[GRASS5] g51: v.out.ogr compilation

[Glynn Clements]

Piero wrote:

> when compiling g51 I have the following messages:

> OBJ.i686-pc-linux-gnu/main.o: In function `main':
> /home/piero/unst_g/grass51_exp_2002_11_15/vector/v.out.ogr/main.c:145: 
> */undefined reference to `OGRRegisterAll' /*

> As you see the module is compiled, but it is not linked in grass51 (if 
> linked is the correct term). (I have grass51 in the bin.arch dir, it 
> runs, but v.out.ogr doesn't works).
> I tried to watch  in the Makefile (that specific for the module and 
> those in the upper dirs) but I don't fully understand
> them (or I don't understand anything, this is a point of view). For 
> example, in the Makefile for the module, It's  used the GDALCFLAGS 
> variable. In Platform.make I have:
> 
> #GDAL
> GDALLIBS            = -ldl
> GDALCFLAGS     =
> 
> Pheraps I have compiled GDAL without the GRASS support, however what 
> GDALCFLAGS represent ? It goes to EXTRA_CFLAGS so should it used to 
> specify additional include dirs ? (I have gdal in a standard dir 
> (specified both in /etc/ld.so.conf end in my ~/.bashrc), so probable 
> it's correct that the field is empty).
> If I configure gdal --with-grass=ARG  (ARG=no or libgrass path) what 
> does libgrass mean? (libgrass5 doesn't exist!).
> (Perhaps  this option is for other (than GRASS) program that must use 
> GDAL and GRASS utilities?)

1. You don't need to build GDAL with GRASS support.

2. I suspect that you do need to use "configure ... --with-gdal".

Basically, there are two ways in which the GDAL library can be used;
it can either be linked against directly during the build process, or
it can be dynamically loaded at run-time using dlopen() (this is the
mechanism which programs typically use for "plugins").

If you use the --with-gdal configure switch, it will be linked
directly, otherwise it will be dynamically loaded. However, it appears
that v.out.ogr doesn't support the dynamic loading mechanism (in
GRASS5, the only program which uses GDAL is r.in.gdal, which supports
both methods).

I suggest trying "configure ... --with-gdal"; that should result in
something similar to the following in Platform.make:

	GDAL_LIBS           = -lgdal.1.1
	GDAL_CFLAGS         = -DUSE_GDAL_H

If you still have problems with v.out.ogr when using --with-gdal, let
us know.

-- 
Glynn Clements <glynn.clements at virgin.net>