> For the complete documentation index, see [llms.txt](https://ayakaleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ayakaleaf-pro.ayaka.space/latex/zh-cn/tu-xing-he-biao-ge/04-picture-environment.md).
# 直接在 LaTeX 中绘制图表
## 引言
LaTeX 内置的 `picture` 环境可用于创建图表/图形——你不需要 *需要* 加载任何外部宏包即可使用它，但像以下宏包这样的包： [`pict2e`](https://ctan.org/pkg/pict2e?lang=en) 和 [`picture`](https://ctan.org/pkg/picture) 是为了增强或改进其功能而编写的。
本文对 `picture` 环境作简要介绍，所有示例都使用 [`pict2e` 宏包](https://ctan.org/pkg/pict2e?lang=en)。更详尽的文档和一系列有用的示例可在以下资源中轻松找到：
* [LaTeX2e 非官方参考手册](https://latexref.xyz/picture.html)
* [《LaTeX2ε 不太短的介绍》](https://tobi.oetiker.ch/lshort/lshort.pdf) （见第 5 章）
* [Wikibooks](https://en.wikibooks.org/wiki/LaTeX/Picture)
* [带有标签的提问 `picture-mode` 在 tex.stackexchange 上](https://tex.stackexchange.com/questions/tagged/picture-mode)
* [`pict2e` 包文档](https://mirror.ox.ac.uk/sites/ctan.org/macros/latex/contrib/pict2e/pict2e.pdf)
与功能强大且复杂的图形工具如 [TikZ/PGF](https://en.wikipedia.org/wiki/PGF/TikZ), [MetaPost](https://tug.org/metapost.html), [PSTricks](https://ctan.org/topic/pstricks?lang=en) 或 [Asymptote](https://ctan.org/pkg/asymptote?lang=en) 该 `picture` 环境看起来可能相当有限，但有时它足以满足你的需求。
## 创建新的 picture
创建新的 picture 通常包括以下步骤：
1. 定义你希望使用的绘图单位大小；
2. 声明一个 `picture` 定义图形尺寸的环境；
3. 使用以下命令绘制各个图形组件： `\put`, `\multiput` 或 `\qbezier` 命令。
### 定义绘图单位的大小
要创建一幅图，你通常先设置 *绘图单位* 通过命令 `\unitlength`，它必须在 `picture` 环境外使用。例如，如果你写
```latex
\setlength{\unitlength}{1cm}
```
绘图单位将被解释为 1cm 的倍数。默认单位是 1pt。
### 定义你的图形尺寸
其一般形式为 `picture` 环境如下
```latex
\begin{picture}(width, height)(Xoffset, Yoffset)
...
\end{picture}
```
其中
* `width` 和 `高度` 是以 `\unitlength`为单位的值，用于定义图形的尺寸。LaTeX 使用这些值创建一个框，其尺寸为
* 框（图形）宽度 = `width` × `\unitlength`
* 框（图形）高度 = `高度` × `\unitlength`
* `(Xoffset, Yoffset)` 是一个可选坐标，用于设置图形的原点（左下角），表示为相对于默认位置的 *偏移量* 。 `Xoffset` 和 `Yoffset` 也以当前 `\unitlength`.
请注意 `Xoffset` 和 `Yoffset` 的值所决定的单位表示，并不会影响 LaTeX 预留的空间量；也就是框的尺寸。
#### 理解图形尺寸
我们将创建两个图形，都使用 `\setlength{\unitlength}{1cm}` ，并且每个都具有一个 `width` 和 `高度` 为 3 个单位的
第一个图形使用默认原点 `(0,0)`:
```latex
\begin{picture}(3,3)
...
\end{picture}
```
第二个图形将原点偏移（平移） `(1,1)`:
```latex
\begin{picture}(3,3)(1,1)
...
\end{picture}
```
### 绘制图形
图形是通过一系列 `\put`, `\multiput`，或 `\qbezier` 命令创建的，这些命令生成构成图形或插图的各个“组件”（或“对象”）：
* `\put(x, y){*component*}` 绘制 `*component*` 在位置 `(x, y)`.
* `\multiput(x, y)(dx, dy){n}{*component*}` 绘制 `*component*` `n` 次：从位置 `(x, y)` 开始，并反复平移 `(dx, dy)` 以重新绘制 `*component*`.
