[Qgis-developer] GRASS Direct

[Radim Blazek]

The GRASS Direct is an environment developed within QGIS GRASS
plugin/provider which makes it possible to run GRASS raster modules
without GRASS mapset and without data conversion to GRASS format.
Basically it is a library implementing GRASS data read/write function
which is using QGIS providers to read/write data. In direct mode, the
GRASS modules are run with this library instead of  the standard GRASS
gis library.

The GRASS modules may be run in direct mode from GRASS Tools (which
are now always enabled) if no mapset is opened. The interface is
similar to the standard GRASS Tools apart that the region is selected
in combo box in top of options (to be discussed) and the output is a
GeoTIFF file. It is also possible to run GRASS modules in direct mode
from a shell if some environment variables are set. You can see those
variables printed in top of the output tab.

This is work in progress, so I was reluctant to announce that but
because it had caused some compilation problems, it was necessary to
explain a bit how it works. Currently there are only few modules
enabled and you can find various problems. Especially it was only
tested on Linux and most probably more fixes will be necessary on Mac
and Windows.

I believe that GRASS Direct could also be used in SEXTANTE with a
little work. It would be necessary however to distinguish modules
which may be run in direct mode from those which may not (mostly
vector modules).

Sorry for the problems I caused on Mac and Windows and many thanks to
Jürgen and Larry for fixes.

Radim