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This means that when such a body does not fit on the current page, it will be moved to the next -one. In the examples we will use figures, but everything we demonstrate here +one. In the examples we will use figures, but much of what we demonstrate here applies to all floats. A side float is a float which placement one way or another depends on the text @@ -1132,6 +1132,11 @@ The black rules are set up with: \setupbackgrounds [text] [leftmargin] [background=] \setupbackgrounds [text] [rightmargin] [background=] +At \CONTEXT\ and Bacho\TEX meetings it is now a tradition that Harald König and I +spend some time on figuring out what happens with border cases and interfences +with user intervention. As it's hard to nail down I decided to add some more +tracing and control. So, the remainder of this chapter is dedicated to Harald. + We will now demonstrate some features in a way that makes it possible to compare to the simple default case. Options can be passed as keywords: @@ -1188,7 +1193,7 @@ First we show some keyword variant, next some parameter driven versions. \placefigure[#1] {}{\externalfigure[dummy]} \samplefile{sapolsky} \samplefile{sapolsky} \endbuffer \framed - [background=color,backgroundcolor=white] + [background=color,backgroundcolor=white,offset=overlay] {\scale [width=.45\textwidth] {\typesetbuffer[foo]}}} @@ -1206,7 +1211,7 @@ First we show some keyword variant, next some parameter driven versions. \startplacefloat[#2] \externalfigure[dummy] \stopplacefloat \samplefile{sapolsky} \samplefile{sapolsky} \endbuffer \framed - [background=color,backgroundcolor=white] + [background=color,backgroundcolor=white,offset=overlay] {\scale [width=.45\textwidth] {\typesetbuffer[foo]}}} @@ -1362,11 +1367,117 @@ A second example that uses different settings is shown in \in {figure} \typebuffer[two] \startplacefigure[title={Side float tracing example 2, page 1.},reference=fig:side:two:1] - \scale[width=\textwidth]{\typesetbuffer[two][page=1]} + \framed + [background=color,backgroundcolor=white,offset=overlay] + {\scale[width=\textwidth]{\typesetbuffer[two][page=1]}} \stopplacefigure \startplacefigure[title={Side float tracing example 2, page 2.},reference=fig:side:two:2] - \scale[width=\textwidth]{\typesetbuffer[two][page=2]} + \framed + [background=color,backgroundcolor=white,offset=overlay] + {\scale[width=\textwidth]{\typesetbuffer[two][page=2]}} +\stopplacefigure + +\startbuffer[three] +\usemodule[simulate] + +\setuplayout + [tight] + +\setupbodyfont + [dejavu] + +\enabletrackers + [floats.anchoring] + +\setupfloats + [sidethreshold=.5\strutdp, % default, use "old" for previous implementation + step=small] + +\definemeasure[MyHeight][3cm] +\definemeasure[MyWidth] [3cm] + +% \setupheadertexts +% [width=\measure{MyWidth}\quad height=\measure{MyHeight}] + +\unexpanded\def\FakeWords#1% + {\simulatewords + [n=#1,m=#1,min=1,max=5,hyphen=no,color=text,line=yes,random=1234]} + +\starttext + +\startbuffer + \FakeWords{100}\par + \placefigure + [left] {oeps} + {\framed[width=\measure{MyWidth},height=\measure{MyHeight}]{}} + \FakeWords {2}\par + \FakeWords {3}\par + \FakeWords {5}\par + \FakeWords {4}\par + \FakeWords{200}\par + \placefigure + [left] {oeps} + {\framed[width=\measure{MyWidth},height=\measure{MyHeight}]{}} + \FakeWords{200}\par +\stopbuffer + +\dostepwiserecurse {\number\dimexpr3cm} {\number\dimexpr4cm} {\number\dimexpr0.25cm} { + \definemeasure[MyWidth][#1sp] + \dostepwiserecurse {\number\dimexpr3cm} {\number\dimexpr4cm} {\number\dimexpr0.25cm} { + \definemeasure[MyHeight][##1sp] + \start + \setupwhitespace[none] + \getbuffer \page + \stop + \start + \setupwhitespace[big] + \getbuffer \page + \stop + } +} +\stoptext +\stopbuffer + +Progressing next to a side float and determining how many lines to indent is a +somewhat complex mechamism because many factors play a role and spacing can +interfere badly. The decision about the number of lines to hang is to some extend +controllable but there are cases when you need to steer it (for instance by +scaling an image). In the next overviews we see the result of the following +somewhat complex setup: + +\typebuffer[three] + +The \type {step} parameter controls how we fill up the space when we need to +progress beyond it for instance because another float shows up or because we +issue a \type {\flushsidefloats}. Its value can be \type {big}, \type {medium} or +\type {small} and defaults to \type {small} which gives of enough precision. The +\type {sidethreshold} parameter controls the number of lines that we hang around +the float. Here we only show the consequence of the the threshold. A larger +threshold result in mode whitespace below the side float. You can zoom in to see +what happens at the bottom of the float (or run the examples yourself). + +\def\ShowSample#1% + {\framed + [background=color,backgroundcolor=white,offset=overlay] + {\scale + [width=\dimexpr(\textwidth-2\emwidth)/3\relax] + {\typesetbuffer[three][page=#1]}}} + +\startplacefigure[title={The working of default step and side threshold (no whitespace.},reference=fig:side:three:1] + \startcombination[3*3] + {\ShowSample {1}} {} {\ShowSample {3}} {} {\ShowSample {5}} {} + {\ShowSample {7}} {} {\ShowSample {9}} {} {\ShowSample {9}} {} + {\ShowSample{11}} {} {\ShowSample{13}} {} {\ShowSample{15}} {} + \stopcombination +\stopplacefigure + +\startplacefigure[title={The working of default step and side threshold (whitespace).