On Sat, 22 Sep 2018 13:45:17 +0200 Hans Hagen <j.ha...@xs4all.nl> wrote:
> On 9/22/2018 12:08 PM, Floris van Manen wrote: > > It does not seem to work for all character combinations. > > e.g. B&T works, C&T works, C&M works, but N&T does not work. > > not N&M > > Why would that be? > > Thanks > > .Floris > > > > > > > > > >> On 22 Sep 2018, at 11:27, Hans Hagen <j.ha...@xs4all.nl > >> <mailto:j.ha...@xs4all.nl>> wrote: > >> > >> On 9/22/2018 10:35 AM, Henri Menke wrote: > >>> Dear list, > >>> Challanged by a very old TeX.SX question > >>> https://tex.stackexchange.com/questions/180510 > >>> I wanted to calculate all the intersection points between two > >>> characters. Therefore I ripped off the \showshape macro to load the > >>> outlines from the font and convert them to MetaPost paths. Then I try > >>> to find all intersections by cutting the path. > >>> It somewhat works but for some reason, in the MWE below two intersection > >>> points are missing. I also have the feeling that my implementation is > >>> extremely inefficient. I would very much appreciate some hints by the > >>> MetaPost experts! > >>> Cheers, Henri > >>> --- > >>> \startluacode > >>> -- That's a simple reimplemetation of the showshape macro > >>> function outlinepaths(character) > >>> local fontid = font.current() > >>> local shapedata = fonts.hashes.shapes[fontid] -- by index > >>> local chardata = fonts.hashes.characters[fontid] -- by unicode > >>> local shapeglyphs = shapedata.glyphs or { } > >>> character = utf.byte(character) > >>> local c = chardata[character] > >>> if c then > >>> if not c.index then > >>> return {} > >>> end > >>> local glyph = shapeglyphs[c.index] > >>> if glyph and (glyph.segments or glyph.sequence) then > >>> local units = shapedata.units or 1000 > >>> local factor = 100/units > >>> local paths = fonts.metapost.paths(glyph,factor) > >>> return paths > >>> end > >>> end > >>> end > >>> \stopluacode > >>> \def\mpdefineoutlines#1#2{\ctxlua{ > >>> local char = "\luaescapestring{#1}" > >>> local outlines = outlinepaths("#2") > >>> local len = \letterhash outlines > >>> tex.print("path " .. char .. "[];") > >>> tex.print(char .. "n := " .. len .. ";") > >>> for i, path in ipairs(outlines) do > >>> tex.print(char .. "[" .. i .. "] := " .. path .. ";") > >>> end > >>> }} > >>> \starttext > >>> \startMPpage > >>> pair shift; shift := (1cm,-1cm); > >>> numeric angle; angle := 5; > >>> \mpdefineoutlines{B}{B} > >>> \mpdefineoutlines{T}{T} > >>> nofill B2; > >>> nofill B3; > >>> eofill B1 withcolor .5[blue,white]; > >>> fill T1 shifted (shift) rotated (angle) withcolor .5[red,white]; > >>> path r; > >>> numeric n; n := 0; > >>> for i = 1 upto Bn: > >>> for j = 1 upto Tn: > >>> r := B[i]; > >>> forever: > >>> pair q; > >>> r := r cutbefore (T[j] shifted (shift) rotated (angle)); > >>> exitif length cuttings = 0; > >>> r := subpath(epsilon, length r) of r; > >>> q = point 0 of r; > >>> n := n + 1; > >>> dotlabel.urt(textext("\tfx" & decimal n), q); > >>> endfor; > >>> endfor ; > >>> endfor ; > >>> \stopMPpage > >>> \stoptext > >> > >> You migh find more when you go top double mode .. anyway, these > >> intersection calculations are not that accurate so you normally need > >> to apply some overkill. > >> > >> - a bit cleaned up outlinepath function > >> - use document namespace > >> - add helper for defineoutline > >> - do 4 runs over the shapes (probably too many now) > >> - more neutral fill code > >> > >> It makes a nice example for the metafun (although then I'd do it > >> slightly different). We need some rounding becaus eotherwise you get > >> similar points (you can add a message(q) someplace). > >> > >> \startluacode > >> > >> function document.outlinepaths(character) > >> local chardata = fonts.hashes.characters[true] -- by unicode > >> local shapedata = fonts.hashes.shapes[true] -- by index > >> local c = chardata[character] > >> if c and c.index and shapedata then > >> local shapeglyphs = shapedata.glyphs or { } > >> local glyph = shapeglyphs[c.index] > >> if glyph and (glyph.segments or glyph.sequence) then > >> local units = shapedata.units or 1000 > >> local factor = 100/units > >> return fonts.metapost.paths(glyph,factor) > >> end > >> end > >> return { } > >> end > >> > >> function document.defineoutline(char,target) > >> local outlines = document.outlinepaths(char) > >> local nofpaths = #outlines > >> context("path %s[] ;",target) > >> context("numeric %sn ; %sn := %s ;",target,target,nofpaths) > >> for i=1,nofpaths do > >> context("%s[%i] := %s ; ",target,i,outlines[i]) > >> end > >> end > >> \stopluacode > >> > >> \def\mpdefineoutlines#1#2{\ctxlua{document.defineoutline(\number`#1,"#2")}} > >> > >> \starttext > >> > >> \startMPpage > >> pair shift ; shift := (1cm,-1cm); > >> numeric angle ; angle := 5; > >> > >> \mpdefineoutlines{B}{B} > >> \mpdefineoutlines{T}{T} > >> > >> for i=1 upto Bn - 1 : nofill B[i] ; endfor ; > >> eofill B[Bn] withcolor .5[blue,white] ; > >> > >> for i=1 upto Tn : > >> T[i] := T[i] shifted shift rotated angle ; > >> endfor ; > >> > >> for i=1 upto Tn - 1 : nofill T[i] ; endfor ; > >> eofill T[Tn] withcolor .5[red,white] ; > >> > >> pair found[] ; > >> boolean isnew ; > >> numeric n ; n := 0 ; > >> pair rq ; > >> > >> def GoForIt(expr how) = > >> path r ; > >> for i = 1 upto Bn : > >> for j = 1 upto Tn : > >> r := B[i] ; > >> forever: > >> pair q ; > >> if how = 1 : > >> r := r cutbefore T[j] ; > >> elseif how = 2 : > >> r := r cutbefore reverse T[j] ; > >> elseif how = 3 : > >> r := reverse r cutbefore T[j] ; > >> else : > >> r := reverse r cutbefore reverse T[j] ; > >> fi ; > >> exitif length cuttings = 0 ; > >> r := subpath(epsilon, length r) of r ; > >> q = point 0 of r ; > >> isnew := true ; > >> rq := round(q); > >> for f=1 upto n : > >> if found[f] = rq : > >> isnew := false ; > >> exitif true ; > >> fi ; > >> endfor ; > >> if isnew : > >> n := n + 1 ; > >> drawdot q withpen pencircle scaled 4 ; > >> draw textext("\strut\ttbf " & decimal n) ysized 3 > >> shifted q withcolor white ; > >> found[n] := rq ; > >> fi ; > >> endfor; > >> endfor ; > >> endfor ; > >> enddef ; > >> > >> for i=1 upto 4 : GoForIt(i) ; endfor ; > >> > >> \stopMPpage > >> > >> \stoptext > Ok, a different approach then (probably still not all points as we need > to loop over segments but better) .. no more time now. > > It also shows that we don't need lua/tex juggling as we already can have > the paths in mp. (For sure now someone can complain that this is not > well documented.) > > \starttext > > \startMPdefinitions > > % will be added to metafun: > > def filloutlinetext(expr o) = > draw image ( > save n, m ; numeric n, m ; n := m := 0 ; > for i within o : > n := n + 1 ; > endfor ; > for i within o : > m := m + 1 ; > if n = m : > eofill > else : > nofill > fi pathpart i ; > endfor ; > ) > enddef ; > > def drawoutlinetext(expr o) = > draw image ( > % nicer for properties > for i within o : > draw pathpart i ; > endfor ; > ) > enddef ; > > def outlinetexttopath(text o, p, n) = > scantokens("numeric " & str n & ";") ; > scantokens("path " & str p & "[];") ; > n := 0 ; > for i within o : p[incr(n)] := pathpart i ; endfor ; > enddef ; > > \stopMPdefinitions > > \startMPdefinitions > > % outlinetexttopath(Bo)(B)(Bn) ; > % > % Bn := listsize(T) > > def showoverlapinoutlines(expr first, second) = > > path p_i, p_j, s_i, s_j ; > numeric n_i, n_j, index ; > pair found ; > index := 0 ; > for i within first : > for j within second : > p_i := pathpart i ; n_i := length(p_i) ; > p_j := pathpart j ; n_j := length(p_j) ; > for ii = 0 upto n_i - 1 : > s_i := subpath(ii,ii+1) of p_i ; > for jj = 0 upto n_j - 1 : > s_j := subpath(jj,jj+1) of p_j ; > found := s_i intersection_point s_j ; > if intersection_found : > index := index + 1 ; > drawdot found withpen pencircle scaled 4 > withtransparency (1,.5); > draw textext("\strut\ttbf " & decimal > index) ysized 3 shifted found withcolor white withtransparency (1,.5); > fi ; > endfor ; > endfor ; > endfor ; > endfor ; > > enddef ; > > \stopMPdefinitions > > \startMPpage > > picture first ; first := outlinetext.p("N") ; first := first > scaled 10 ; > picture second ; second := outlinetext.p("T") ; second := second > scaled 10 ; > > second := second rotatedaround(center second, 5) shifted (1,-1) ; > > filloutlinetext(first ) withcolor .5[blue,white] ; > filloutlinetext(second) withcolor .5[red,white] ; > > drawoutlinetext(first ) ; > drawoutlinetext(second) ; > > showoverlapinoutlines(first, second) ; > > \stopMPpage > > \startMPdefinitions > > def showoverlap(expr f, s) = > picture first ; first := outlinetext.p(f) ; first := first > scaled 10 ; > picture second ; second := outlinetext.p(s) ; second := second > scaled 10 ; > > filloutlinetext(first ) withcolor .5blue ; > drawoutlinetext(first ) ; > > filloutlinetext(second) withcolor .5red ; > drawoutlinetext(second) ; > > showoverlapinoutlines(first, second) ; > enddef ; > > \stopMPdefinitions > > \startMPpage > showoverlap("N","T") ; > \stopMPpage > > \startMPpage > showoverlap("\$","Q") ; > \stopMPpage > > \startMPpage > showoverlap("\tttf ABC","\tttf PQR") ; > \stopMPpage > > \stoptext Take a look, also, at the crossingunder macro in mp-tool.mpiv Alan ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / 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 ___________________________________________________________________________________
