David Arnold wrote:
> Hi,
>
> I confess I got some earlier advice on this issue, but I've never
> been able to apply it to find a resolution. In the buffer that
> follows, I define a clipping box:
>
> % clipping path
> path cpath;
> cpath:=(-5,-5)--(5,-5)--(5,5)--(-5,5)--cycle;
> cpath:=cpath scaled 1u;
>
> A function is created and scaled:
>
> % scale and draw graph
> P:=P scaled u;
> draw P withcolor blue;
>
> The picture is clipped and saved:
>
> % clip and save current picture
> picture pic;
> clip currentpicture to cpath;
> pic:=currentpicture;
>
> Then it is redrawn later.
>
> % redraw line
> draw pic;
>
> Unfortunately, even though this works, mathematicians really want
> arrows at each end of the graph. Easy enough to do with drawdblarrow
> P withcolor blue, but the arrows then get clipped. What I really need
> is to adapt the code below so that my function is clipped to the
> boundary box, but then redrawn with arrows at each end of it. If
> anyone can adjust my code to do that, it would be much appreciated,
> and it would break down a barrier I've faced for years with metapost
> coding.
>
> Note that I've tried some stuff with cutbefore and cutafter with some
> success. But I should remark that the code below is generated by a
> perl script and some special coding we've set up to generate these
> graphics on the fly for student quizzes. This is not a situation
> where I can tweak an individual plot or two. Rather, our script might
> generate 100 sets of the code below, all with different parameters.
> So this magnifies the problem.
>
as you sat, the basics are in:
P := (P cutbefore cpath) ;
P := (P cutafter cpath) ;
drawdblarrow P withcolor green;
it should not be too hard for a mathematician to make sure that this works ok;
i think that as long as one makes sure that the directions are right (do a
reverse P if needed)
Hans
-----------------------------------------------------------------
Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
| www.pragma-pod.nl
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