},reference=fig:side:three:2] + \startcombination[3*3] + {\ShowSample {2}} {} {\ShowSample {4}} {} {\ShowSample {6}} {} + {\ShowSample {8}} {} {\ShowSample{10}} {} {\ShowSample{12}} {} + {\ShowSample{12}} {} {\ShowSample{14}} {} {\ShowSample{15}} {} + \stopcombination \stopplacefigure \stopchapter diff --git a/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03149.jpg b/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03149.jpg Binary files differnew file mode 100644 index 000000000..4de706984 --- /dev/null +++ b/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03149.jpg diff --git a/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03150.jpg b/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03150.jpg Binary files differnew file mode 100644 index 000000000..aa3849605 --- /dev/null +++ b/doc/context/sources/general/manuals/nodes/nodes-sun-pia-03150.jpg diff --git a/doc/context/sources/general/manuals/nodes/nodes.tex b/doc/context/sources/general/manuals/nodes/nodes.tex new file mode 100644 index 000000000..2e49c56d3 --- /dev/null +++ b/doc/context/sources/general/manuals/nodes/nodes.tex @@ -0,0 +1,1265 @@ +% interface=english modes=screen + +% author : Alan Braslau +% copyright : ConTeXt Development Team +% license : Creative Commons Attribution ShareAlike 4.0 International +% reference : pragma-ade.nl | contextgarden.net | texlive (related) distributions +% origin : the ConTeXt distribution +% +% comment : Because this manual is distributed with TeX distributions it comes with a rather +% liberal license. We try to adapt these documents to upgrades in the (sub)systems +% that they describe. Using parts of the content otherwise can therefore conflict +% with existing functionality and we cannot be held responsible for that. Many of +% the manuals contain characteristic graphics and personal notes or examples that +% make no sense when used out-of-context. +% +% comment : A prototype of the nodes module was presented at the ConTeXt 2016 user meeting +% and the first release was presented at the 2017 meeting. The module is part of +% the MetaFun code modules. +% +% comment : This manual orginates in an article by Alan so anything wrong in here is Hans +% fault as he converted it. +% +% comment : The conver images are form the NASA website. + +\definemeasure [layout:margin] [\paperheight/20] + +\setuplayout + [topspace=\measure{layout:margin}, + bottomspace=\measure{layout:margin}, + backspace=\measure{layout:margin}, + header=0pt, + footer=\measure{layout:margin}, + width=middle, + height=middle] + +\setupbodyfont + [dejavu,11pt] + +\setupwhitespace + [big] + +\setuphead + [chapter] + [style=\bfc, + interaction=all] + +\setuppagenumbering + [alternative=doublesided, + location=] + +\setupfootertexts + [\documentvariable{title}][\pagenumber] + [\pagenumber][\documentvariable{title}] + +\setuphead + [section] + [style=\bfb] + +\setuphead + [subsection] + [style=\bfa] + +\setuphead + [subsubsection] + [style=\bf, + after=] + +\setuplist + [interaction=all] + +\setupalign + [verytolerant,stretch] + +\setupnote + [footnote] + [next={ }, + split=verystrict, + scope=page] + +\setupinteraction + [state=start, + option=bookmark, + color=darkmagenta, + contrastcolor=darkmagenta] + +\setupinteractionscreen + [option=bookmark] + +\placebookmarks + [title,subject] + [title,subject] + +\enabledirectives + [references.bookmarks.preroll] + +\kindofpagetextareas\plusone % partial page. HH: low level, no high level switch (yet) + +\definetextbackground + [fiction] + [location=paragraph, + frame=off, + leftoffset=1ex, + rightoffset=1ex, + topoffset=1ex, + bottomoffset=1ex, + background=color, + backgroundcolor=lightgray] + +\defineparagraphs + [two] + [n=2, + offset=1ex, + background=color, + backgroundcolor=gray] + +\setupframed + [node] + [offset=1pt, + foregroundstyle=\tfa] + +\defineframed + [nodeGreen] + [node] + [foregroundcolor=darkgreen, + foregroundstyle=italic] + +\defineframed + [nodeSmall] + [node] + [foregroundstyle=\tfx] + +\startbuffer [bib] + @ARTICLE{Krebs1946, + author = {Krebs, H. A.}, + title = {Cyclic processes in living matter}, + journal = {Enzymologia}, + year = {1946}, + volume = {12}, + pages = {88--100} + } + + @ARTICLE{Bethe1939a, + author = {Bethe, H. A.}, + title = {Energy Production in Stars}, + journal = {Phys. Rev.}, + year = {1939}, + volume = {55}, + pages = {103–103}, + month = {Jan}, + doi = {10.1103/PhysRev.55.103}, + issue = {1}, + publisher = {American Physical Society}, + XXurl = {http://link.aps.org/doi/10.1103/PhysRev.55.103} + } + + @ARTICLE{Bethe1939b, + author = {Bethe, H. A.}, + title = {Energy Production in Stars}, + journal = {Phys. Rev.}, + year = {1939}, + volume = {55}, + pages = {434–456}, + month = {Mar}, + doi = {10.1103/PhysRev.55.434}, + issue = {5}, + publisher = {American Physical Society}, + XXurl = {http://link.aps.org/doi/10.1103/PhysRev.55.434} + } +\stopbuffer + +\usebtxdefinitions [apa] +\setupbtxrendering [apa] [pagestate=start] % index cite pages in bibliography + +\usebtxdataset [bib.buffer] + +\defineframed + [mynode] + [node] + [offset=1pt, + foregroundcolor=white] + +\startreusableMPgraphic{nodes::krebs} + + % The Bethe cycle for energy production in stars (1939), following + % Krebs (1946) + + save p ; path p[] ; + p1 := (for i=0 step 60 until 300: dir(90-i) .. endfor cycle) scaled 2.75cm ; + p0 := p1 scaled .5 ; + p2 := p1 scaled 1.5 ; + + draw node(p1,0,"\mynode{\chemical{^{12}C}}") ; + draw node(p1,1,"\mynode{\chemical{^{13}N}}") ; + draw node(p1,2,"\mynode{\chemical{^{13}C}}") ; + draw node(p1,3,"\mynode{\chemical{^{14}N}}") ; + draw node(p1,4,"\mynode{\chemical{^{15}O}}") ; + draw node(p1,5,"\mynode{\chemical{^{15}N}}") ; + + drawarrow fromtopaths.urt (true,p1,0,p1,1,"\mynode{a}") withcolor white ; + drawarrow fromtopaths.rt (true,p1,1,p1,2,"\mynode{b}") withcolor white ; + drawarrow fromtopaths.lrt (true,p1,2,p1,3,"\mynode{c}") withcolor white ; + drawarrow fromtopaths.llft(true,p1,3,p1,4,"\mynode{d}") withcolor white ; + drawarrow fromtopaths.lft (true,p1,4,p1,5,"\mynode{e}") withcolor white ; + drawarrow fromtopaths.ulft(true,p1,5,p1,6,"\mynode{f}") withcolor white ; + + draw node(p0,0,"\mynode{\chemical{^1H}}") ; + draw node(p0,2,"\mynode{\chemical{^1H}}") ; + draw node(p0,3,"\mynode{\chemical{^1H}}") ; + draw node(p0,5,"\mynode{\chemical{^1H}}") ; + + drawarrow fromtopaths(3/10,p0,0,p1,0.5) withcolor white ; + drawarrow fromtopaths(3/10,p0,2,p1,2.5) withcolor white ; + drawarrow fromtopaths(3/10,p0,3,p1,3.5) withcolor white ; + drawarrow fromtopaths(3/10,p0,5,p1,5.5) withcolor white ; + + draw node (p2,0,"\mynode{\chemical{^4He}}") ; + draw node (p2,1,"\mynode{$γ$}") ; + draw node.lrt (p2,2,"\mynode{$\mathrm{e}^+ + ν_\mathrm{e}$}") ; + draw node (p2,3,"\mynode{$γ$}") ; + draw node (p2,4,"\mynode{$γ$}") ; + draw node.ulft(p2,5,"\mynode{$\mathrm{e}^+ + ν_\mathrm{e}$}") ; + + drawarrow fromtopaths(-1/10,p1,0.5,p2,1) withcolor white ; + drawarrow fromtopaths(-1/10,p1,1.5,p2,2) withcolor white ; + drawarrow fromtopaths(-1/10,p1,2.5,p2,3) withcolor white ; + drawarrow fromtopaths(-1/10,p1,3.5,p2,4) withcolor white ; + drawarrow fromtopaths(-1/10,p1,4.5,p2,5) withcolor white ; + drawarrow fromtopaths(-1/10,p1,5.5,p2,0) withcolor white ; + +\stopreusableMPgraphic + +\startuseMPgraphic{CoverPage} + + StartPage ; + + % Alan wanted a sun in the background combined somehow with the energy + % harvesting