* `\qbezier[n](x1, y1)(x, y)(x2, y2)`：绘制一条 [二次贝塞尔曲线](https://en.wikipedia.org/wiki/B%C3%A9zier_curve#Quadratic_B%C3%A9zier_curves) 其中：
* `n` 一个可选整数，用于确定绘制/生成曲线时所使用的点数
* `(x1, y1)` 是曲线的起点
* `(x2, y2)` 是曲线的终点
* `(x, y)` 表示（二次）贝塞尔曲线的控制点
一个 `*component*` 是一个图形元素，通常使用如下图形原语生成： `\line`, `\oval`, `\circle`, `\vector` 等等——参见 [LaTeX2e 非官方参考手册](https://latexref.xyz/picture.html) 或 [《LaTeX2ε 不太短的介绍》](https://tobi.oetiker.ch/lshort/lshort.pdf) （第 5 章）了解可用原语的详细信息。
**注意**： [`pict2e` 宏包](https://mirror.ox.ac.uk/sites/ctan.org/macros/latex/contrib/pict2e/pict2e.pdf) 扩展了原始的 `picture` 环境，提供若干用于绘制贝塞尔曲线的命令： `\bezier`, `\qbezier`, `\cbezier` 和 `\qbeziermax`.
### 理解偏移量和原点
在以下示例中， `\put` 命令用于绘制彩色点，以标示图形中的关键坐标（位置）。两个示例都使用 LaTeX 的 `\fbox` 命令在 LaTeX 为容纳我们的图形而创建的框周围绘制边框，显示 *边界框* 。
**示例 1：使用默认原点**
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\usepackage[dvipsnames]{xcolor}
\begin{document}
\setlength{\unitlength}{1cm}
\setlength{\fboxsep}{0pt}
这是我的图形\fbox{%
\begin{picture}(3,3)
\put(0,0){{\color{blue}\circle*{0.25}}\hbox{\kern3pt \texttt{(0,0)}}}
\put(3,3){{\color{red}\circle*{0.25}}\hbox{\kern3pt \texttt{(3,3)}}}
\end{picture}}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=understanding+picture+dimensions+example+1\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cusepackage%5Bdvipsnames%5D%7Bxcolor%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Csetlength%7B%5Cfboxsep%7D%7B0pt%7D%0A%0AThis+is+my+picture%5Cfbox%7B%25%0A%5Cbegin%7Bpicture%7D%283%2C3%29%0A%5Cput%280%2C0%29%7B%7B%5Ccolor%7Bblue%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt+%5Ctexttt%7B%280%2C0%29%7D%7D%7D%0A%5Cput%283%2C3%29%7B%7B%5Ccolor%7Bred%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt+%5Ctexttt%7B%283%2C3%29%7D%7D%7D%0A%5Cend%7Bpicture%7D%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
该 `\fbox` 命令在图形的边界框周围绘制边框，显示 LaTeX 预留的空间（区域）：
* 图形宽度 = `width` × `\unitlength` = 3 × 1cm = 3cm。
* 图形高度 = `高度` × `\unitlength` = 3 × 1cm = 3cm。
第一个示例表明，原点 `(0,0)`，位于 `\begin{picture}` 命令执行的位置，也就是文本“这是我的图形”之后紧接着的位置。此外，右上角位于 `(3,3)`， `(width,height)` 由以下参数给出的 `\begin{picture}(3,3)`.
