使 TEX TIKZ FIGURE 用箭头对称

Question

\begin{tikzpicture}[->,shorten >=1pt,auto,node distance=3cm,
  main node/.style={draw}]
  \node[main node] (1) {A};
  \node[main node] (2) [right of=1] {B};
  \node[main node] (3) [right of=2] {C};
  \node[main node] (4) [below left of=3,xshift=1cm] {D};

  \path[every node/.style={font=\sffamily\small}]


     (2) edge [bend right] node [left] {} (4)
     (3) edge [bend left] node [left] {} (4)



\end{tikzpicture}

看到进入 D 的箭头不对称了吗？我怎样才能使它们对称并从侧面进入？

Answer 1

节点n2和n4， 和n3之间的边只有在节点 位于节点和的水平中间n4时才是对称的。如果不是，那么某些对称性只能近似，例如节点 处的连接点是对称的：n4n2n3n4

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{calc,
                positioning}

\begin{document}
    \begin{tikzpicture}[
node distance=22mm and 22mm,
every edge/.style = {draw, ->, shorten >=1pt},
       box/.style = {draw, minimum size=8mm, font=\sffamily\small},
                        ]
\node (n1) [box]                {A};
\node (n2) [box, right=of n1]   {B};
\node (n3) [box, right=of n2]   {C};
\node (n4) [box, below=of $(n2.south)!0.5!(n3.south)$]   {D};
%
\path   (n2) edge [bend right]  (n4)
        (n3) edge [bend  left]  (n4);
    \end{tikzpicture}

    \begin{tikzpicture}[
node distance=22mm and 22mm,
every edge/.style = {draw, ->, shorten >=1pt},
       box/.style = {draw, minimum size=8mm, font=\sffamily\small},
                        ]
\node (n1) [box]                {A};
\node (n2) [box, right=of n1]   {B};
\node (n3) [box, right=of n2]   {C};
\node (n4) [box, below right=22mm and 8 mm of n2.east]  {D};
%
\path   (n2) edge [bend right]  (n4.west)
        (n3) edge [bend  left]  (n4.east);
    \end{tikzpicture}
\end{document}

第一个图像代码示例的结果：

第二个示例的结果：

在图像代码中，我将节点名称从 1、2、3 和 4 更改为 n1、n2、n3 和 n4。