完全在内部的遮光网格

Question

我在一个小方块网格上画了一个椭圆，我需要对椭圆内的方块进行着色，有没有办法不用对每个方块逐个进行着色？下面是我运行以下代码时得到的结果 以下是代码：

\documentclass[10pt]{article}
\usepackage{pgf,tikz}
\usepackage{mathrsfs}
\usetikzlibrary{arrows}
\pagestyle{empty}
\begin{document}
\definecolor{cqcqcq}{rgb}{0.7529411764705882,0.7529411764705882,0.7529411764705882}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
\draw [color=cqcqcq,, xstep=0.2cm,ystep=0.2cm] (1.6545364855997213,0.21463161817165122) grid (10.69837464681328,7.590037566885466);
\clip(1.6545364855997213,0.21463161817165122) rectangle (10.69837464681328,7.590037566885466);
\draw [rotate around={90.:(5.,4.)}] (5.,3.) ellipse (2.5617375054936047cm and 1.6007807617074208cm);
\end{tikzpicture}
\end{document}

但我需要我的图表看起来像这样：

Answer 1

问题是，普通的裁剪不起作用，因为裁剪对网格一无所知。下面的示例将裁剪与椭圆组合为裁剪区域，并排除与椭圆相交的单元格。

\documentclass[10pt]{article}
\usepackage{tikz}
\usetikzlibrary{intersections}
\usepackage{xcolor}
\pagestyle{empty}

\begin{document}
\definecolor{cqcqcq}{RGB}{192,192,192}
\colorlet{square}{blue!75!white}

\begin{tikzpicture}

  \def\xmin{3.8}
  \def\xmax{8.2}
  \def\ymin{1}
  \def\ymax{7}

  \def\EllipsePath{%
    [rotate around={90:(5, 4)}]
    (5, 3) ellipse (2.5617375054936047cm and 1.6007807617074208cm)%
  }
  \path[name path=ellipse]\EllipsePath;

  \global\let\FillList\empty

  \foreach \x in {4.4, 4.6, ..., 7.6} {
    \foreach \y in {1.4, 1.6, ..., 6.4} {
      \path[name path=square] (\x, \y) rectangle ++(.2, .2);
      \path[name intersections={
          of=ellipse and square,
          total=\t,
      }]
        \pgfextra{
          \ifnum\t=0 %
            \xdef\FillList{%
              \FillList
              \ifx\FillList\empty\else,\fi
              \x/\y%
            }%
          \fi
        }
      ;
    }
  }
  \begin{scope}
    \clip\EllipsePath;
    \fill[square]
      \foreach \x/\y in \FillList {
        (\x, \y) rectangle ++(.2, .2)
      }
    ;
  \end{scope}

  \draw[color=cqcqcq, step=.2]
    (\xmin, \ymin) grid (\xmax, \ymax)
    (\xmin, \ymin) rectangle (\xmax, \ymax)
  ;
  \clip (\xmin, \ymin) rectangle (\xmax, \ymax);
  \draw\EllipsePath;
\end{tikzpicture}
\end{document}

注意：编译需要相当长的时间。