[GRASS-dev] Principle G3D library question

[Markus Metz]

On Tue, Jun 21, 2011 at 1:58 PM, Maris Nartiss <maris.gis at gmail.com> wrote:
> I would suggest to change grass7 to something not GRASS release dependent.
>
See [0] and following lines for an example of file format versioning
independent of the release

[0] https://trac.osgeo.org/grass/browser/grass/trunk/include/vect/dig_defines.h#L151

Silently following the thread,

Markus M


> just my 0.02,
> Maris.
>
> 2011/6/21 Soeren Gebbert <soerengebbert at googlemail.com>:
>> Hi Maris,
>> the new rater3d ascii header looks like this now:
>>
>> version: grass7
>> order: nsbt
>> north: 80.000000
>> south: 0.000000
>> east: 120.000000
>> west: 0.000000
>> top: 50.000000
>> bottom: 0.000000
>> rows: 8
>> cols: 12
>> levels: 5
>>
>> The options "version" and "order" are introduced with my changes on
>> the g3d library in grass7. The manual page of the svn version of
>> r3.out.ascii in grass7 explains a bit more.
>>
>> Best regards
>> Soeren
>>
>> 2011/6/21 Maris Nartiss <maris.gis at gmail.com>:
>>> (Still haven't looked at code) - I hope GRASS7 files will have a
>>> version number in header to be future-proof.
>>>
>>> Maris.
>>>
>>> 2011/6/21 Soeren Gebbert <soerengebbert at googlemail.com>:
>>>> Hi Maris,
>>>>
>>>> 2011/6/21 Maris Nartiss <maris.gis at gmail.com>:
>>>>> Hello,
>>>>> It's not an backporting of header it's about GRASS6 being able to
>>>>> distinguish GRASS7 format g3d files. I have not peaked into code if
>>>>> there such feature exists. If not, it should be implemented to prevent
>>>>> GRASS6 failures (or worse - data corruption) on GRASS7 files.
>>>>
>>>> I see, good point!
>>>>
>>>> The grass6 implementation checks for valid header:
>>>>
>>>> static void readHeaderString(FILE * fp, char *valueString, double *value)
>>>> {
>>>>    static char format[100];
>>>>
>>>>    /* to avoid buffer overflows we use snprintf */
>>>>    G_snprintf(format, 100, "%s %%lf", valueString);
>>>>    if (fscanf(fp, format, value) != 1) {
>>>>        G_debug(0, "bad value for [%s]", valueString);
>>>>        fatalError("readHeaderString: header value invalid");
>>>>    }
>>>>    while (fgetc(fp) != '\n') ;
>>>> }
>>>>
>>>> I think this should prevent the import of new grass7 volume ascii
>>>> files in grass6. The grass6 import will break in when the new lines of
>>>> the grass7 header are parsed.
>>>>
>>>> Best regards
>>>> Soeren
>>>>
>>>
>>
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