Contents of More bending arrows

More bending arrows

??=[arrows.bend] Finally, the |x|-form of arrows may bend around entries: just insert |`| d t, , a backquote, direction d, target t, for each `turn' that starts out in the d-direction and ends in a quarter turn towards the target t.

The possible directions are named like "hop"s:

$\displaystyle \xy$ *[o] $\displaystyle \cir$ < 1pc > = "c","c";(- 1, -1)**, p + /4pc/* + | dl|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(0, -1)**, p + /4pc/* + | d|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(1, -1)**, p + /4pc/* + | dr|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(1, 0)**, p + /4pc/* + | r|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(1, 1)**, p + /4pc/* + | ur|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(0, 1)**, p + /4pc/* + | u|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(- 1, 1)**, p + /4pc/* + | ul|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > ,"c";(- 1, 0)**, p + /4pc/* + | l|** $\displaystyle \dir$ -? > * $\displaystyle \dir$ > , $\displaystyle \xy$

and the possible targets include all those discussed above and in the reference manual [#!R94:XY-picRM!#].

Actually the direction letter is only required for the first in a series of turns since the final direction of one turn is the default for the following turn. The quarter turns will have radius 10pt by default, but this can be changed to any dimension R from a particular turn and onwards by inserting |/| R immediately after the |'| of the turn. Here is an example involving all of these features:
$\begin{code} \diagram \circ \xto \lq r[d] ^a \lq [rr] ^b \lq /4pt[rr] ^c \lq [rrr]^d \lq [... ... \circ & \circ & \circ \\ \circ & \circ & \circ & \circ \enddiagram \end{code}$
typesets

$\displaystyle \docode$

The example illustrates the following points:

If the segment can not be made as short as required then it will point `past' the target. This is useful for `going around' entries.
Each target appears as many times as there are quarter turns towards it, except the last target that appears both as the last |`|-target and once as an `ordinary' target to set the final stretch.
The sizes of the intermediate targets are ignored.

The bending arrows in section ??[basics.bends] are special cases of the above construction. There are several more advanced possibilities described in [#!R94:XY-picRM!#], notably the possibility for non-quarter turns.

The "v3" reference manual explains how the in- and out-going direction and orientation of each turn can be specified.