molecule so here we go. The images that are used come from + % the NASA website and I used them as screen saver for a while. The + % version that I generate use another variant than the one on the users + % machine. + + draw textext("\externalfigure[\framedparameter{imagename}]") + xsized PaperWidth ysized (PaperHeight+4cm) + shifted center Page shifted (0,2cm); + + for i=1 upto 512 : + draw (textext("\reuseMPgraphic{nodes::krebs}") scaled (1/5 randomized 1/5)) + shifted (center Page randomized (PaperWidth,PaperHeight)) ; + endfor ; + + draw (textext.ulft("\word{\documentvariable{title}}") xsized (PaperWidth/2)) + shifted (lrcorner Page) + shifted (-PaperWidth/10,2PaperWidth/10) + withcolor white; + + draw (textext.ulft("\word{\documentvariable{author}}") xsized (PaperWidth/2)) + shifted (lrcorner Page) + shifted (-PaperWidth/10,PaperWidth/10) + withcolor white; + + StopPage ; + +\stopuseMPgraphic + +\startsetups document:start + + \doifmodeelse {atpragma} { + \startMPpage[imagename=nodes-sun-pia-03150] + \includeMPgraphic{CoverPage} + \stopMPpage + } { + \startMPpage[imagename=nodes-sun-pia-03149] + \includeMPgraphic{CoverPage} + \stopMPpage + } +\stopsetups + +\startdocument + [title=Nodes, + author=Alan Braslau, + copyright=\ConTeXt\ development team, + version=1.0] + +\startsubject [title=Introduction] + +The graphical representation of textual diagrams is an extremely useful tool in +the communication of idea. These are composed of graphical objects and blocks of +text or the combination of both, i.e. a decorated label or text block, in some +spatial relation to one another. \footnote {The spatial relation may be a +representation of a temporal relationship.} A simple example is shown \in {in +figure} [fig:AB]. + +\startplacefigure [reference=fig:AB] + \startMPcode + ahlength := 12pt ; + ahangle := 30 ; + ahvariant := 1 ; % dimpled + + u := 1cm ; + save nodepath ; path nodepath ; + nodepath := (left -- right) scaled u ; + + draw node(0,"\node{A}") ; + draw node(1,"\node{B}") ; + drawarrow fromto(0,0,1) ; + \stopMPcode +\stopplacefigure + +One often speaks of placing text with their accompanying decorations on \emph +{nodes}, points of intersection or branching or else points on a regular lattice. +The nodes of the above diagram are the two endpoints of a straight segment. + +\startbuffer +\startMPcode + save nodepath ; path nodepath ; + nodepath := (left -- right) scaled .75u ; + draw node(0,"A") ; + draw node(1,"B") ; + drawarrow fromto(0,0,1) ; +\stopMPcode +\stopbuffer + +The code producing \inlinebuffer\ \emph {could} be: + +\starttwo + \METAPOST + \startTEX + \startMPcode + draw node(0,"A") ; + draw node(1,"B") ; + drawarrow fromto(0,1) ; + \stopMPcode + \stopTEX +\two + \CONTEXT + \startTEX + \startnodes + \node[0]{A} + \node[1]{B} + \fromto [0,1] [option=arrow] + \stopnodes + \stopTEX +\stoptwo + +drawing an arrow from A to B (or from node 0 to node 1). + +\startitemize[packed] + \startitem + The \METAPOST\ code shown above has been simplified, as will be seen + later. + \stopitem + \startitem + The \CONTEXT\ module has yet to be coded (and may not be useful). + \stopitem +\stopitemize + +\stopsubject + +\startsubject [title=\METAPOST] + +\METAPOST\ is an inherently vectorial graphical language using \TEX\ to typeset +text; the \METAPOST\ language is integrated natively as MPlib in \CONTEXT. This +presents advantages over the use of an external graphical objects in providing a +great coherence of style along with great flexibility without bloat. \METAPOST\ +has further advantages over many other graphical subsystems, namely high +precision, high quality and the possibility to solve equations. This last point +is little used but should not be overlooked. + +It is quite natural in \METAPOST\ to locate these text nodes along a path or on +differing paths. This is a much more powerful concept than locating nodes at some +pair of coordinates, on a square or rectangular lattice, for example, as in a +table. These paths may be in three dimensions (or more); of course the printed +page will only be some projection onto two dimensions. Nor must the nodes be +located on the points defining a path: they may have as index any \emph {time} +along the path \type {p} ranging from the first defining point ($t = 0$) up to +the last point of a path ($t ≤ \mathtt{length(p)}$). \footnote {The time of a +cyclic path is taken modulo the length of the path.} + +For a given path \type {p}, nodes are defined (implicitly) as \type {picture} +elements: \typ {picture p.pic[] ;} This is a pseudo|-|array where the square +brackets indicates a set of numerical tokens, as in \type {p.pic[0]} but also +\type {p.pic0}. This number need not be an integer, and \type {p.pic[.5]} or +\type {p.pic.5} (not to be confused with \type {p.pic5}) are also valid. These +picture elements are taken to be located relative to the path \type {p}, with the +index \type {t} corresponding to a time along the path, as in \typ {draw p.pic[t] +shifted point t of p ;} (although one would not necessarily draw them in this +way). This convention allows the \quote {nodes} to be oriented and offset with +respect to the path in an arbitrary fashion. + +Note that a path can be defined and then nodes placed relative to this path, or +else the path may be simply declared yet remain undefined, to be determined +later, after the nodes are declared. Yet another possibility allows for the path +to be adjusted as needed, as a function of whatever nodes are to be occupied. +This will be illustrated through examples later. + +\stopsubject + +\startsubject [title=A few simple examples] + +\startplacefigure [location=left,reference=fig:square] + \startMPcode + path p ; p := fullsquare scaled 3cm ; + draw p ; + for i=0 upto length p: + draw point i of p + withcolor red + withpen pencircle scaled 5pt ; + endfor ; + % this looks better in the figure placement: + setbounds currentpicture to boundingbox currentpicture + rightenlarged 2mm ; + \stopMPcode +\stopplacefigure + +This might sound a bit arbitrary, so let's begin with the illustration of a +typical natural transformation of mathematics. A simple path and the points +defining this path are drawn in red here. Although it is trivial, this example +helps to introduce the \METAPOST\ syntax. (Of course, one should be able to use +this system without having to learn much \METAPOST.) + +\flushsidefloats + +\startTEX +\startMPcode + path p ; p := fullsquare scaled 3cm ; draw p ; + for i=0 upto length p: + draw point i of p + withcolor red + withpen pencircle scaled 5pt ; + endfor ; +\stopMPcode +\stopTEX + +\startbuffer +\startMPcode + save nodepath ; + path nodepath ; nodepath = p ; + draw node(0,"\node{$G(X)$}") ; + draw node(1,"\node{$G(Y)$}") ; + draw node(2,"\node{$F(Y)$}") ; + draw node(3,"\node{$F(X)$}") ; + drawarrow fromto.bot(0,0,1, "\nodeSmall{$G(f)$}") ; + drawarrow fromto.top(0,3,2, "\nodeSmall{$F(f)$}") ; + drawarrow fromto.rt (0,2,1, "\nodeSmall{$η_Y$}") ; + drawarrow fromto.lft(0,3,0, "\nodeSmall{$η_X$}") ; +\stopMPcode +\stopbuffer + +\startplacefigure [location=left,reference=fig:natural] + \getbuffer +\stopplacefigure + +Given the named path \type {nodepath}, we can define and draw nodes as well as +connections between them. + +\flushsidefloats + +\typebuffer [option=TEX] + +\startfiction +It is an important good practice with \METAPOST\ to reset or clear a variable +using the directive \type {save} as above for the suffix \type {nodepath}. The +macros used here rely on the creation of certain internal variables and may not +function correctly if the variable structure is not cleared. Indeed, any node may +contain a combination of picture elements, added successively, so it is very +important to \type {save} the variable, making its use local, rather than global. +This point is particularly true under \CONTEXT, where a single MPlib instance is +used and maintained over multiple runs. + +The \CONTEXT\ directives \type {\startMPcode} \unknown\ \type {\stopMPcode} +include grouping (\METAPOST\ \type {begingroup ;} \unknown\ \type {endgroup ;}) +and the use of \type {save} will make the suffix local to this code block. In the +examples above of \in{Figures} [fig:square] and \in [fig:natural], the path \type +{p} is not declared local (through the use of a \type {save}) therefore remains +available for other \METAPOST\ code blocks. We cannot do this with the default +suffix name \type {nodepath} without getting other unwanted consequences. +\stopfiction + +Note that one should not confuse the \METAPOST\ function \type {node()} with the +\CONTEXT\ command \type {\node{}}, defined as: + +\starttwo + \startTEX + \setupframed + [frame=off, + offset=1pt] + \stopTEX +\two + \startTEX + \defineframed + [nodeSmall] + [node] + [foregroundstyle=small] + \stopTEX +\stoptwo + +placing the text within a \CONTEXT\ frame (with the frame border turned|-|off). +The \METAPOST\ function \type {node(i,"...")} sets and returns a picture element +associated with a point on path \type {nodepath} indexed by its first argument. +The second argument here is a string that gets typeset by \TEX. + +The \METAPOST\ function \type {fromto()} returns a path segment going from two +points of the path \type {nodepath}, by default. The first argument (\type {0} in +the example above) can be used as a displacement to skew the path away from a +straight line. The last argument is a string to be typeset and placed midpoint of +the segment. The \emph {suffix} appended to the function name gives an offset +around this halfway point. This follows standard \METAPOST\ convention. + +\startfiction + The \CONTEXT\ syntax might be: + \startTEX + \startuseMPgraphic{node:square} + save nodepath ; path nodepath ; + nodepath := fullsquare scaled 6cm ; + \stopuseMPgraphic + + \setupfromto [option=arrow,position=auto] + + \startnodes [mp=node:square] + \node [0] {$G(X)$} + \node [1] {$G(Y)$} + \node [2] {$F(Y)$} + \node [3] {$F(X)$} + \fromto [0,1] [label={\tfxx $G(f)$}] + \fromto [3,2] [label={\tfxx $F(f)$}] + \fromto [2,1] [label={\tfxx $η_Y$}} + \fromto [3,0] [label={\tfxx $η_X$}] + \stopnodes + \stopTEX +\stopfiction + +Actually, as will be seen later, one can specify the use of any defined path, not +restricted to the built||in name \type {nodepath} that is used by default. +Furthermore, a function \type {fromtopaths()} can be used to draw segments +connecting any two paths which may be distinct. This, too, will be illustrated +later. + +\startbuffer +\startMPcode +save nodepath ; path nodepath ; +nodepath := fullsquare scaled 2cm ; +save A ; A = 3 ; draw node(A,"\node{A}") ; +save B ; B = 2 ; draw node(B,"\node{B}") ; +save C ; C = 0 ; draw node(C,"\node{C}") ; +save D ; D = 1 ; draw node(D,"\node{D}") ; + +drawarrow fromto(0,B,C) ; +drawarrow fromto(0,A,D) crossingunder fromto(0,B,C) ; +\stopMPcode +\stopbuffer + +\startplacefigure [location=left,reference=fig:crossingunder] + \getbuffer +\stopplacefigure + +Consider now the following code illustrating the \METAFUN\ operator \type +{crossingunder} that draws a path with segments cut|-|out surrounding the +intersection(s) with a second path segment. This operator is of such general use +that it has been added to the \METAFUN\ base. + +\flushsidefloats + +\typebuffer [option=TEX] + +\startplacefigure [reference=fig:sincos,location=left,title={\type{crossingunder}}] + \startMPcode + save u ; u := 2cm ; + save p ; path p[] ; + n := 64 ; + p2 := for i=0 upto n : if i>0 : .. fi (3u*(i/n), u*sind(720*(i/n))) endfor ; + p3 := for i=0 upto n : if i>0 : .. fi (3u*(i/n), u*cosd(720*(i/n))) endfor ; + p4 := point 0 of p2 -- point (length p2) of p2 shifted (left*.01u) ; + + draw p2 withcolor red ; + crossingscale := 20 ; + draw (p3 crossingunder p2) crossingunder p4 withcolor blue ; + crossingscale := 10 ; + drawarrow (p4 crossingunder p2) ; + \stopMPcode +\stopplacefigure + +Another illustration of the \type {crossingunder} operator in use is shown in \in +{figure} [fig:sincos]. Because the diagrams are all defined and drawn in +\METAPOST, one can easily extend the simple mode drawing with any sort of +graphical decoration using all the power of the \METAPOST\ language. + +This brings up a delicate point that has inhibited the development of a \CONTEXT\ +module up to now: \METAPOST\ is such a powerful language that it is difficult to +design a set of commands having equivalent flexibility. Perhaps, as is done +presently with the Chemistry package, one need only allow for the injection of +arbitrary \METAPOST\ code when needed for such special cases. + +Should it be done like this? + +\startfiction +\startTEX +\startnodes [mp=node:square] + \node [3] {A} + \node [2] {B} + \node [0] {C} + \node [1] {D} + \fromto [2,0] + \fromto [3,1] [option={under[2,0]}] % ? +\stopnodes +\stopTEX +\stopfiction + +Such a simple example illustrates why we favor a pure \METAPOST\ interface and +why a \CONTEXT\ interface will not be developed, at least for now. + +\stopsubject + +\startsubject [title=Cyclic diagrams] + +In a slightly more complicated example, that of a catalytic process given in the +\cite[authoryears] [Krebs1946] representation, where the input is indicated +coming into the cycle from the center of a circle and the products of the cycle +are spun|-|off from the outside of the circle, we start by defining a circular +path where each point corresponds to a step in the cyclic process. Our example +will use six steps. + +We will want to define a second circular path with the same number of points at +the interior of this first circle for the input and a third circular path at the +exterior for the output. Thus, + +\startTEX +\startMPcode + save p ; path p[] ; + % define a fullcircle path with nodes at 60° (rather than 45°) + p1 := (for i=0 step 60 until 300: dir(90-i) .. endfor cycle) scaled 2.75cm ; + p0 := p1 scaled .5 ; + p2 := p1 scaled 1.5 ; +\stopMPcode +\stopTEX + +\startplacefigure [location=left,title={The paths that we will use for anchoring for nodes.}] +\startMPcode + save p ; path p[] ; + p1 := (for i=0 step 60 until 300: dir(90-i) .. endfor cycle) scaled 2.75cm ; + p0 := p1 scaled .5 ; + p2 := p1 scaled 1.5 ; + for i=0 upto 2: + draw p[i] ; + for j=0 upto length p[i]: + draw point j of p[i] withpen currentpen scaled 5 withcolor red ; + endfor + label.bot("p" & decimal i, point 0 of p[i]) ; + endfor +\stopMPcode +\stopplacefigure + +Nodes will then be drawn on each of these three circles and arrows will be used +to connect these various nodes, either on the same path or else between paths. + +The \METAPOST\ function \type {fromto()} is used to give a segment pointing +between nodes. It \emph {assumes} the path \type {nodepath}, and in fact calls +the function \type {fromtopaths} that explicitly takes path names as arguments, +i.e. \type {fromto (d, i, j, ...)} is equivalent to \type {fromtopaths (d, +nodepath, i, nodepath, j, ...)}. + +As stated above, this segment can be a straight line or else a path that can be +bowed|-|away from this straight line by a transverse displacement given by the +function's first argument (given in units of the straight segment length). When +both nodes are located on a single, defined path, this segment can be made to lie +on or follow this path, such as one of the circular paths defined above. This +behavior is obtained by using any non|-|numeric value (such as \type {true}) in +place of the first argument. Of course, this cannot work if the two nodes are not +located on the same path. + +\startplacefigure [reference=fig:Bethe, + title={The \cite[author] [Bethe1939a] cycle for the energy production in stars + \cite[alternative=year,left=(,right=)] [Bethe1939a+Bethe1939b] in a + \cite[authoryears] [Krebs1946] representation of a catalytic process.}] +\startMPcode + + % The Bethe cycle for energy production in stars (1939), following Krebs (1946) + + save p ; path p[] ; + p1 := (for i=0 step 60 until 300: dir(90-i).. endfor cycle) scaled 2.75cm ; + p0 := p1 scaled .5 ; + p2 := p1 scaled 1.5 ; + + bboxmargin := 0pt ; + + draw node(p1,0,"\node{\chemical{^{12}C}}") ; + draw node(p1,1,"\node{\chemical{^{13}N}}") ; + draw node(p1,2,"\node{\chemical{^{13}C}}") ; + draw node(p1,3,"\node{\chemical{^{14}N}}") ; + draw node(p1,4,"\node{\chemical{^{15}O}}") ; + draw node(p1,5,"\node{\chemical{^{15}N}}") ; + + drawarrow fromtopaths.urt (true,p1,0,p1,1,"\nodeGreen{a}") ; + drawarrow fromtopaths.rt (true,p1,1,p1,2,"\nodeGreen{b}") ; + drawarrow fromtopaths.lrt (true,p1,2,p1,3,"\nodeGreen{c}") ; + drawarrow fromtopaths.llft(true,p1,3,p1,4,"\nodeGreen{d}") ; + drawarrow fromtopaths.lft (true,p1,4,p1,5,"\nodeGreen{e}") ; + drawarrow fromtopaths.ulft(true,p1,5,p1,6,"\nodeGreen{f}") ; + + draw node(p0,0,"\node{\chemical{^1H}}") ; + draw node(p0,2,"\node{\chemical{^1H}}") ; + draw node(p0,3,"\node{\chemical{^1H}}") ; + draw node(p0,5,"\node{\chemical{^1H}}") ; + + drawarrow fromtopaths(3/10,p0,0,p1,0.5) withcolor .6white ; + drawarrow fromtopaths(3/10,p0,2,p1,2.5) withcolor .6white ; + drawarrow fromtopaths(3/10,p0,3,p1,3.5) withcolor .6white ; + drawarrow fromtopaths(3/10,p0,5,p1,5.5) withcolor .6white ; + + draw node (p2,0,"\node{\chemical{^4He}}") ; + draw node (p2,1,"\node{$γ$}") ; + draw node.lrt (p2,2,"\node{$\mathrm{e}^+ + ν_\mathrm{e}$}") ; + draw node (p2,3,"\node{$γ$}") ; + draw node (p2,4,"\node{$γ$}") ; + draw node.ulft(p2,5,"\node{$\mathrm{e}^+ + ν_\mathrm{e}$}") ; + + drawarrow fromtopaths(-1/10,p1,0.5,p2,1) withcolor .6white ; + drawarrow fromtopaths(-1/10,p1,1.5,p2,2) withcolor .6white ; + drawarrow fromtopaths(-1/10,p1,2.5,p2,3) withcolor .6white ; + drawarrow fromtopaths(-1/10,p1,3.5,p2,4) withcolor .6white ; + drawarrow fromtopaths(-1/10,p1,4.5,p2,5) withcolor .6white ; + drawarrow fromtopaths(-1/10,p1,5.5,p2,0) withcolor .6white ; + +\stopMPcode +\stopplacefigure + +The circular arc segments labeled \emph {\darkgreen a–f} are drawn on \in +{figure} [fig:Bethe] using + +\startTEX +drawarrow fromtopaths.urt (true,p1,0,p1,1,"\nodeGreen{a}") ; +\stopTEX + +for example, where \type {\nodeGreen} is a frame that inherits from \type +{\node}, changing style and color: + +\startTEX +\defineframed + [nodeGreen] + [node] + [foregroundcolor=darkgreen, + foregroundstyle=italic] +\stopTEX +\stopfootnote + +The bowed|-|arrows feeding into the cyclic process and leading out to the +products, thus between different paths, from the path \type {p0} to the path +\type {p1} and from the path \type {p1} to the path \type {p2}, respectively, are +drawn using the deviations \type {+3/10} and \type {-1/10} (to and from +half|-|integer indices, thus mid|-|step, on path \type {p1}): + +\startTEX +drawarrow fromtopaths( 3/10,p0,0,p1,0.5) withcolor .6white ; +drawarrow fromtopaths(-1/10,p1,0.5,p2,1) withcolor .6white ; +\stopTEX + +\startsubsubject [title={A lesson in \METAPOST}] + +An \quote {array} of paths is declared through \typ {path p[] ;} it is not a +formal array, rather a syntactic definition of a collection of path variables +\type {p0}, \type {p1}, \unknown\ named beginning with the tag \quote {p} +followed by any number, not necessarily an integer (i.e. \type {p3.14} is a valid +path name). The syntax allows enclosing this \quote {index} within square +brackets, as in \type {p[0]} or, more typically, \type {p[i]}, where \type {i} +would be a numeric variable or the