Re: what is nxy?

[Hans Hagen <pragma@wxs.nl>]

At 10:41 PM 10/18/00 +0200, Denis B. Roegel wrote:
>If I go back to the example of an earlier question of mine,
>I see that
>
>  1) I don't understand what `nxy' is; as far as I can see,
>     it is not explained in the metafun manual;
>  2) I don't understand why the connection between the first
>     and the second word goes from center to center, 
>     and this may have something to do with 1).

>\startMPpositiongraphic{mypos:line}
>  path pa, pb, pab ; numeric na, nb;
>  initialize_box(\MPpos{\MPvar{from}});
>  na := nxy ; pa := llxy..lrxy..urxy..ulxy..cycle ;

The initialize_box macro sets a bunch of vars [still to be explained in
this chapter btw] and nxy is the pagenumber associates with the pos. 

>  initialize_box(\MPpos{\MPvar{to}});
>  nb := nxy ; pb := llxy..lrxy..urxy..ulxy..cycle ;
>  if na=nb :

So, we only draw a graphic when both positions are on the same page. [i do
have an alternative that handles multiple pages]. In the background graphic
that goes behind the text [area] this page number info is used to let the
background cross the page. 

Concerning (2): the "center" directive makes that happen 

Hans
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