Hi, would it be an option for you to do
newcircleA := circleA cutbefore P1 cutafter P2 -- cycle ; In that case you avoid extra points. /Mikael On Mon, Dec 20, 2021 at 5:30 AM Fabrice L via ntg-context <[email protected]> wrote: > > Dear list, > > I have a problem connecting path with the operator « & » (page 16 Metafun > manual). The problem is illustrated by the code (and the joined PDF) which > follows. > > I draw random cycled forms (left part of the figure) and when they interact, > they are modified to « fit together » (right part of the figure) . When > building these new forms, I connect paths (usually two or three depending on > position 0 of the path); the last point a path is the same as the first point > of the next path ; for exemple, to modify the blue circle, named « circleA », > I take the circle A from P1 to P2, then a segment from P2 to P1 and cycle to > have a closed path. So I should be able to do : > > newcircleA := circleA cutbefore P1 cutafter P2 & (P2 -- P1) & cycle ; > > The « & » operator is supposed to work (if I understand correctly) in this > case, but I have this error message : > > "! Paths don't touch; `&' will be changed to `..’." > > Which I do not understand since the paths « touch ». There was a similar > question last year, without a clear answer (« > METAPOST subpath rounding issue > »https://www.mail-archive.com/[email protected]/msg94294.html). > > A solution is to ignore the repeating points : > newcircleA := circleA cutbefore P1 cutafter P2 -- (P2 -- P1) -- cycle ; > but this new shape has 9 points instead of 7. The problem is that I do these > operations a number of times, and the length of a path (in the number of > points) is increasing and cause trouble when I look for intersections with > others shapes. > > Here is the MWE: > > \startMPpage > path circleA , circleB ; > pair P[]; > > circleA := fullcircle scaled 1in randomized 3 ; > circleB := fullcircle scaled 1in randomized 3 shifted(0.3in,0.3in) ; > > draw circleA withcolor blue ; > draw circleB withcolor red ; > > P[1] := circleA intersectionpoint circleB ; > dotlabel.lft("$P_1$",P[1]) ; > dotlabel.rt("$\blue\tfx P_0^A$",point 0 of circleA) ; > P[2] := reverse(circleA) intersectionpoint circleB ; > dotlabel.rt("$P_2$",P[2]) ; > dotlabel.rt("$\red\tfx P_0^B$",point 0 of circleB) ; > > path newcircleA , newcircleB ; > % newcircleA := circleA cutbefore P1 cutafter P2 & (P2 -- P1) & cycle ; > % previous line gives an error : > % "! Paths don't touch; `&' will be changed to `..'." > newcircleA := circleA cutbefore P1 cutafter P2 -- (P2 -- P1) -- cycle ; > newcircleA := newcircleA xshifted 2in ; > draw newcircleA withcolor darkgreen ; > > newcircleB := (circleB cutafter P1) -- (P1 -- P2) -- (circleB cutbefore P2 ) > & cycle ; > newcircleB := newcircleB xshifted 2in ; > draw newcircleB withcolor black ; > drawpoints newcircleA ; drawpointlabels newcircleA ; > > \stopMPpage > > > > > I would appreciate any help ! Thanks ! > Fabrice. > > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___________________________________________________________________________________