index of a loop. Note that the use of brackets +is required when using a negative index, as in \type {p[-1]} (for \type {p-1} is +interpreted as three tokens, representing a subtraction). Furthermore, the +variable \type {p} itself, would here be a numeric (by default), so \type {p[p]} +would be a valid syntactic construction! One could, additionally, declare a set +of variables \typ {path p[][] ;} and so forth, defining also \type {p[0][0]} +(equivalently, \type {p0 0}) for example as a valid path, coexisting with yet +different from the path \type {p0}. + +\METAPOST\ also admits variable names reminiscent of a structure: \typ {picture +p.pic[] ;} for example is used internally in the \type {node} macros, but this +becomes \typ {picture p[]pic[] ;} when using a path \quote {array} syntax. These +variable names are associated with the suffix \type {p} and become all undefined +by \typ {save p ;}. + +The \type {node} macros use the default name \type {nodepath} when no path is +explicitly specified. It is the user's responsibility to ensure the local or +global validity of this path if used. + +\stopsubsubject + +\stopsubject + +\startsubject [title=Tree diagrams] + +The tree diagram shown below is drawn using four paths, each one defining a row +or generation in the branching. The definition of the spacing of nodes was +crafted by hand and is somewhat arbitrary: 3.8, 1.7, and 1 for the first, second +and third generations. + +\startplacefigure [location=force,reference=fig:DNA] +\startMPcode + % third example: A tree diagram + + save u ; u := 2.25cm ; + save n ; n := 2 ; % n children per generation + + save p ; path p[] ; + p0 := origin ; + numeric d[] ; d1 := 3.8 ; d2 := 1.7 ; d3 := 1 ; + for g=1 upto 3: + p[g] := + for i=0 upto length(p[g-1]): + for c=0 upto n-1: + if (i+c)>0: -- fi + ((point i of p[g-1]) shifted (d[g]*(c/(n-1)-.5)*u,-u)) + endfor + endfor ; + endfor + + draw node(p0,0, "\node{DNA interactions with surfaces}") ; + draw node(p1,0, "\node{repulsive:}") ; + draw node(p1,1, "\node{attractive: adsorption}") ; + draw node(p2,0, "\node{confinement}") ; + draw node(p2,1, "\node[align=middle,location=high]{depletion,\\macromolecular\\crowding}") ; + draw node(p2,2, "\node{chemisorption}") ; + draw node(p2,3, "\node{physisorption}") ; + draw node(p3,5.5,"\node{immobilized}") ; + draw node(p3,7, "\node{mobile}") ; + + drawarrow fromtopaths(0,p0,0,p1,0) ; + drawarrow fromtopaths(0,p0,0,p1,1) ; + + drawarrow fromtopaths(0,p1,0,p2,0) ; + drawarrow fromtopaths(0,p1,0,p2,1) ; + drawarrow fromtopaths(0,p1,1,p2,2) ; + drawarrow fromtopaths(0,p1,1,p2,3) ; + + drawarrow fromtopaths(0,p2,2,p3,5.5) ; + drawarrow fromtopaths(0,p2,3,p3,5.5) ; + drawarrow fromtopaths(0,p2,3,p3,7) ; + +\stopMPcode +\stopplacefigure + +One can do better by allowing \METAPOST\ to solve equations and to determine this +spacing automatically. This will be illustrated by a very simple example where +nodes are first placed on a declared but undefined path. + +\startTEX +save p ; % path p ; +\stopTEX + +The \type {save p ;} assures that the path is undefined. This path will later get +defined based on the contents of the nodes and a desired relative placement. In +fact, it is not even necessary to declare that the suffix will be a path, as the +path will be declared and automatically built once the positions of all the nodes +are determined, which is why the \type {path} declaration is commented|-|out +above. + +The user is to be warned that solving equations in \METAPOST\ can be +non|-|trivial for those who are less mathematically inclined. One needs to +establish a coupled set of equations that is solvable: that is, fully but not +over|-|determined. + +A few helper functions have been defined: \type {makenode()} returns a suffix +(variable name) corresponding to the node's position. The first such node can be +placed at any finite point, for example the drawing's origin. The following nodes +can be placed in relation to this first node: + +% \startframed [frame=off,align=text,offset=overlay] % keep this together on one page. +\startTEX [style=small] +save nodepath ; +save first, second, third, fourth ; +pair first, second, third, fourth ; +first.i = 0 ; first = makenode(first.i, "\node{first}") ; +second.i = 1 ; second = makenode(second.i,"\node{second}") ; +third.i = 2 ; third = makenode(third.i, "\node{third}") ; +fourth.i = 3 ; fourth = makenode(fourth.i,"\node{fourth}") ; + +first = origin ; +second = first + + betweennodes.urt(nodepath,first.i, nodepath,second.i,whatever) ; +third = second + + betweennodes.lft(nodepath,second.i,nodepath,third.i, whatever) ; +fourth = third + + betweennodes.bot(nodepath,fourth.i,nodepath,first.i,3ahlength) ; +\stopTEX +% \stopframed + +The helper function \type {betweennodes()} returns a vector pointing in a certain +direction, here following the standard \METAPOST\ suffixes: \type {urt}, \type +{lft}, and \type {bot}, that takes into account the bounding boxes of the +contents of each node, plus an (optional) additional distance (here given in +units of the arrow||head length, \type {ahlength}). Using the keyword \type +{whatever} tells \METAPOST\ to adjust this distance as necessary. The above set +of equations is incomplete as written, so a fifth and final relation needs to be +added; the fourth node is also to be located directly to the left of the very +first node: \footnote {Equivalently, we could declare that the first node located +to the right of the fourth node: \typ {first = fourth + betweennodes.rt +(nodepath, first.i, nodepath, fourth.i, 3ahlength) ;}} + +\startTEX [style=small] +fourth = first + + betweennodes.lft(nodepath,fourth.i,nodepath,first.i,3ahlength) ; +\stopTEX + +Note that the helper function \type {makenode()} can be used as many times as +needed; if given no content, only returning the node's position. Additional nodes +can be added to this diagram along with appropriate relational equations, keeping +in mind that the equations must be solvable, of course. This last point is the +one challenge that most users might face. + +The function \type {node()} that was used previously and returning a picture +element to be drawn itself calls the function \type {makenode()}, used here. The +nodes have not been drawn as yet: + +\startTEX +for i = first.i, second.i, third.i, fourth.i : + draw node(i) ; + drawarrow fromto(0,i,i+1) ; +endfor +\stopTEX + +resulting in \in{figure} [fig:relative]. The path is