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[mkgmap-dev] Configurable flood blocker

From Felix Hartmann extremecarver at gmail.com on Sat Dec 18 19:20:10 GMT 2010

> Felix,
> there is nothing to check. The flood blocker works only in 
> multipolygon mode. It is not possible to implement that for the 
> polygon mode.
> Where do you think is the advantage of the polygon mode?
> WanMil
The advantage is:

a) Speed (if you use --transparent and then gmt to set the transparency 
to no) you can have for land one polygon (only land area) for sea one 
polygon (only sea area) and NO background polygon.
b) overlapping maps - using --transparent there is less chance that a 
land polygon from one map, overlaps sea from another map (on GPS as only 
there can be several maps active at the same time).

--- in principal there is no speed advantage - but only as long as one 
does not attribute a color to 0x4b, however as one colors the 
background/land to be say white, it is much quicker to have white land 
background only, otherwise the GPS has to read much more data, and on 
older generation GPS when panning the map, there is a notable speed 
difference on top of flahing up background color, until it is overdrawn 
by the real landuse/natural/... polygon.

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