我想将 π 符号置于 π 数字螺旋的中心。我想知道是否可以更改 π 符号下数字的颜色？目前，数字是可见的，但我希望字体也能改变颜色。
\documentclass[tikz,border=5]{standalone}
\usetikzlibrary{decorations.text}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[
decoration={
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text effects along path,
text={%
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},
text effects/.cd,
text along path,
character count=\i, character total=\n,
characters={scale=1-\i/\n}
}
]
\draw [decorate] (0,0)
\foreach \i [evaluate={\r=(\i/1800)^2;}] in {0,5,...,4000}{ -- (\i:\r)};
\filldraw[blue,opacity=0.7] (-3.32,1.88) .. controls (-2.62,4.28) and (0.04,2.87) .. (1.48,3.41) .. controls (1.38,2.54) and (0.57,2.53) .. (0.09,2.48) .. controls (0.08,1.03) and (-0.48,-1.4) .. (0.82,-0.31) .. controls (0.78,-1.24) and (-1.71,-2.57) .. (-0.31,2.51) .. controls (-0.87,2.5) and (-0.87,2.5) .. (-1.48,2.53) .. controls (-1.49,1.31) and (-2.05,-1.77) .. (-2.93,-1.1) .. controls (-3.48,-0.36) and (-2.27,-0.74) .. (-1.88,2.55) .. controls (-2.47,2.51) and (-2.79,2.36) .. (-3.32,1.88);
\end{tikzpicture}
\end{document}
如果有人知道创建圆周率数字的方法，而不是将它们复制粘贴到代码中，那就太好了，但我认为这只是一些 Python 代码的问题，所以我可能能够解决它。谢谢
答案1
只是做
\filldraw[blue, opacity=0.7] (-3.32,1.88) .. controls (-2.62,4.28) and (0.04,2.87) .. (1.48,3.41) .. controls (1.38,2.54) and (0.57,2.53) .. (0.09,2.48) .. controls (0.08,1.03) and (-0.48,-1.4) .. (0.82,-0.31) .. controls (0.78,-1.24) and (-1.71,-2.57) .. (-0.31,2.51) .. controls (-0.87,2.5) and (-0.87,2.5) .. (-1.48,2.53) .. controls (-1.49,1.31) and (-2.05,-1.77) .. (-2.93,-1.1) .. controls (-3.48,-0.36) and (-2.27,-0.74) .. (-1.88,2.55) .. controls (-2.47,2.51) and (-2.79,2.36) .. (-3.32,1.88);
\path (current bounding box.center);
\pgfgetlastxy\xxx\yyy
\typeout{\xxx, \yyy}
给我们
-28.45274pt, 24.32698pt
在日志文件中，这意味着圆周率符号的中心位于该坐标。只需将圆周率路径向相反方向移动，我们就会得到一条以 (0, 0) 为中心的路径。如果您不喜欢这样，则需要进行更多微调。
对于角色，我只是使用类似的风格手册中的例子：
characters={
scale=1-\i/\n,
text depth=+0pt,
text height=+.7em,
/utils/exec=\pgfmathparse{\i/\n*100},
text=red!\pgfmathresult!green
}
这将给你
我注释掉了一半以上的数字，因为路径不够长。剩余的字符不会添加到螺旋中，而且看起来不太好，因为缩放因子没有达到 0。
代码
\documentclass[tikz, border=5pt, convert]{standalone}
\usetikzlibrary{decorations.text}
\begin{document}
\begin{tikzpicture}[
decoration={
reverse path,
text effects along path,
text={%
3{,}%
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},
text effects/.cd,
text along path,
character count=\i, character total=\n,
characters={
scale/.expanded=1-\i/\n,
text depth=+0pt,
text height=+.7em,
/utils/exec=\pgfmathparse{\i/\n*100},
text=red!\pgfmathresult!green
}
}
]
\draw [decorate] (0,0)
\foreach \i [evaluate={\r=(\i/1800)^2;}] in {0,5,...,4000}{ -- (\i:\r)};
\filldraw[shift={(28.45274pt, -24.32698pt)}, blue, opacity=0.7]
(-3.32,1.88) .. controls (-2.62,4.28) and (0.04,2.87) .. (1.48,3.41)
.. controls (1.38,2.54) and (0.57,2.53) .. (0.09,2.48)
.. controls (0.08,1.03) and (-0.48,-1.4) .. (0.82,-0.31)
.. controls (0.78,-1.24) and (-1.71,-2.57) .. (-0.31,2.51)
.. controls (-0.87,2.5) and (-0.87,2.5) .. (-1.48,2.53)
.. controls (-1.49,1.31) and (-2.05,-1.77) .. (-2.93,-1.1)
.. controls (-3.48,-0.36) and (-2.27,-0.74).. (-1.88,2.55)
.. controls (-2.47,2.51) and (-2.79,2.36) .. (-3.32,1.88);
%\path (current bounding box.center);
%\pgfgetlastxy\xxx\yyy
%\typeout{\xxx, \yyy}
\end{tikzpicture}
\end{document}
答案2
从@Qrrbrbirlbel 的代码开始，我使用 来local bounding box避免手动移动。bezier bounding box来自bbox提供更好的边界框。 - 只是偶然它们的中心接近。
\documentclass[tikz, border=1cm]{standalone}
\usetikzlibrary{decorations.text, bbox}
\begin{document}
\begin{tikzpicture}[
decoration={
reverse path,
text effects along path,
text={%
3{,}%
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},
text effects/.cd,
text along path,
character count=\i, character total=\n,
characters={
scale/.expanded=1-\i/\n,
text depth=+0pt,
text height=+.7em,
/utils/exec=\pgfmathparse{\i/\n*100},
text=red!\pgfmathresult!green
}}]
\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background, main, foreground}
\begin{scope}[local bounding box=pi, bezier bounding box]
\shade[top color=blue, bottom color=red, opacity=0.7, scale=1.4]
(-3.32,1.88) .. controls (-2.62,4.28) and (0.04,2.87) .. (1.48,3.41)
.. controls (1.38,2.54) and (0.57,2.53) .. (0.09,2.48)
.. controls (0.08,1.03) and (-0.48,-1.4) .. (0.82,-0.31)
.. controls (0.78,-1.24) and (-1.71,-2.57) .. (-0.31,2.51)
.. controls (-0.87,2.5) and (-0.87,2.5) .. (-1.48,2.53)
.. controls (-1.49,1.31) and (-2.05,-1.77) .. (-2.93,-1.1)
.. controls (-3.48,-0.36) and (-2.27,-0.74).. (-1.88,2.55)
.. controls (-2.47,2.51) and (-2.79,2.36) .. (-3.32,1.88);
\end{scope}
\begin{pgfonlayer}{background}
\draw[decorate, shift=(pi.center)] (0,0) \foreach \i [evaluate={\r=(\i/1800)^2;}] in {0,5,...,4000}{ -- (\i:\r)};
\end{pgfonlayer}
\end{tikzpicture}
\end{document}