now defined as one running +through the position of all of the defined nodes, and is cyclic. + +\startplacefigure [location=here,reference=fig:relative] +\startMPcode + save nodepath ; + save first, second, third, fourth ; + pair first, second, third, fourth ; + first.i = 0 ; first = makenode(first.i, "\node{first}") ; + second.i = 1 ; second = makenode(second.i,"\node{second}") ; + third.i = 2 ; third = makenode(third.i, "\node{third}") ; + fourth.i = 3 ; fourth = makenode(fourth.i,"\node{fourth}") ; + + first = origin ; + second = first + betweennodes.urt(nodepath,first.i, nodepath,second.i,whatever) ; + third = second + betweennodes.lft(nodepath,second.i,nodepath,third.i, whatever) ; + fourth = third + betweennodes.bot(nodepath,fourth.i,nodepath,first.i,3ahlength) ; + fourth = first + betweennodes.lft(nodepath,fourth.i,nodepath,first.i,3ahlength) ; + + for i = first.i, second.i, third.i, fourth.i : + draw node(i) ; + drawarrow fromto(0,i,i+1) ; + endfor +\stopMPcode +\stopplacefigure + +Using this approach, that of defining but not drawing the nodes until a complete +set of equations defining their relative positions has been constructed, imposes +several limitations: firstly, the nodes are expected to be numbered from $0$ up +to $n$, continuously, without any gaps for each defined path. This is just an +implicit convention of the path construction heuristic. Secondly, when finally +defining all the nodes and their positions, the path needs to be constructed. A +function, \type {makenodepath(p) ;} accomplishing this gets implicitly called +(once) upon the drawing of any \type {node()} or connecting \type {fromto}. Of +course, \type {makenodepath()} can always be explicitly called once the set of +equations determining the node positions is completely defined. + +\startparagraph [style=bold] +We again stress that the writing of a solvable yet not over|-|determined set of +equations can be a common source of error for many \METAPOST\ users. +\stopparagraph + +Another such example is the construction of a simple tree of descendance or +family tree. There are many ways to draw such a tree; in \in{figure} +[fig:descendance] we will show only three generations. + +\startplacefigure [location=here,reference=fig:descendance, + title={A tree of descendance}] +\startMPcode + save p ; % path p[], p[][] ; get automagically defined + save spacing ; spacing = 5pt ; + save d ; d = 4ahlength ; + + save mother, father ; pair mother, father ; + + mother = makenode(p,0,"\node{mother}") ; + father = makenode(p,1,"\node{father}") ; + + mother = origin ; + father = mother + betweennodes.rt(p,0,p,1,spacing) ; + + % first generation + save child, spouse ; pair child[], spouse[] ; + child = 0 ; spouse = 1 ; + + child1 = makenode(p0,child, "\node{child1}") ; + spouse1 = makenode(p0,spouse,"\node{spouse}") ; + child2 = makenode(p1,child, "\node{child2}") ; + spouse2 = makenode(p1,spouse,"\node{spouse}") ; + + .5[child1,child2] = mother + d*down ; + spouse1 = child1 + betweennodes.rt(p0,child, p0,spouse,spacing) ; + child2 = spouse1 + betweennodes.rt(p0,spouse,p1,child, whatever) ; + spouse2 = child2 + betweennodes.rt(p1,child, p1,spouse,spacing) ; + + % second generation + save grandchild, grandspouse ; pair grandchild[], grandspouse[] ; + grandchild1 = makenode(p0 0,child, "\node{grandchild1}") ; + grandspouse1 = makenode(p0 0,spouse,"\node{spouse}") ; + grandchild2 = makenode(p0 1,child, "\node{grandchild2}") ; + grandspouse2 = makenode(p0 1,spouse,"\node{spouse}") ; + grandchild3 = makenode(p1 0,child, "\node{grandchild3}") ; + grandspouse3 = makenode(p1 0,spouse,"\node{spouse}") ; + grandchild4 = makenode(p1 1,child, "\node{grandchild4}") ; + grandspouse4 = makenode(p1 1,spouse,"\node{spouse}") ; + + .5[grandchild1,grandchild2] = child1 + d*down ; + .5[grandchild3,grandchild4] = child2 + d*down ; + grandchild2 = grandchild1 + betweennodes.rt(p0 0,child,p0 1,child,spacing) ; + grandchild3 = grandchild2 + betweennodes.rt(p0 1,child,p1 0,child,spacing) ; + grandchild4 = grandchild3 + betweennodes.rt(p1 0,child,p1 1,child,spacing) ; + grandspouse1 = grandchild1 + nodeboundingpoint.bot(p0 0,child) + + nodeboundingpoint.lrt(p0 0,spouse) ; + grandspouse2 = grandchild2 + nodeboundingpoint.bot(p0 1,child) + + nodeboundingpoint.lrt(p0 1,spouse) ; + grandspouse3 = grandchild3 + nodeboundingpoint.bot(p1 0,child) + + nodeboundingpoint.lrt(p1 0,spouse) ; + grandspouse4 = grandchild4 + nodeboundingpoint.bot(p1 1,child) + + nodeboundingpoint.lrt(p1 1,spouse) ; + + draw node(p,0) ; + draw node(p,1) withcolor blue ; + + for i=0,1 : + draw node(p[i],child) ; + drawarrow fromtopaths(0,p,0,p[i],child) ; + draw node(p[i],spouse) withcolor blue ; + for j=0,1 : + draw node(p[i][j],child) ; + draw node(p[i][j],spouse) withcolor blue ; + endfor + drawarrow fromtopaths(0,p[i],child,p[i][0],child) ; + drawarrow fromtopaths(0,p[i],child,p[i][1],child) ; + endfor +\stopMPcode +\stopplacefigure + +We leave it as an exercise to the reader to come|-|up with the equations used to +determine this tree (one can look at source of this document, if necessary). + +The set of equations could be hidden from the user wishing to construct simple, +pre|-|defined types of diagrams. However, such cases would imply a loss of +generality and flexibility. Nevertheless, the \emph {node} module will probably +be extended in the future to provide a few simple models. One might be a +branching tree structure, yet even the above example as drawn does not fit into a +simple, general model. + +A user on the mailing list asked if it is possible to make structure trees for +English sentences with categorical grammar, an example of which is shown in \in +{Figure} [fig:grammar]. + +\startbuffer +\startMPcode + save p ; path p[] ; % we work first with unit paths. + save n ; n = 0 ; + forsuffixes $=People,from,the,country,can,become,quite,lonely : + p [n] = makenode(p[n],0,"\node{\it" & (str $) & "}") = (n,0) ; + n := n + 1 ; + endfor + save u ; u := TextWidth/n ; + + % build upward tree + + vardef makeparentnode(text t) = + save i, xsum, xaverage, ymax ; + i = xsum = 0 ; + forsuffixes $ = t : + clearxy ; z = point infinity of $ ; + xsum := xsum + x ; + if unknown ymax : ymax = y ; elseif y > ymax : ymax := y ; fi + i := i + 1 ; + endfor + xaverage = xsum / i ; + ymax := ymax + 1 ; + forsuffixes $ = t : + clearxy ; + z = point infinity of $ ; + $ := $ & z -- (x,ymax) if i>1 : -- (xaverage,ymax) fi ; + endfor + enddef ; + + makeparentnode(p2,p3) ; + makeparentnode(p4,p5) ; + makeparentnode(p6,p7) ; + makeparentnode(p1,p2) ; + makeparentnode(p0,p1) ; + makeparentnode(p4,p6) ; + makeparentnode(p0,p4) ; + makeparentnode(p0) ; + + % the paths are all defined but need to be scaled. + + for i=0 upto n-1 : + p[i] := p[i] xyscaled (u,.8u) ; + draw node(p[i],0) ; + endfor + + save followpath ; boolean followpath ; followpath = true ; + + draw fromtopaths(followpath,p0,0,p0,1,"\node{H:N}") ; + draw fromtopaths(followpath,p1,0,p1,1,"\node{Rel:Prep}") ; + draw fromtopaths(followpath,p2,0,p2,1,"\node{Dr:Dv}") ; + draw fromtopaths(followpath,p3,0,p3,1,"\node{H:N}") ; + draw fromtopaths(followpath,p4,0,p4,1,"\node{M:Aux}") ; + draw fromtopaths(followpath,p5,0,p5,1,"\node{H:Mv}") ; + draw fromtopaths(followpath,p6,0,p6,1,"\node{M:Adv}") ; + draw fromtopaths(followpath,p7,0,p7,1,"\node{H:Adj}") ; + + draw fromtopaths(followpath,p1,1,p1,2) ; + draw fromtopaths(followpath,p2,3,p2,4) ; + draw fromtopaths(followpath,p1,2,p1,3,"\node{M:PP}") ; + draw fromtopaths(followpath,p2,1,p2,2) ; + draw fromtopaths(followpath,p3,1,p3,2) ; + draw fromtopaths(followpath,p2,2,p2,3,"\node{Ax:NP}") ; + draw fromtopaths(followpath,p4,1,p4,2) ; + draw fromtopaths(followpath,p5,1,p5,2) ; + draw fromtopaths(followpath,p4,2,p4,3,"\node{P:VP}") ; + draw fromtopaths(followpath,p6,1,p6,2) ; + draw fromtopaths(followpath,p7,1,p7,2) ; + draw fromtopaths(followpath,p6,2,p6,3,"\node{PCs:AdjP}") ; + draw fromtopaths(followpath,p0,1,p0,2) ; + draw fromtopaths(followpath,p1,3,p1,4) ; + draw fromtopaths(followpath,p0,2,p0,3,"\node{S:NP}") ; + draw fromtopaths(followpath,p4,3,p4,4) ; + draw fromtopaths(followpath,p6,3,p6,4) ; + draw fromtopaths(followpath,p4,4,p4,5,"\node{Pred:PredP}") ; + draw node(p0,4.5,"\node{Cl}") ; + draw fromtopaths(followpath,p0,3,p0,4.5) ; + draw fromtopaths(followpath,p4,5,p4,6) ; +\stopMPcode +\stopbuffer + +\startplacefigure [reference=fig:grammar, + title=A categorical grammer structure tree] + \getbuffer +\stopplacefigure + +I chose to define a series of parallel paths, one per word, with one path +terminating whenever it joins another path (or paths) at a common parent. +Labeling each branch of the tree structure requires, of course, a knowledge of +the tree structure. + +\typebuffer [option=TEX] + +\stopsubject + +\startsubject [title=Two final examples] + +\defineframed + [smallnode] + [node] + [foregroundstyle=\tfxx, + background=color, + backgroundcolor=white] + +\startbuffer[mp:tikz-cd] +\startMPcode + save nodepath ; save l ; l = 5ahlength ; + save X, Y, Z, XxY, T ; + pair X, Y, Z, XxY, T ; + XxY.i = 0 ; XxY = makenode(XxY.i,"\node{$X\times_Z Y$}") ; + X.i = 1 ; X = makenode(X.i, "\node{$X$}") ; + Z.i = 2 ; Z = makenode(Z.i, "\node{$Z$}") ; + Y.i = 3 ; Y = makenode(Y.i, "\node{$Y$}") ; + T.i = 4 ; T = makenode(T.i, "\node{$T$}") ; + XxY = origin ; + X = XxY + betweennodes.rt (nodepath,XxY.i,nodepath,X.i) + (l,0) ; + Z = X + betweennodes.bot(nodepath,X.i, nodepath,Z.i) + (0,-.8l); + Y = XxY + betweennodes.bot(nodepath,XxY.i,nodepath,Y.i) + (0,-.8l) ; + T = XxY + nodeboundingpoint.ulft(XxY.i) + + nodeboundingpoint.lft (T.i) + l*dir(135) ; + for i = XxY.i, X.i, Z.i, Y.i, T.i: + draw node(i) ; + endfor + drawarrow fromto.top(0, XxY.i,X.i,"\smallnode{$p$}") ; + drawarrow fromto.rt (0, X.i,Z.i,"\smallnode{$f$}") ; + drawarrow fromto.top(0, Y.i,Z.i,"\smallnode{$g$}") ; + drawarrow fromto.rt (0, XxY.i,Y.i,"\smallnode{$q$}") ; + drawarrow fromto.top( .13,T.i,X.i,"\smallnode{$x$}") ; + drawarrow fromto.urt(-.13,T.i,Y.i,"\smallnode{$y$}") ; + drawarrow fromto (0, T.i,XxY.i,"\smallnode{$(x,y)$}") + dashed withdots scaled .5 + withpen currentpen scaled 2 ; +\stopMPcode +\stopbuffer + +\startplacefigure [location=left,reference=fig:tikz-cd] + \getbuffer[mp:tikz-cd] +\stopplacefigure + +The following example, shown in \in{figure} [fig:tikz-cd] and drawn here using +the present \METAPOST\ \type {node} macros, is inspired from the TikZ CD +(commutative diagrams) package. \footnote {The TikZ-CD package uses a totally +different approach: the diagram is defined and laid|-|out as a table with +decorations (arrows) running between cells.} The nodes are again given relative +positions rather than being placed on a predefined path. The arrow labeled \quote +{$(x,y)$} is drawn \typ {dashed withdots} and illustrates how the line gets +broken, here \type {crossingunder} its centered label. + +\startparagraph [style=small] + \typebuffer[mp:tikz-cd] [option=TEX] +\stopparagraph + +% \doifmode {screen} {\page [yes]} + +\in {Figure} [fig:tikz-cd2] is another \quotation{real|-|life} example, also +inspired by TikZ-CD. + +\startbuffer[mp:tikz-cd2] +\startMPcode + save nodepath ; save l ; l = 5ahlength ; + save A, B, C, D, E ; + pair A, B, C, D, E ; + A.i = 0 ; A = makenode(A.i,"\node{$\pi_1(U_1\cap U_2)$}") ; + B.i = 1 ; B = makenode(B.i,"\node{$\pi_1(U_1)\ast_{\pi_1(U_1\cap U_2)}\pi_1(U_2)$}") ; + C.i = 2 ; C = makenode(C.i,"\node{$\pi_1(X)$}") ; + D.i = 3 ; D = makenode(D.i,"\node{$\pi_1(U_2)$}") ; + E.i = 4 ; E = makenode(E.i,"\node{$\pi_1(U_1)$}") ; + A = origin ; + B = A + betweennodes.rt(nodepath,A.i,nodepath,B.i) + ( l,0) ; + C = B + betweennodes.rt(nodepath,B.i,nodepath,C.i) + (.7l,0) ; + D = .5[A,B] + (0,-.9l) ; + E = .5[A,B] + (0, .9l) ; + + for i = A.i, B.i, C.i, D.i, E.i : + draw node(i) ; + endfor + drawarrow fromto.llft( 0,A.i,D.i,"\smallnode{$i_2$}") ; + drawarrow fromto.ulft( 0,A.i,E.i,"\smallnode{$i_1$}") ; + drawarrow fromto ( 0,D.i,B.i) ; + drawarrow fromto ( 0,E.i,B.i) ; + drawarrow fromto.urt( .1,E.i,C.i,"\smallnode{$j_1$}") ; + drawarrow fromto.lrt(-.1,D.i,C.i,"\smallnode{$j_2$}") ; + drawarrow fromto.top( 0,B.i,C.i) dashed evenly ; + draw textext.top("{\tfxx\strut$\simeq$}") + shifted point .4 of fromto(0,B.i,C.i) ; +\stopMPcode +\stopbuffer + +\startplacefigure [location=here,reference=fig:tikz-cd2] + \getbuffer[mp:tikz-cd2] +\stopplacefigure + +\startparagraph [style=small] + \typebuffer[mp:tikz-cd2] [option=TEX] +\stopparagraph + +\placefloats + +\stopsubject + +\startsubject [title=Conclusions] + +It was decided at the 2017 \CONTEXT\ Meeting in Maibach, Germany where this +package was presented that there was little use of developing a purely \CONTEXT\ +interface. Rather, the \METAPOST\ package should be sufficiently accessible. + +\stopsubject + +\startsubject [title=References] + + \placelistofpublications + +\stopsubject + +\stoptitle + +\stoptext |
