2014-05-02 17:23 GMT+02:00 Pieren <[email protected]>: > On Fri, May 2, 2014 at 4:41 PM, John F. Eldredge <[email protected]> > wrote: > > Layer = -1 is not valid data for a waterway that is on the surface, > which by definition is layer 0. It is only valid data on an underground > waterway. > > Pfff, Martin, why did you restart this thread ? >
sorry, came back from holidays and didn't see that is was already a week old. ;-) > Water is always below the ground, otherwise it's a flood ;-) nope, waterways are almost always on the ground (surface water, french: eaux superficielles), otherwise it is groundwater (french eau souterraine). Rivers, streams, canals etc. are generally surface water. Anyway, this has nothing to do with the layer tag. I believe it was already said ~5 times this year on this list, but some repetition won't harm: if no explicit layer tag is set an object is supposed to be on layer=0, but this has nothing to do with underground vs. on the ground. The layer tags define stacking locally, i.e. when several objects overlap (in 2D) a different layer tag indicates that this is not happening in the same layer, but that one object is above the other, the higher the layer number the higher the object. Objects at the same spot on the same layer do intersect/overlap. This has also nothing to do with tagging for the rendering, it is a rough representation of 3-dimensional objects in a 2,5D space. When rendering you can use the layers as rendering order, but you do not have to, often you will decide to draw lower features above higher ones in order to make them visible. cheers, Martin
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