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From: Pierre de Mouveaux <pmx@audiovu.com>
Reply-To: pmx@audiovu.com
To: Markus Neteler <neteler@geog.uni-hannover.de>
Subject: Layered driver
Date: Wed, 3 May 2000 16:39:46 +0200
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Hello Makus,

First, are you sure that the new layered driver  has replaced the standar=
d=20
driver?=20

If so, then here's a short tutorial ;))))

When opening a driver, you begin with layer '0' (the bottom).

select an other layer: (layer 1, that is over layer 0).=20
d.layers -t l=3D1

At this point, the current target layer is '1'.=20
d.vect realnutz96=20
The vector map is drawn. Nothings special ... at first glance.

then, add a raster in the bottom of the map:

d.layers -t l=3D0
d.rast dgm25 =20

Magic there: it draws *under* the vector map!

At this point, the "cuuent layer" is again layer '0' that we just selecte=
d.

Now, some exercises... to hide the vector map

d.layers -h l=3D1
then, to "solo" the vector map
d.layers -o l=3D1

to solo the raster map, that's the current map, we can ommit the layer=3D=
 option
d.layers -o

to redraw all layers:
d.layers -a.

To erase the current layer

d.layers -x=20
 ... ;) doesn't work! For security, you are required to supply the layer =
id !
so=20
d.layers -x l=3D0

You have only the vector map.

And to confirm that the currnt layer is the layer '0', you just type

d.layers -g

=20
I tried a "transparency" layer. I did it like a xxx (my english vocabular=
y is
not rich enough ;). It's very slow. But it works. The slow part is an
incredible time I spent into one XLib function that lookup colors.=20

PS I'm  reading  the New grass programmers manual 5.0.

I will send you my first impressions. Sure, it's a really needed work you=
 do!!!

Bye,
Pierre.