@+(10,10) @+(0,20) @+(-10,10)' "b" \endxy \end{code $$\docode$$ "Hint": it uses a curve with three control points. \answercode \answertext{The author used \displaycode \end{exercise \DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Curving simply inserts |*\crvs| first in the stem such that |\crvs| is used instead of |\dir|. The only tricky bit is to put the control points on the stack. \DOCMODE( \xydef@\arr@curve#1{\curve@check \setcurvearrowinit@\arinit@@{#1}% \setcurvearrowexit@\arexit@ \DN@##1{\def\arstem@@{*\crvs##1}% \expandafter\next@\expandafter{\arstem@% \xyFN@\arr} {\xyuncatcodes \gdef\next#1#2{\def#1{\save @(,#2\restore \xylet@\setcurvearrowinit\=next {\xyuncatcodes \gdef\next#1{\def#1{\POS @i @) \xylet@\setcurvearrowexit\=next \xydef@\curve@check{% \xyerror{Formation @<vector> only available when curve extension loaded}{ \xywithoption{curve{\let\curve@check=\relax \DOCMODE) \TODO: The parsing is trivial and should be extended to include more exotic control point forms. \DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \note??=[object <modifier>s] A |@*{|\dots|}| formation defines what object <modifier>s should be used when building objects that are part of the arrow. This is mostly useful in conjunction with extensions that define additional |[|<shape>|]| modifiers, \eg, if a |[red]| <modifier> changes the colour of an object to red then |@*{[red]}| will make the entire arrow red. \DOCMODE( \xydef@\arr@modifiers#1{\def\armodifiers@@{#1}\xyFN@\arr} \DOCMODE) \DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \end{notescontd All the features of <path>s described above are available for arrows. \DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \subsection*{End \& log \DOCMODE( \xyendinput % $Log: xyarrow.doc,v $ % Revision 2.12 1994/10/25 11:34:25 kris % Interim release just before v3 [works with AMS-LaTeX 1.2]... % Revision 2.11 1994/07/05 10:37:32 kris % Third 3beta release [bug fixes]. % Experimental graph feature included (for ECCT-94 presentation). % Revision 2.10 1994/06/15 12:55:07 kris % Second 3beta release: bug fixes. % Revision 2.9 1994/06/09 14:59:19 kris % Release 3beta. % Revision 2.8 1994/04/08 04:30:00 kris % Second (bug fix) 3alpha release. % Revision 2.7 1994/03/08 10:25:18 kris % Release 3alpha. % Revision 2.6.9.1 1994/03/07 04:22:46 kris % Last internal 3alpha and pre-2.7 release. % NEW for version 2.7 based of path and arrow code in xypic.doc 2.6.1.1. \DOCMODE) \DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Tell Emacs how we are formatted: % Local Variables: % mode:latex % fill-prefix:"\t" % fill-column:77 % paragraph-separate:"^[ \t\f]*$\\|^[^\t]\\|\\\\\\\\\\|\\$\\$\\|[^\n\\\\][%&]" % paragraph-start:"^[ \t\f]*$\\|^[^\t]\\|\\\\\\\\\\|\\$\\$\\|[^\n\\\\][%&]" % End:

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