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TikZ：绘制的圆弧要么弯曲太多，要么不够长

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TikZ：绘制的圆弧要么弯曲太多，要么不够长 
\documentclass[convert = false, tikz]{standalone}
\usetikzlibrary{intersections}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
  \coordinate (O) at (0, 0);
  \coordinate (M) at (4, 0);

  \def\angle{130}

  \draw (O) -- (M);
  \draw (M) -- ++(\angle:2cm) coordinate (SOI);

  \begin{pgfinterruptboundingbox}
    \path[name path global = circ] (O) circle[radius = 1.5cm];
    \path[name path global = xline] (O) -- +(-10, 0);
    \path[name path global = yline] (O) -- +(0, 2);
    \path[name path global = toE] (SOI) -- ++(-170:8cm);
    \path[name intersections = {of = yline and toE, by = E}];
    \path[name intersections = {of = xline and toE, by = I}];
    \path[name intersections = {of = circ and toE, by = P1}];
  \end{pgfinterruptboundingbox}

  \draw (SOI) -- (E);

  \draw[-latex] let
    \p0 = (I),
    \p1 = (M),
    \p2 = (P1),
    \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
    \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
    \n3 = {1.5cm}
  in (I) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2];

  \draw[-latex] let
    \p0 = (O),
    \p1 = (M),
    \p2 = (P1),
    \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
    \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
    \n3 = {1.5cm}
  in (O) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2];

  \draw[-latex] let
    \p0 = (I),
    \p1 = (M),
    \p2 = (SOI),
    \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
    \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
    \n3 = {1.5cm}
  in (I) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2];

  \draw[-latex] let
    \p0 = (O),
    \p1 = (M),
    \p2 = (SOI),
    \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
    \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
    \n3 = {1.5cm}
  in (O) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2];
\end{tikzpicture}
\end{document}
  1. 使用(P1)

如果我们考虑上面的代码，足够长的弧线会弯曲太多，而具有适当弯曲量的弧线又太短。在这种情况下，如何才能获得具有正确长度的适当弯曲量？

  1. 使用(SOI)

两条曲线都太短，但似乎都没有超出弧度。

我可以在这里做什么？

在此处输入图片描述

@Jake，您的代码切换y并x旋转了我的矢量，使其看起来是水平的而不是垂直的。

 \draw[-latex] let
    \p0 = (O),
    \p1 = (M),
    \p2 = (SOI),
    \n1 = {atan2(\y1 - \y0, \x1 - \x0)},
    \n2 = {atan2(\y2 - \y0, \x2 - \x0)},
    \n3 = {veclen(\x2 - \x0, \y2 - \y1)},
    \n4 = {(\n1 + \n2) / 2}
  in (O) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2];

您发布的上述代码产生：

在此处输入图片描述

回到然后x产生y：

在此处输入图片描述

问题在于(I)坐标。它实际上从未存在，但LaTeX没有返回任何错误。路径toE从未与相交xline。因此，当我从绘制时(I)，构成交叉点原点的圆路径位于上方y = 0。因此，导致(I)圆弧很短。要纠正此问题，请设置

\path[name path global = toE] (SOI) -- ++(-170:9cm);

将射线的半径从9cm改为8cm。

答案1

问题在于(I)坐标。它实际上从未存在，但LaTeX没有返回任何错误。路径toE从未与相交xline。因此，当我从绘制时(I)，构成交叉点原点的圆路径位于上方y = 0。因此，导致(I)圆弧很短。要纠正此问题，请设置

\path[name path global = toE] (SOI) -- ++(-170:9cm);

将射线的半径从9cm改为8cm。

在当前设置下，从未存在交叉点。

在此处输入图片描述

不幸的是，LaTeX永远不会吐出错误，让线

\path[name intersections = {of = xline and toE, by = I}];

(I)在 的末尾创建点toE。由于我构建了路径，所以我实际上无法看到这一点，直到我决定仔细观察，并且没有错误消息说没有交点或类似的东西，我被引导相信一切正常。

通过新的变化，我们得到

在此处输入图片描述

通过设置

\path[name path global = circ] (I) circle[radius = 7cm];

并使用Jake的删除方法veclen并将其放入，pgfinterruptboundingbox否则您将会有不必要的空白。

  \draw[-latex] let
    \p0 = (I),
    \p1 = (M),
    \p2 = (P1),
    \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
    \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
    \n3 = {veclen(\x2 - \x0, \y2 - \y1)},
    \n4 = {(\n1 + \n2) / 2}
  in (I) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2]
  node[font = \tiny, fill = white, inner sep = 0] at ([shift = (I)] \n4:\n3)
  {\(\phi_1\)};

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