> On Aug 2, 2016, at 4:04 PM, (Asad) Syed, Asadullah Hussain
> <asadullah.huss...@tum.de> wrote:
>
> Hi, I want to programmatically extract top level objects for a g file (the
> ones you get when “tops” command is issued in mged). According to the
> definition top level objects are the ones which aren’t referenced by any
> other combination. Looking at the ged_tops function I deduced that the only
> check is to see if “dp->d_nref == 0”, where dp is a “struct directory”
> pointer.
>
> But the problem that I have is that all objects seem to have dp->d_nref==0
> and even when I use db_ls using “DB_LS_TOPS” flag still I get ALL objects.
> Am I missing something?
Yes, as that’s a potentially unnecessary and sometimes expensive calculation,
so it doesn’t get computed automatically. You have to call db_update_nref().
See libged/tops.c:84.
That said, probably a better way than calculating tops yourself is to call
db_ls(). Here’s a functioning example*:
int main(void) {
struct db_i *dbip = db_open("test.g", DB_OPEN_READONLY);
struct directory **tops;
db_dirbuild(dbip);
int count = db_ls(dbip, DB_LS_TOPS, NULL, &tops);
bu_log("found %d top level objects\n", count);
while (count > 0) {
bu_log("top path is %s\n", tops[count-1]->d_namep);
count--;
}
if (tops)
bu_free(tops, "free tops");
return 0;
}
Cheers!
Sean
* note this is a quick example that assumes c99
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