[GRASS5] vector format last change

Radim Blazek blazek at itc.it
Thu Jan 16 04:06:50 EST 2003


I want to make (hopefully) last change in GRASS 51 vector format.
Please comment this if you want so that we can make it realy _last_
change and stabilize the format. I am using current version for
about one year (sidx added this summer) for development and some real work 
without problems, proposed changes are either cosmetics (header length),
or fields reserved for future 3d volumes.

Proposed changes:
Immediately after version and byte order write header size.

Do not write reserved (not used) bytes in header.
Define new types:
#define GV_FACE       0x10   (in modules)
#define GV_KERNEL     0x20
#define GV_STORE_FACE   5    (used in file/tables)
face is 3D equivalent of boundary and kernel is 3D equivalent of centroid.
Volumes will not be supported for some time, but faces are useful for
displaying vertical planes (walls) in nviz.
Add to header:
n_flines, n_klines (faces and kernels),
n_edges (reserved, edge will be 3D equivalent of node, line shared between 
n_volumes, n_holes (reserved volumes and holes will be built from faces and 
Edge_offset, Volume_offset, Hole_offset (reserved for future).
In 3D file add to node structure n_edges, for now will be 0, because even if
faces are present volumes are not built.
Add to header
Edge_spidx_offset, Volume_spidx_offset, Hole_spidx_offset
For format postgis replace HOST, PORT, DATABASE, USER, PASSWORD by DATABASE
only which may be db name or string in form "host=xx,dbname=xx,user=xx",
it will be the same as used in DB file and by db.connect (pg driver).


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