# Re: [NTG-context] Clipping a path to a boundary

```David Arnold wrote:

```
`Hans,`
```
I tried:

% redraw line
path q;
q:=pathpart pic;
drawdblarrow q withcolor blue;

```
But it drew the clipping path. I wanted the part of the path inside the clipping path.
```
Am I missing something in your directions?
```
```

ok, here's the full solution ...

\starttext

\setupcolors[state=start]

\startMPpage
vardef lastpath (expr p) =
save _p_ ; path _p_ ; _p_ := origin ;
for i within p :
if stroked i : _p_ := pathpart i ; fi ;
endfor ;
_p_
enddef ;
vardef firstpath (expr p) =
```
save _p_, _b_ ; path _p_ ; _p_ := origin ; boolean _b_ ; _b_ := false ;
```       for i within p :
```
if not _b_ : if stroked i : _b_ := true ; _p_ := pathpart i ; fi ; fi ;
```       endfor ;
_p_
enddef ;
```
picture pic; pic := image(
```       draw fullcircle scaled 5cm withpen pencircle scaled 5mm ;
draw fullsquare scaled 2cm withpen pencircle scaled 5mm ;
fill fullcircle scaled 1cm withpen pencircle scaled 5mm ;
) ;
```
draw pic ;
```   drawdblarrow lastpath (pic) withcolor blue ;
drawdblarrow firstpath(pic) withcolor red ;
\stopMPpage

\stoptext

...  suitable for submission to the wiki

```
```On Aug 7, 2005, at 2:56 PM, Hans Hagen wrote:

```
```David Arnold wrote:

```
```
```
This works fine. However, what I need to do is somehow clip the path P to the bounding box, but retain the resulting cutpath in a path variable Q. That is, I need to cut off the parts of the path P that lie outside the bounding box cpath:=(-5,-5)--(5,-5)--(5,5)--(-5,5)--cycle and store the clipped path in the path variable Q. The difficulty is I have no advance knowledge if the path P lies entirely inside the bounding box or if it escapes through one of the sides.
```

it all depends on what you want to do further on;
```
- you can do some cutbefore and cutafter trickery, i.e. determine intersectionpoints with the edges of the bbox and do some cutting
```
- if you just want the path back .. just ask for "pathpart pic"
Hans
-----------------------------------------------------------------
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
-----------------------------------------------------------------

_______________________________________________
ntg-context mailing list
ntg-context@ntg.nl
http://www.ntg.nl/mailman/listinfo/ntg-context

```
```
_______________________________________________
ntg-context mailing list
ntg-context@ntg.nl
http://www.ntg.nl/mailman/listinfo/ntg-context

```
```

--

-----------------------------------------------------------------