On 18/09/18 21:23, Henri Menke wrote:
> On 9/18/18 7:57 PM, Hans Hagen wrote:
>> On 9/16/2018 10:28 AM, Henri Menke wrote:
>>> Dear list,
>>>
>>> I want to draw paths between points which are bent by a certain angle.
>>> The code in the MWE below works well but I was thinking that the expert
>>> here can surely improve it and suggest a nicer syntax.
>> looks like a challenge for Alan ... isn't it also a bit 3d (2.5d)?
>
> I wasn't thinking about a 3D application here, just a little bend on the
> path to go around other elements in my drawing without having to think
> about explicit control points (like the second example in my original
> post). In the meantime I have improved the defintion of the macro to
> avoid double computation of the angle:
>
> vardef bend(expr a,b,phi) =
> save x ;
> x := angle(b-a) ;
> a{dir(x+phi)} .. {dir(x-phi)}b
> enddef ;
>
> So currently the applied syntax is
>
> drawarrow bend(z1, z2, 30) ;
>
> However, I would prefer something like
>
> drawarrow z1 bend(30) z2 ;
>
> I'm not sure whether this is possible though. Actually I'm reading the
> MetaPost manual right know because my MP skills are rather poor.
I think I got it now. Not sure whether “bend” should be primary or
something else.
\startMPdefinitions
primarydef a bend phi =
do_bend(a,phi)
enddef ;
vardef do_bend(expr a, phi) expr b =
save x ;
x := angle(b-a) ;
a{dir(x+phi)} .. {dir(x-phi)}b
enddef ;
\stopMPdefinitions
\starttext
\startMPpage
z1 = (-.5cm,1cm) ;
z2 = (1cm,3cm) ;
for phi = 0 step 5 until 360:
draw z1 bend(phi) z2 withcolor (phi/360)[red,blue] ;
endfor ;
\stopMPpage
% Possible use case:
\startMPpage[offset=1cm]
z1 = (-.5cm,1cm) ;
z2 = (1cm,3cm) ;
draw z1 -- z2 ;
dotlabel.lft("$-$", z1) ;
dotlabel.lft("$+$", z2) ;
path p; p := z1 bend(-30) z2 ;
drawdblarrow p withcolor blue ;
label.lrt(textext("$\Delta$"),point .5 along p) withcolor blue ;
\stopMPpage
\stoptext
>
>>
>> -----------------------------------------------------------------
>> Hans Hagen | PRAGMA ADE
>> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>> tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
>> -----------------------------------------------------------------
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