[GRASS5] [bug #3704] (grass) d.rast.arrow does not save a line in the monitor history

[Daniel Calvelo Aros]

From: Hamish <hamish_nospam at yahoo.com>
Sent: Wed, 12 Oct 2005 19:05:02 +1300
> 
> Done & in CVS.
> 
> d.rast.arrow now can take a raster map for arrow magnitude and there 
> is a new skip option to only draw arrows every Nth cell.
> 
> screenshot showing raster elevation level, with arrow direction and size
> controlled by aspect and slope maps (created with r.slope.aspect); skip
> factor set to only draw every third cell; and grid color set to "none":
> 
>   http://bambi.otago.ac.nz/hamish/grass/d_rast_arrow_magnitude.png
> 
> The question remains what to do if fed negative magnitudes. Right 
> now I have it skipping over that arrow (as it does for NULL values), 
> but it could take the absolute value or rotate the arrow 180 degrees.

I'd say keep the current skip, but issue a warning; whatever the cartographer
needs to do he can using r.mapcalc (tell him in the warning and the docs).

The other possibility is to add an option, but I've the impression it somehow
reduces flexibility...

Daniel.