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填充 tikz 命令

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填充 tikz 命令

我对 Tikz 中的填充命令有疑问。

我的问题是虚线区域在所有方向上都超出/或缩小了。我希望虚线区域能够精确填充线周围的区域。

有没有什么帮助可以调整填充区域？谢谢

在此处输入图片描述

代码如下

\documentclass{report}
\usepackage{tikz,pgfplots}
\usepgfplotslibrary{fillbetween}


\begin{document}
            \begin{tikzpicture}
                \draw[gray!50, thin, step=0.5] (-1,-1) grid (5,4);
                \draw[very thick,->] (-1,0) -- (5,0) node[right] {$x_1$};
                \draw[very thick,->] (0,-1) -- (0,5) node[above] {$x_2$};
                
                % absice des axes 
                \foreach \x in {-1,...,5} \draw (\x,0.05) -- (\x,-0.05) node[below] {\tiny\x};
                \foreach \y in {-2.5,...,4} \draw (-0.05,\y) -- (0.05,\y) node[right] {\tiny\y};
                
                %   \fill[blue!50!cyan,opacity=0.3] (8/3,1/3) -- (1,2) -- (13/3,11/3) -- cycle;
                
                \draw[name path=line1] (2,4) -- node[above right,sloped] {\tiny$2x_A+x_B\leq8$} (4.5,-1);   % desig une ligne
                \fill [blue!50!cyan, above ,opacity=0.3, domain=-1:2, variable=\x]
                (5,4)
                -- plot ({\x}, {8 -2* \x})
                --  (4.5,-1)
                --  (5,-1)
                -- cycle;
                
                
                \draw[name path=line2] (-1,3) -- node[above ,sloped] {\tiny$x_B\geq3$} (5,3);   % desig une ligne
                \fill [green!50!cyan, above ,opacity=0.3, domain=-1:2, variable=\x]
                (-1, 4)
                -- plot ({\x}, {3})
                -- (5, 4)
                -- cycle;
                
                
                \draw[name path=line3] (-1,4) -- node[below left,sloped] {\tiny$x_1+2x_B\leq7$} (5,1);   % design line  
                \fill [red!50!cyan, above ,opacity=0.3, variable=\x]
                (-1,4)
                -- plot ({\x}, {7/2 - (1/2)*\x})
                -- (5,4)
                -- cycle;
                
                
                \draw[name path=line3] (-1,0) -- node[above left,sloped] {\tiny$x_A\geq0$} (5,0);   % design line   
                \fill [red!50!cyan, above ,opacity=0.3, variable=\x]
                (-1,-1)
                -- plot ({\x}, {0})
                -- (5,-1)
                -- cycle;
                
                
                
                \draw[name path=line3] (0,-1) -- node[above left,sloped] {\tiny$x_B\geq0$} (0,4);   % design line   
                \fill [red!50!cyan, above ,opacity=0.3, variable=\x]
                (-1,-1)
                -- plot ({0}, {\x})
                -- (-1,4)
                -- cycle;
                
    \end{tikzpicture}

        
\end{document}

欢迎提出任何建议

答案1

这是您图表的实现。请注意，实现它的方法有很多种，其中一些方法比其他方法更有效。

我将仅绘制一个区域来解释我是如何做到的：

填充区域

我保留了您的网格和轴。我只是给出了 x 轴和 y 轴的名称路径。

我用的是intersectionstikz 库允许计算命名线之间的交点。为此，我需要定义几条线。在下面的代码中，您可以看到我如何定义它们。最重要的部分是

\path [name intersections={of=line1 and line2, by=pt-of-intersection}] (1,0) -- (pt-of-intersection);

代码

\documentclass{article}
\usepackage{tikz,pgfplots}
\usetikzlibrary{intersections}

\begin{document}
\begin{tikzpicture}
% The grid
\draw[gray!50, thin, step=0.5] (-1,-1) grid (5,4);
\draw[name path = axis-x, very thick,->] (-1,0) -- (5,0) node[right] {$x_1$};
\draw[name path = axis-y, very thick,->] (0,-1) -- (0,5) node[above] {$x_2$};

% the axes' ticks
\foreach \x in {-1,...,5} \draw (\x,0.05) -- (\x,-0.05) node[below] {\tiny\x};
\foreach \y in {-2.5,...,4} \draw (-0.05,\y) -- (0.05,\y) node[right] {\tiny\y};


% draw the line and name it line1
\draw[name path=line1] (3,4) -- node[above right,sloped] {\tiny$2x_A+x_B\leq8$} (4.5,-1);
% draw define an asymptote at y=4 but don't draw it
\path [name path = asymptote] (-1,4)--(5,4);
% compute intersection of the two lines named asymptote and line1, the output is named y-cross
\path [name intersections={of=asymptote  and line1, by=y-cross}];
% compute intersection of the two lines named axis-x and line1, the output is named x-cross
\path [name intersections={of=axis-x and line1, by=x-cross}];
% fill the spaec between the 4 points
\fill [blue!50!cyan,opacity=0.3](y-cross) -- (x-cross)-- (5,0)-- (5,4);
\end{tikzpicture}

\end{document}

如果你理解了这一点，那么你应该能够自己完成另一件事。这回答了你的问题吗？

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