:
> 
>     Provide an alternative to using a multipolygon when generating the sea.
>     
>     The --generate-sea option can now take a comma separated list of values:
>     
>     no-mp - don't generate the sea using a multipolygon - instead, generate
>     a background sea polygon and then individual land polygons with tag
>     natural=land. This requires a suitable land polygon type to be defined
>     in the style file (suggested type is 0x010100) and the polygon must be
>     defined in the TYP file as having a higher drawing level than the sea
>     polygon type.
>     
>     no-sea-sectors - disable the generation of "sea sectors" when the
>     coastline fails to reach the tile's boundary.
>     
>     With no values specified, the --generate-sea option should work as
>     before.
> 
> Oh yes, this patch doesn't include it, but I am also disabling the DP
> code for polygons as it makes them weird.
> 
> Cheers and thanks again for the helpful postings.
> 
> Mark
> 
Hurrah! Does this also mean that, with suitable definition of the 
polygon used for land, we can finally banish the "Garmin yellow" 
background to history?


-- 

Charlie