[Marble-devel] GroundLayer

[Torsten Rahn]

If you have a map theme that purely consists of vector data then the 
vector data might not provide the background itself being rendered.

The groundlayer provides just that: a filled background color.

We needed it for two reasons:

- In the Natural Earth  Vector rendering GSoC project we want to replace the 
ancient VectorComposer/VectorMap API by full GeoPainter / GeoData rendering. 
There the source data (shape files) don't define a common background color. 
Instead the color is specified by the dgml document. It has been like that for 
our current Plain Map but there the blue ocean ("ground") gets painted by 
VectorComposer::paintBase() (?).

- And the Vector Tiles used in our current OSM Vector Tile GSoC project also 
don't provide rendering information for the ocean / land.

So in order to end up with a "transparent" background we have the ground layer 
now.

For all maps that use bitmap data the groundlayer is simply not rendered at 
all since it's not needed. 

BR,
Torsten 



On Donnerstag, 2. August 2012 14:01:11 Konrad Enzensberger wrote:
> Hello,
> 
> can one of you explain me for what the new GroundLayer is for
> and how this layer should be used ?
> 
> br, konrad