**示例 2：将原点偏移 (1,1)**
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\usepackage[dvipsnames]{xcolor}
\begin{document}
\setlength{\unitlength}{1cm}
\setlength{\fboxsep}{0pt}
这是我的图形\fbox{%
\begin{picture}(3,3)(1,1)
\put(0,0){{\color{blue}\circle*{0.25}}\hbox{\kern3pt\texttt{(0,0)}}}
\put(1,1){{\color{orange}\circle*{0.25}}\hbox{\kern3pt\texttt{(1,1)}}}
\put(3,3){{\color{red}\circle*{0.25}}\hbox{\kern3pt\texttt{(3,3)}}}
\put(4,4){{\color{black}\circle*{0.25}}\hbox{\kern3pt\texttt{(4,4)}}}
\end{picture}}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=understanding+picture+dimensions+example+2\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cusepackage%5Bdvipsnames%5D%7Bxcolor%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Csetlength%7B%5Cfboxsep%7D%7B0pt%7D%0A%0AThis+is+my+picture%5Cfbox%7B%25%0A%5Cbegin%7Bpicture%7D%283%2C3%29%281%2C1%29%0A%5Cput%280%2C0%29%7B%7B%5Ccolor%7Bblue%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt%5Ctexttt%7B%280%2C0%29%7D%7D%7D%0A%5Cput%281%2C1%29%7B%7B%5Ccolor%7Borange%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt%5Ctexttt%7B%281%2C1%29%7D%7D%7D%0A%5Cput%283%2C3%29%7B%7B%5Ccolor%7Bred%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt%5Ctexttt%7B%283%2C3%29%7D%7D%7D%0A%5Cput%284%2C4%29%7B%7B%5Ccolor%7Bblack%7D%5Ccircle%2A%7B0.25%7D%7D%5Chbox%7B%5Ckern3pt%5Ctexttt%7B%284%2C4%29%7D%7D%7D%0A%5Cend%7Bpicture%7D%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
第二个示例展示了移动原点的效果，并突出了一些关键点：
* 由 `\fbox` 显示图形的边界框，也就是 LaTeX 创建的框的宽度和高度， *不受影响* ；移动原点并不会改变它：它仍然由 `(width,height)` 由以下参数给出的 `\begin{picture}(3,3)(1,1)`
* 图形宽度 = `width` × `\unitlength` = 3 × 1cm = 3cm
* 图形高度 = `高度` × `\unitlength` = 3 × 1cm = 3cm
* 绘图元素并不受 LaTeX 创建的区域（边界框尺寸）限制（裁剪）。例如，蓝点和 `(0,0)` 坐标被绘制在由 `\fbox`生成的边界线之外，该边界线表示边界框。
* 需要由用户自行确保绘图元素保持在边界框内，并且不覆盖周围文本。
* 原点， `(0,0)`，是 *不再* 位于文本“这是我的图形”之后紧接着的位置，也就是 `\begin{picture}` 命令执行的位置：原点现在向左移动 1 个单位，并向下移动 1 个单位
* 右上角现在位于 `(4,4)`
## picture 环境示例
### 来自 LaTeX2e 非官方参考手册的示例
该 [LaTeX2e 非官方参考手册](https://latexref.xyz/picture.html) 包含若干 `picture` 环境示例，其中一些在此重现，并附有可在 Overleaf 中打开的链接，方便你编辑和探索代码。
#### 示例 1：\vector 命令
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{1cm}
\begin{picture}(6,6) % picture box will be 6cm wide by 6cm tall
\put(0,0){\vector(2,1){4}} % for every 2 over this vector goes 1 up
\put(2,1){\makebox(0,0)[l]{\ first leg}}
\put(4,2){\vector(1,2){2}}
\put(5,4){\makebox(0,0)[l]{\ second leg}}
\put(0,0){\vector(1,1){6}}
\put(3,3){\makebox(0,0)[r]{sum\ }}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=picture+environment+example\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Cbegin%7Bpicture%7D%286%2C6%29++++++%25+picture+box+will+be+6cm+wide+by+6cm+tall%0A++%5Cput%280%2C0%29%7B%5Cvector%282%2C1%29%7B4%7D%7D++%25+for+every+2+over+this+vector+goes+1+up%0A++++%5Cput%282%2C1%29%7B%5Cmakebox%280%2C0%29%5Bl%5D%7B%5C+first+leg%7D%7D%0A++%5Cput%284%2C2%29%7B%5Cvector%281%2C2%29%7B2%7D%7D%0A++++%5Cput%285%2C4%29%7B%5Cmakebox%280%2C0%29%5Bl%5D%7B%5C+second+leg%7D%7D++%0A++%5Cput%280%2C0%29%7B%5Cvector%281%2C1%29%7B6%7D%7D%0A++++%5Cput%283%2C3%29%7B%5Cmakebox%280%2C0%29%5Br%5D%7Bsum%5C+%7D%7D++%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
#### 示例 2：\qbezier、\line、\vector、\thinlines 和 \thicklines 命令
注意 `\qbezier` 命令 *并未* 在 `\put{...}` 中使用，而其他原始命令，如 `\line`, `\vector` *已* 在 `\put{...}`.
