[GRASS5] Bug: vector maps shifted (d.area / d.vect)

Markus Neteler neteler at itc.it
Sun Oct 21 12:25:51 EDT 2001

On Sun, Oct 21, 2001 at 03:58:03PM +0200, Bernhard Reiter wrote:
> On Sun, Oct 21, 2001 at 01:55:33PM +0200, Markus Neteler wrote:
> > On Sat, Oct 20, 2001 at 12:44:41PM +0100, Glynn Clements wrote:
> > > If you remove the +0.5 from fastline(), d.vect and d.area coincide. 
> > > However, G_plot_line() is used in many places, so changing it to suit
> > > d.vect may break other things.
> > 
> > Thanks for looking into it. But I wouldn't call it "breaking things":
> > For 5.0 the display needs to be consistent in my opinion, we should
> > not accept map shifts. I am willing to search-and-fix, but need a
> > hint what route to follow.
> > 
> > Raster and vector overlays should be 100% o.k.
> Nobody will say no to this.
> On the other hand Glynn's comment is correct:
> Changing things in a core function which is used at various places
> is not a change you want todo between a pre2 and a final release.
> If this inconsistency was there for a long time other code might
> work around it in places you cannot easily see. Fixing it in the
> core fuction is very likely to break things at other places.
> Therefore you need to test it intensively.
> Not knowing the details of this case I recommend that adding a
> workaround to d.vect for the 5.0.0 release should be considered.
>    Bernhard

... maybe yes - of course we don't want to break the system now.
 - d.vect is right
 - d.area, v.area are wrong
according to d.rast (and my eyes). 
So we have to careful where to apply the work-around.


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