Cómo dibujar diferentes líneas con diferentes colores usando tikz l-systems

Question

Estoy intentando hacer una imagen de un árbol ternario con raíces infinitas; el siguiente código hará el trabajo bastante bien.

\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}

Sin embargo, me gustaría que los bordes correspondientes a cada letra se colorearan con diferentes colores, digamos L rojo, M verde y G azul. Lo intenté

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

pero no parece hacer nada. ¿Alguna sugerencia?

Answer 1

Después de pensarlo un poco, creo que la forma más sencilla es dibujar las partes R,M,L por separado en diferentes colores. Así que me dividí 3-ary rooted treeen a R, a My a Lpart, cada uno dibujando solo una de las tres "partes" y usando \pgflsystemmoveforwarden lugar de \pgflsystemdrawforwardlas otras dos. Luego puedes usar 3 \drawcomandos diferentes con 3 colores diferentes :).

\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}

---

Editar: Encontré un truco (¿error? ¿característica?) para declarar el árbol solo una vez: el resultado es exactamente el mismo que el anterior. El truco es que puedes usar el \symbolcomando para moverte en las 3 direcciones sin dibujar, y decirle que dibuje en una de las tres, y anulará el comando anterior "solo mover" para esa dirección. ¡Dale un parámetro y ya tendrás que dibujar dinámicamente la rama que quieras!

\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}