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{1cm}
\begin{picture}(8,4)
\thinlines % Start with thin lines
\put(0,0){\vector(1,0){8}} % x axis
\put(0,0){\vector(0,1){4}} % y axis
\put(2,0){\line(0,1){3}} % left side
\put(4,0){\line(0,1){3.5}} % right side
\thicklines % Use thicker lines for the \qbezier commands
\qbezier(2,3)(2.5,2.9)(3,3.25)
\qbezier(3,3.25)(3.5,3.6)(4,3.5)
\thinlines % Back to using thin lines
\put(2,3){\line(4,1){2}}
\put(4.5,2.5){\framebox{Trapezoidal Rule}}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=qbezier+picture+environment+example\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Cbegin%7Bpicture%7D%288%2C4%29%0A++%5Cthinlines+%25+Start+with+thin+lines%0A++%5Cput%280%2C0%29%7B%5Cvector%281%2C0%29%7B8%7D%7D++%25+x+axis%0A++%5Cput%280%2C0%29%7B%5Cvector%280%2C1%29%7B4%7D%7D++%25+y+axis%0A++%5Cput%282%2C0%29%7B%5Cline%280%2C1%29%7B3%7D%7D++++%25+left+side%0A++%5Cput%284%2C0%29%7B%5Cline%280%2C1%29%7B3.5%7D%7D++%25+right+side%0A++%5Cthicklines+%25+Use+thicker+lines+for+the+%5Cqbezier+commands%0A++%5Cqbezier%282%2C3%29%282.5%2C2.9%29%283%2C3.25%29%0A++%5Cqbezier%283%2C3.25%29%283.5%2C3.6%29%284%2C3.5%29%0A++%5Cthinlines+%25+Back+to+using+thin+lines%0A++%5Cput%282%2C3%29%7B%5Cline%284%2C1%29%7B2%7D%7D%0A++%5Cput%284.5%2C2.5%29%7B%5Cframebox%7BTrapezoidal+Rule%7D%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
#### 示例 3：\multiput 和 \linethickness 命令
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{1cm}
\thicklines
\begin{picture}(10,10)
\linethickness{0.05mm}
\multiput(0,0)(1,0){10}{\line(0,1){10}}
\multiput(0,0)(0,1){10}{\line(1,0){10}}
\linethickness{0.5mm}
\multiput(0,0)(5,0){3}{\line(0,1){10}}
\multiput(0,0)(0,5){3}{\line(1,0){10}}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=multiput+command+picture+environment+example\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Cthicklines%0A%5Cbegin%7Bpicture%7D%2810%2C10%29%0A++%5Clinethickness%7B0.05mm%7D%0A++%5Cmultiput%280%2C0%29%281%2C0%29%7B10%7D%7B%5Cline%280%2C1%29%7B10%7D%7D+%0A++%5Cmultiput%280%2C0%29%280%2C1%29%7B10%7D%7B%5Cline%281%2C0%29%7B10%7D%7D%0A++%5Clinethickness%7B0.5mm%7D%0A++%5Cmultiput%280%2C0%29%285%2C0%29%7B3%7D%7B%5Cline%280%2C1%29%7B10%7D%7D%0A++%5Cmultiput%280%2C0%29%280%2C5%29%7B3%7D%7B%5Cline%281%2C0%29%7B10%7D%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
### 其他示例
#### 一个基本的贝塞尔曲线
下面的示例使用 `\qbezier` 用于绘制贝塞尔曲线的命令：
```latex
\qbezier(1,1)(5,5)(9,0.5)
```
请注意以下几点：
* 该 `\qbezier` 命令未在 `\put` 命令
* 贝塞尔曲线的起点是 `(1,1)`
* 贝塞尔曲线的终点是 `(9,0.5)`
* 贝塞尔曲线的控制点是 `(5,5)`
* 我们没有使用用于确定绘制/生成贝塞尔曲线时所用点数的可选整数
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{0.8cm}
\begin{picture}(10,5)
\thicklines
\qbezier(1,1)(5,5)(9,0.5)
\put(2,1){{Bézier curve}}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=multiput+command+picture+environment+example\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B0.8cm%7D%0A%5Cbegin%7Bpicture%7D%2810%2C5%29%0A%5Cthicklines%0A%5Cqbezier%281%2C1%29%285%2C5%29%289%2C0.5%29%0A%5Cput%282%2C1%29%7B%7BB%C3%A9zier+curve%7D%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
#### 椭圆、线条和圆
以下示例演示了 `\line`, `\circle` 和 `\oval` 命令——请注意它们如何 *已* 都在 `\put{...}` 命令：
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{1cm}
\thicklines
\begin{picture}(10,6)
\put(2,2.2){\line(1,0){6}}
\put(2,2.2){\circle{2}}
\put(6,2.2){\oval(4,2)[r]}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=picture+environment+example\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B1cm%7D%0A%5Cthicklines%0A%5Cbegin%7Bpicture%7D%2810%2C6%29%0A%5Cput%282%2C2.2%29%7B%5Cline%281%2C0%29%7B6%7D%7D%0A%5Cput%282%2C2.2%29%7B%5Ccircle%7B2%7D%7D%0A%5Cput%286%2C2.2%29%7B%5Coval%284%2C2%29%5Br%5D%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
下面是这些命令的说明：
* `\put(2,2.2){\line(1,0){6}}`：绘制一条线 `6` 个单位长，使用“方向向量” `(1,0)`
* `\put(6,2.2){\oval(4,2)[r]}`：绘制一个以该点为中心的椭圆 `(4,2)`。参数 `[r]` 是可选的，你可以使用 `r`, `l`, `t` 和 `b` 来显示椭圆的右、左、上或下部分。
* `\put(2,2.2){\circle{2}}`：绘制一个以该点为中心的圆 `(2,2.2)` 其直径为 `2`.
#### 组合线条、圆和文本
不同的基本元素可以组合成更复杂的图形。在这个示例中，若干线条和圆被组合成一个图形，并配有文本来标注各个点：
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{0.8cm}
\begin{picture}(12,4)
\thicklines
\put(8,3.3){{\footnotesize $3$-simplex}}
\put(9,3){\circle*{0.1}}
\put(8.3,2.9){$a_2$}
\put(8,1){\circle*{0.1}}
\put(7.7,0.5){$a_0$}
\put(10,1){\circle*{0.1}}
\put(9.7,0.5){$a_1$}
\put(11,1.66){\circle*{0.1}}
\put(11.1,1.5){$a_3$}
\put(9,3){\line(3,-2){2}}
\put(10,1){\line(3,2){1}}
\put(8,1){\line(1,0){2}}
\put(8,1){\line(1,2){1}}
\put(10,1){\line(-1,2){1}}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=understanding+picture+dimensions+example+1\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B0.8cm%7D%0A%5Cbegin%7Bpicture%7D%2812%2C4%29%0A%5Cthicklines%0A%5Cput%288%2C3.3%29%7B%7B%5Cfootnotesize+%243%24-simplex%7D%7D%0A%5Cput%289%2C3%29%7B%5Ccircle%2A%7B0.1%7D%7D%0A%5Cput%288.3%2C2.9%29%7B%24a_2%24%7D%0A%5Cput%288%2C1%29%7B%5Ccircle%2A%7B0.1%7D%7D%0A%5Cput%287.7%2C0.5%29%7B%24a_0%24%7D%0A%5Cput%2810%2C1%29%7B%5Ccircle%2A%7B0.1%7D%7D%0A%5Cput%289.7%2C0.5%29%7B%24a_1%24%7D%0A%5Cput%2811%2C1.66%29%7B%5Ccircle%2A%7B0.1%7D%7D%0A%5Cput%2811.1%2C1.5%29%7B%24a_3%24%7D%0A%5Cput%289%2C3%29%7B%5Cline%283%2C-2%29%7B2%7D%7D%0A%5Cput%2810%2C1%29%7B%5Cline%283%2C2%29%7B1%7D%7D%0A%5Cput%288%2C1%29%7B%5Cline%281%2C0%29%7B2%7D%7D%0A%5Cput%288%2C1%29%7B%5Cline%281%2C2%29%7B1%7D%7D%0A%5Cput%2810%2C1%29%7B%5Cline%28-1%2C2%29%7B1%7D%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
以下是所用一些命令的摘要：
* `\thicklines`：这会增加线条的粗细。 `\thinlines` 命令则起相反作用。
* `\put(8,3.3){{\footnotesize $3$-simplex}}`：文本“3-simplex”插入在点 `(8,3.3)`，字体大小设为 `\footnotesize`。同样的命令也用于标注每个点。
* `\put(9,3){\circle*{0.1}}`：这会绘制一个实心圆，圆心位于 `(9,3)` ，直径很小，为 `0.1` （绘图单位），因此可用作一个点。
* `\put(10,1){\line(3,2){1}}`：创建一条从 `(10,1)` 开始、沿着 `(3,2)` 方向绘制、长度为 1（绘图单位）的直线。
#### 使用箭头
箭头也可以在 `picture` 环境中使用，因此这里给出第二个示例：
```latex
\documentclass{article}
\usepackage[pdftex]{pict2e}
\begin{document}
\setlength{\unitlength}{0.20mm}
\begin{picture}(400,250)
\put(75,10){\line(1,0){130}}
\put(75,50){\line(1,0){130}}
\put(75,200){\line(1,0){130}}
\put(120,200){\vector(0,-1){150}}
\put(190,200){\vector(0,-1){190}}
\put(97,120){$\alpha$}
\put(170,120){$\beta$}
\put(220,195){upper state}
\put(220,45){lower state 1}
\put(220,5){lower state 2}
\end{picture}
\end{document}
```
[在 Overleaf 中打开此示例](https://www.overleaf.com/docs?engine=pdflatex\&snip_name=Example+of+arrows+in+LaTeX+picture+environment\&snip=%5Cdocumentclass%7Barticle%7D%0A%5Cusepackage%5Bpdftex%5D%7Bpict2e%7D%0A%5Cbegin%7Bdocument%7D%0A%5Csetlength%7B%5Cunitlength%7D%7B0.20mm%7D%0A%5Cbegin%7Bpicture%7D%28400%2C250%29%0A%5Cput%2875%2C10%29%7B%5Cline%281%2C0%29%7B130%7D%7D%0A%5Cput%2875%2C50%29%7B%5Cline%281%2C0%29%7B130%7D%7D%0A%5Cput%2875%2C200%29%7B%5Cline%281%2C0%29%7B130%7D%7D%0A%5Cput%28120%2C200%29%7B%5Cvector%280%2C-1%29%7B150%7D%7D%0A%5Cput%28190%2C200%29%7B%5Cvector%280%2C-1%29%7B190%7D%7D%0A%5Cput%2897%2C120%29%7B%24%5Calpha%24%7D%0A%5Cput%28170%2C120%29%7B%24%5Cbeta%24%7D%0A%5Cput%28220%2C195%29%7Bupper+state%7D%0A%5Cput%28220%2C45%29%7Blower+state+1%7D%0A%5Cput%28220%2C5%29%7Blower+state+2%7D%0A%5Cend%7Bpicture%7D%0A%5Cend%7Bdocument%7D)
此示例生成如下输出：
该 `\vector` 命令使用与 `\line`:
* `\put(120,200){\vector(0,-1){150}}`：绘制一条向量，其起点是 `(120,200)`，长度为 `150` ，绘制方向为 `(0,-1)`.
## 进一步阅读
更多信息请参见以下资源：
* [LaTeX2e 非官方参考手册](https://latexref.xyz/picture.html)
* [《LaTeX2ε 不太短的介绍》](https://tobi.oetiker.ch/lshort/lshort.pdf) （见第 5 章）
* [Wikibooks](https://en.wikibooks.org/wiki/LaTeX/Picture)
* [带有标签的提问 `picture-mode` 在 tex.stackexchange 上](https://tex.stackexchange.com/questions/tagged/picture-mode)
* [`pict2e` 包文档](https://mirror.ox.ac.uk/sites/ctan.org/macros/latex/contrib/pict2e/pict2e.pdf)
* [TikZ 宏包](/latex/zh-cn/tu-xing-he-biao-ge/05-tikz-package.md)
* [Pgfplots 宏包](/latex/zh-cn/te-ding-ling-yu/08-pgfplots-package.md)
* [图片和表格的定位](/latex/zh-cn/tu-xing-he-biao-ge/02-positioning-images-and-tables.md)
* [表格和图形列表](/latex/zh-cn/tu-xing-he-biao-ge/03-lists-of-tables-and-figures.md)
---
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