Re: METAPOST: How do I get this 'max' cutafter to work?

[Gerben Wierda <gerben.wierda@rna.nl>]

> On 22 Apr 2020, at 09:30, Taco Hoekwater <taco@elvenkind.com> wrote:
> 
> Hi,
> 
>> On 21 Apr 2020, at 17:52, Gerben Wierda <Gerben.Wierda@rna.nl> wrote:
>> 
>>> pair a ; a := arrowHead intersection_point connection ;
> 
> Hans’ example also works with “intersectionpoint”: the differences between intersectionpoint
> and intersection_point are minimal except if there is no intersection at all.
> 
> The trick is that Hans does not use cutafter. cutafter is designed to cut off as little as 
> possible, it is a cutbefore on both paths reversed. So, uses the last intersection point of 
> the paths, and in this case it will therefore use the top of the arrowhead. 
> 
> In contrast, intersectionpoint finds the first intersection on the non-reversed paths, which 
> is the base of the arrowhead.
> 
> Alternatively (in this case), you could move the arrowhead up a tiny amount, so that there is 
> only one intersection between the connection and arrowHead.

In fact I did something like this, except that I first shortened the line path so it ends in the middle of the triangle before doing a cutafter (twice in both directions and taking the one which cuts the most). This works reliably.

I gave up on another approach (which repeatedly cut a little bit from the path until it wasn’t intersecting anymore, then taking the one form thelast successful intersection)  as I also have paths that connect a path-cycle to itself. A ‘cut until it just doesn’t intersect anymore' would eat up the entire path in that case until only a single point is left.

G

> 
> Best wishes,
> Taco
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