[GRASSLIST:6733] Re: symbols and map units

[Hamish]

> > > I am trying to create a symbol and display it in scale
> > > corresponding  with map units.
> 
> > perhaps try v.buffer and ps.map's vareas.
> 
> yes, but I would like to display special symbols (for cadastral maps),
> not only circles... I don't understand relation between BOX (larger
> side) and symbol scaling (in map units). So I am not sure if it is
> possible to find relation between size of symbols and map units...

the icons are not tied to map units. zoom way in or way out they stay
the same size relative to the display monitor.

some hacking of the ps.map code might change this for you.

also try the embedded postscript (eps) symbol support in ps.map.

maybe someone else knows a solution.



> BTW, how to display part of circle (ARC) (90deg->270deg clockwise).
> 
>     ARC 0.25 0.75 0.75 90 270 works
> 
>     I need ARC 0.25 0.75 0.75 90 270 C (or ARC 0.25 0.75 0.75 270 90)
>     -> I get only line...


If you try and draw the arc backwards then only the start/end points are
connected. Switching the order of the angles or adding "C" should make
it draw.

are you trying for something like this? 
 ____
 \__/

ARC 7 7 3 180 360

So just switch the order of the numbers or add a "C" to the end of the
line.

that "ARC x y r 360 180" draws only a line is probably a bug?


Note degrees are polar theta not navigational, i.e. 0 is east and values
increase counter-clockwise from there. Reducing the angle from a full
circle does not make it draw like a pacman but rather with a straight
chord-line from the start/end points on the circle as defined by the two
angles.



Hamish