On 2012-05-02 Alan BRASLAU <alan.bras...@cea.fr> wrote:

> For  example, in  the minimal  example below,  how can  one obtain
> a  transparent  arrow  without  getting an  X-ray  vision  of  the
> arrowhead?

Maybe I'm  reinventing the  wheel here,  but you  can write  a small
macro that only draws the lines you want. Here is an idea:


        linecap  := squared;
        penscale := .5bp;
        pickup pencircle scaled penscale;

        def drawmyarrow expr p = _apth:=p; _myfinarr enddef;
        def _myfinarr text t =
                draw _apth cutafter point (-ahlength+.1penscale) on _apth t;
                fill arrowhead _apth  t

        drawarrow   origin    -- (1cm,0)     withtransparency(1,.5) ;
        drawarrow   origin    -- (0,1cm)     withtransparency(1,.5) ;
        drawmyarrow (1.5cm,0) -- (2.5cm,0)   withtransparency(1,.5) ;
        drawmyarrow (1.5cm,0) -- (1.5cm,1cm) withtransparency(1,.5) ;


The (-ahlength+.1penscale)  are of  course empiric. You  should find
the correct  formula to always have  a nice match of  line and arrow
whatever ahlength and ahangle values are in use.


If your question is of interest to others as well, please add an entry to the 

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net

Reply via email to