[GRASS-dev] Building a vector topology (and failing)

[Martin Landa]

2012/3/12 Seth Price <seth at pricepages.org>:
> Hey all, I've been trying to get my topology to build for a while now in my
> module, and I'm not getting anywhere. I currently have it to the point where
> I'm simply trying to draw a triangle with corners (0,0), (0,100), & (100,0).
> It calls Vect_append_point() three times,

a valid area is defined by a closed boundary or by (closed) chain of
boundaries. In this case simply add the last point at 0,0.

> then Vect_write_line(,GV_BOUNDARY,,) to create the polygon. When building
> the topology, it fails to create an area with "WARNING: Number of incorrect
> boundaries: 1".

yes, there is one boundary which cannot form an area (it's not closed).

Martin

-- 
Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa