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它们是不是平行的？

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它们是不是平行的？

视觉错觉很有趣，所以我认为列出使用 MetaPost、PGF/TikZ、PS-Tricks 或 Asymptote 设计的视觉错觉列表是个好主意。每个条目都应显示一个视觉错觉以及制作它所需的代码。

答案1

别盯着这个看太久。

\documentclass{standalone}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}
  \fill[color=black!40!white] (-6,-6) rectangle (6,6);
  \foreach \n/\r/\twist in {70/5/12,56/4/-12,42/3/12,28/2/-12}{
    \foreach \m in {1,3,...,\n}
      \draw [thick,color=white,shift={(360/\n*\m:\r)},rotate=\twist+360/\n*\m]
        (-.15,-.15) rectangle (.15,.15);
    \foreach \m in {2,4,...,\n}
      \draw [thick,color=black,shift={(360/\n*\m:\r)},rotate=\twist+360/\n*\m]
        (-.15,-.15) rectangle (.15,.15);
    }
\end{tikzpicture}

\end{document}

在此处输入图片描述

答案2

以下图片均无耻地抄袭自MetaFun 手册并由 Hans Hagen 编码。标题是：通过改变空间结构来控制对比度。图片来源于心理学家库尔特·考夫卡。

结果

\starttext

\startuseMPgraphic{first}
  numeric height, width, radius, gap ; gap := 1mm ;
  height = 2.5cm ; width := height/2 ; radius := height/2.5 ;
  color mainshade, leftshade, rightshade, centershade ;
  mainshade   := \MPcolor{lightblue} ;
  leftshade := .9mainshade ; rightshade := .5mainshade ;
  centershade := .5[leftshade,rightshade] ;
  fill unitsquare xyscaled ( width,height) withcolor leftshade ;
  fill unitsquare xyscaled (-width,height) withcolor rightshade ;
  draw (fullcircle scaled radius) shifted (0,height/2)
  withpen pencircle scaled (radius/2) withcolor centershade ;
\stopuseMPgraphic

\startuseMPgraphic{second}
  \includeMPgraphic{first}
  interim linecap := butt ; pickup pencircle scaled gap ;
  draw (0,0) -- (0,height) withcolor white ;
\stopuseMPgraphic


\startuseMPgraphic{third}
  \includeMPgraphic{first}
  picture p, q ; p := q := currentpicture ;
  clip p to unitsquare xscaled width yscaled height ;
  clip q to unitsquare xscaled -width yscaled height ;
  currentpicture := p ;
  addto currentpicture also q shifted (0,radius/2) ;
\stopuseMPgraphic

\useMPgraphic{first}
\useMPgraphic{second}
\useMPgraphic{third}

\stoptext

答案3

两个橙色圆圈的半径相同——这是艾宾浩斯错觉

在此处输入图片描述

% arara: pdflatex
% !arara: indent: {overwrite: yes}
\documentclass{standalone}

\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[baseline=(X.base)]
    \node[circle,fill=orange,draw=orange,minimum size=2cm] (X) at (0,0) {};
    \foreach \i in {0,60,...,330}{
        \filldraw[blue!50!white]  (\i:3.4) circle (1.6);}
\end{tikzpicture}
\hspace{1cm}
\begin{tikzpicture}[baseline=(X.base)]
    \node[circle,fill=orange,draw=orange,minimum size=2cm] (X) at (0,0) {};
    \foreach \i in {0,45,...,360}{
        \filldraw[blue!50!white]  (\i:1.5)  circle (.4);}
\end{tikzpicture}
\end{document}

答案4

它们是不是平行的？

非常受欢迎的一个。

行与行之间不匹配的垂直线会造成它们之间的线不平行的错觉。NetLogo 模型库：视觉错觉

相似之处

代码

\documentclass[tikz]{standalone}
\usetikzlibrary{calc}
\begin{document}
    \pagecolor{gray}
    \begin{tikzpicture}
        \pgfmathsetmacro{\offsety}{.05};
        \foreach \y / \offsetx in {0/0.3,1/0.5,2/0.3,3/0,4/0.3,5/0.5,6/0.3,7/0,8/0.3}
            \foreach \x in {0,...,10}{%
                \pgfmathifthenelse{mod(\x,2) == 0}{"black"}{"white"}
                %\ifodd\x \def\squarecolor{white} \else \def\squarecolor{black} \fi %Other way, use \squarecolor inside fill options
                \fill[\pgfmathresult] ($(\x,\y)+(\offsetx,\offsety*\y)$) rectangle +(1,1);
            }
    \end{tikzpicture}
\end{document}

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