绘制形状奇特的节点以包含 tikz 中的现有节点

Question 1

以下是一个建议，涉及完全重写您的代码。稍后可能会添加更多解释，但目前，一些关键点如下：

状态是用pic而不是新的节点集合来绘制的。
定位已调整，以便事物对称（似乎是要做的事情）
箭头画成两个\foreach环。

至于您的问题实际上涉及的部分，与此相关的代码如下，位于末尾tikzpicture：

\begin{scope}[on background layer]
\draw [line width=40pt,opacity=0.3,red,line cap=round,rounded corners] (IISScirc.center) -- (SIIScirc.center) -- (ISIScirc.center);
\draw [line width=40pt,opacity=0.3,blue,line cap=round,rounded corners] (SSIIcirc.center) -- (ISSIcirc.center) -- (SISIcirc.center);

\coordinate (A) at ($(ISSIcirc)!0.4!(SSIIcirc)$);
\coordinate (B) at ($(IISScirc)!0.6!(SIIScirc)$);
\draw [stealth-stealth,ultra thick,green]  ($(A)!20pt!90:(SSIIcirc)$) -- ($(B)!20pt!90:(IISScirc)$);
\end{scope}

前两行只是通过指定的三个点画了一条很宽的线。最后一行展示了计算这条宽线边缘点的一种方法。可能还有其他方法，而且可能更好，但我也不是一个巫师。

无论如何，首先发生的事情是两个coordinates 定义在两个节点之间的某个位置。在第一个 s 中，A位于ISSIcirc和之间 40% 的位置SSIIcirc。

语句中使用的坐标\draw计算在指定距离处投影到该点。所以意味着距离($(A)!20pt!90:(SSIIcirc)$)的点沿着与之间的线成 90 度角的线。为什么？因为粗线的线宽是，所以一半就可以到达它的边缘。20ptAASSIIcirc20pt40pt

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc, backgrounds, fit, arrows, arrows.meta}

\definecolor{colorS}{RGB}{0,154,128}
\definecolor{colorI}{RGB}{255,32,0}
\tikzset{
S/.style={circle,draw=black!50,fill=colorS!90,thick, minimum size=2mm, inner sep = 0mm},
I/.style={circle,draw=black!50,fill=colorI!90,thick, minimum size=2mm, inner sep = 0mm},
BigCirc/.style={circle,draw=black!50,thick,inner sep=0pt,minimum size=0pt, inner sep = 0mm},
pics/circles/.style args={#1#2#3#4}{
  code={
   \node [#1,minimum size=2mm] (#1#2#3#4top) at (0,0.25) {};
   \node [#2,minimum size=2mm] (#1#2#3#4left) at (-0.2165,-0.125) {};
   \node [#3,minimum size=2mm] (#1#2#3#4right) at (0.2165,-0.125) {};
   \node [#4,minimum size=2mm] (#1#2#3#4center) at (0,0) {};
   \draw (#1#2#3#4top) -- (#1#2#3#4center) -- (#1#2#3#4left) (#1#2#3#4center) -- (#1#2#3#4right);
    \node[BigCirc, fit = (#1#2#3#4left)(#1#2#3#4top)(#1#2#3#4right)] (circ) at (#1#2#3#4center) {};
   }
  }
}

\pgfmathsetmacro{\xA}{1.5}
\pgfmathsetmacro{\xB}{3}
\pgfmathsetmacro{\xC}{3.35}
\pgfmathsetmacro{\yA}{1.2}
\pgfmathsetmacro{\yB}{2.05}
\pgfmathsetmacro{\yC}{2.9}

\begin{document}


\begin{tikzpicture}
\pic (IIII) at (0,0)         {circles=IIII};
\pic (IIIS) at (\xA,\yB)     {circles=IIIS};
\pic (IISI) at (\xA,-\yB)    {circles=IISI};
\pic (ISII) at (\xB,\yA)     {circles=ISII};
\pic (SIII) at (\xB,-\yA)    {circles=SIII};
\pic (IISS) at (\xC,0)       {circles=IISS};
\pic (SIIS) at (5,\yA)       {circles=SIIS};
\pic (ISSI) at (5,-\yA)      {circles=ISSI};
\pic (ISIS) at (5,\yC)       {circles=ISIS};
\pic (SISI) at (5,-\yC)      {circles=SISI};
\pic (SSIS) at (10-\xA,\yB)  {circles=SSIS};
\pic (SSSI) at (10-\xA,-\yB) {circles=SSSI};
\pic (ISSS) at (10-\xB,\yA)  {circles=ISSS};
\pic (SISS) at (10-\xB,-\yA) {circles=SISS};
\pic (SSII) at (10-\xC,0)    {circles=SSII};
\pic (SSSS) at (10,0)        {circles=SSSS};

\foreach \A/\B in {
  IIIS/SIIS, IIIS/ISIS, IIIS/IISS, IISS/ISSS,
  IISS/SISS, ISIS/ISSS, ISIS/SSIS, SSIS/SSSS,
  ISSS/SSSS, SISS/SSSS, SSSI/SSSS, SIIS/SSIS}
    \draw [-{Latex[length=2.5mm,width=1mm,angle'=30]}] (\A circ) -- (\B circ);


\foreach \A/\B in {
  IIII/IIIS, IIII/ISII, IIII/SIII, IIII/IISI,
  IISI/IISS, IISI/ISSI, IISI/SISI,
  SSSI/SISI, SSSI/ISSI, SSSI/SSII,
  SIII/SIIS, SIII/SSII, ISSS/ISSI,
  ISII/ISIS, ISII/SSII, ISII/ISSI,
  SISI/SIII, SISI/SISS, SSIS/SSII}
    \draw [{Latex[length=2.5mm,width=1mm,angle'=30]}-{Latex[length=2.5mm,width=1mm,angle'=30]}] (\A circ) -- (\B circ);

\begin{scope}[on background layer]
\draw [line width=40pt,opacity=0.3,red,line cap=round,rounded corners] (IISScirc.center) -- (SIIScirc.center) -- (ISIScirc.center);
\draw [line width=40pt,opacity=0.3,blue,line cap=round,rounded corners] (SSIIcirc.center) -- (ISSIcirc.center) -- (SISIcirc.center);

\coordinate (A) at ($(ISSIcirc)!0.4!(SSIIcirc)$);
\coordinate (B) at ($(IISScirc)!0.6!(SIIScirc)$);
\draw [stealth-stealth,ultra thick,green]  ($(A)!20pt!90:(SSIIcirc)$) -- ($(B)!20pt!90:(IISScirc)$);
\end{scope}

\end{tikzpicture}
\end{document}

Answer