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如何使用 tikz l-systems 繪製不同顏色的不同線條

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如何使用 tikz l-systems 繪製不同顏色的不同線條

我正在嘗試製作一張無限根三元樹的圖片，下面的程式碼可以很好地完成這項工作。

\documentclass[12pt]{article}

\usepackage{tikz}
\usetikzlibrary{lindenmayersystems}
\begin{document}

\begin{figure}
    \begin{tikzpicture}
        \pgfdeclarelindenmayersystem{3-ary rooted tree}{
            \rule{L -> L [s+ [-L] [M] [+R]]}
            \rule{M -> M [s  [-L] [M] [+R]]}
            \rule{R -> R [s- [-L] [M] [+R]]}

            \symbol{L}{\pgflsystemdrawforward}
            \symbol{M}{\pgflsystemdrawforward}
            \symbol{R}{\pgflsystemdrawforward}
            \symbol{s}{\pgflsystemstep =0.4 \pgflsystemstep}
        }
        \draw[rotate = -90] l-system [l-system={3-ary rooted tree,axiom = [-L] [M] [+R], angle=45, step=6cm, order=5}];
    \end{tikzpicture}
\end{figure}
\end{document}

但是，我希望將每個字母對應的邊緣塗上不同的顏色，例如 L 紅色、M 綠色和 G 藍色。我試過

  \symbol{L}{\pgflsystemdrawforward}[red]
  \symbol{M}{\pgflsystemdrawforward}[green]
  \symbol{R}{\pgflsystemdrawforward}[blue]

但它似乎沒有做任何事情。有什麼建議麼？

答案1

經過一番思考，我認為最簡單的方法就是將R、M、L部分分別用不同的顏色繪製。所以我分成3-ary rooted tree一個R、一個M和一個L部分，每個部分只繪製三個「部分」之一，並使用\pgflsystemmoveforward而不是\pgflsystemdrawforward在其他兩個「部分」上。然後您可以使用 3 個不同的\draw指令和 3 種不同的顏色:)。 在此輸入影像描述

\documentclass[12pt]{article}

\usepackage{tikz}
\usetikzlibrary{lindenmayersystems}
\begin{document}

    \begin{figure}
        \begin{tikzpicture}
        \pgfdeclarelindenmayersystem{3-ary rooted tree-L}{  %define the left branch
            \rule{L -> L [s+ [-L] [M] [+R]]}
            \rule{M -> M [s  [-L] [M] [+R]]}
            \rule{R -> R [s- [-L] [M] [+R]]}

            \symbol{L}{\pgflsystemdrawforward}  % draw the L branch
            \symbol{M}{\pgflsystemmoveforward}  % only move
            \symbol{R}{\pgflsystemmoveforward}  % only move
            \symbol{s}{\pgflsystemstep =0.4 \pgflsystemstep}
        }
        \pgfdeclarelindenmayersystem{3-ary rooted tree-M}{ % define the middle branch
            \rule{L -> L [s+ [-L] [M] [+R]]}
            \rule{M -> M [s  [-L] [M] [+R]]}
            \rule{R -> R [s- [-L] [M] [+R]]}

            \symbol{L}{\pgflsystemmoveforward}  % only move
            \symbol{M}{\pgflsystemdrawforward}  % draw the M branch
            \symbol{R}{\pgflsystemmoveforward}  % only move
            \symbol{s}{\pgflsystemstep =0.4 \pgflsystemstep}
        }
        \pgfdeclarelindenmayersystem{3-ary rooted tree-R}{ % define the right branch
            \rule{L -> L [s+ [-L] [M] [+R]]}
            \rule{M -> M [s  [-L] [M] [+R]]}
            \rule{R -> R [s- [-L] [M] [+R]]}

            \symbol{L}{\pgflsystemmoveforward}  % only move
            \symbol{M}{\pgflsystemmoveforward}  % only move
            \symbol{R}{\pgflsystemdrawforward}  % draw the R branch
            \symbol{s}{\pgflsystemstep =0.4 \pgflsystemstep}
        }
        \draw[rotate = -90,color=blue] l-system [l-system={3-ary rooted tree-L,axiom = [-L] [M] [+R], angle=45, step=6cm, order=5}];
        \draw[rotate = -90,color=red] l-system [l-system={3-ary rooted tree-M,axiom = [-L] [M] [+R], angle=45, step=6cm, order=5}];
        \draw[rotate = -90,color=green] l-system [l-system={3-ary rooted tree-R,axiom = [-L] [M] [+R], angle=45, step=6cm, order=5}];

        \end{tikzpicture}
    \end{figure}
\end{document}

編輯：我發現了一個技巧（bug？功能？）只聲明樹一次：輸出與上面完全相同。技巧是您可以使用該\symbol命令僅在 3 個方向上移動而不進行繪製，並告訴它在三個方向之一上進行繪製，並且它將覆蓋該方向之前的“僅移動”命令。給它一個參數，你就可以讓它動態地繪製你想要的分支！

\documentclass[12pt]{article}

\usepackage{tikz}
\usetikzlibrary{lindenmayersystems}
\newcommand{\defbranch}[1]{
    \pgfdeclarelindenmayersystem{3-ary rooted tree#1}{  % dynamic definition of the branches
        \rule{L -> L [s+ [-L] [M] [+R]]}
        \rule{M -> M [s  [-L] [M] [+R]]}
        \rule{R -> R [s- [-L] [M] [+R]]}

        \symbol{L}{\pgflsystemmoveforward} % only move
        \symbol{M}{\pgflsystemmoveforward} % only move
        \symbol{R}{\pgflsystemmoveforward} % only move
        \symbol{#1}{\pgflsystemdrawforward}  % draw the branch (overrides previous command)
        \symbol{s}{\pgflsystemstep =0.4 \pgflsystemstep}
    }
}
\defbranch{L} % define the branches (needed only once per documents)
\defbranch{M}
\defbranch{R}

\newcommand{\branch}[2]{  %define command to draw branches.
    %You can add more parameters for step, angle, order,... if needed
    \draw[rotate = -90,color=#2] l-system [l-system={3-ary rooted tree#1,axiom = [-L] [M] [+R], angle=45, step=6cm, order=5}];
}

\begin{document}
\begin{figure}
    \begin{tikzpicture}
        \branch{L}{blue}
        \branch{M}{red}
        \branch{R}{green}
    \end{tikzpicture}
\end{figure}
\end{document}

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