How to solve the intersection truncation problem of multiple \draw[thick, color=xxx] commands by color？

Question

I was learning foreach command in TIKZ and I want to plot the style and the color shown as below.

After consulting the doc of pgfplots, I achieve it by the code as below:

\documentclass{ctexart}
\usepackage{tikz}
\usepackage{xfp}
\usepackage{pgfplots}
\newcounter{cnt}
\setcounter{cnt}{1}
\begin{document}
    \begin{tikzpicture}
        \pgfmathtruncatemacro{\N}{4}
        \foreach \x[
            count=\n,
            evaluate=\n as \u using int(2*\n-1),
            evaluate=\n as \v using int(2*\n),
            ] in {1,...,\N}{
            % \draw (1-\n,1-\n) --++ (\u,0) --++ (0,\u) --++ (-\v,0) --++ (0,-\v);
            % \draw [thick,color = red] (1-\n,1-\n) --++ (\u,0);
            % \draw [thick,color = yellow] (1-\n+\u,1-\n) --++ (0,\u);
            % \draw [thick,color = blue] (1-\n+\u,1-\n+\u) --++ (-\v,0);
            % \draw [thick,color = green] (1-\n+\u-\v,1-\n+\u) --++ (0,-\v);
            \draw [thick,color = red] (1-\n,1-\n) --++(\u,0);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = yellow] (\macrox,\macroy) --++ (0,\u);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = blue] (\macrox,\macroy) --++ (-\v,0);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = green] (\macrox,\macroy) --++ (0,-\v);
        }
    \end{tikzpicture}
\end{document}

Unfortunely, when I enlarge the pdf, and I found that the corner of two path didn't connect with thick lines(Shown as below)

To use the \foreach and change the color in the loop I have to use four \draw commands, it cause the problem. Although it can be fixed with \draw (1-\n,1-\n) --++ (\u,0) --++ (0,\u) --++ (-\v,0) --++ (0,-\v); But it couldn't change the color.

It is a dilemma! Maybe it can be configured to set the tail of each path to be an acute Angle of 45°, which in the junction it can reach a better lookings. But I don;t know how to code by PGF/TIKZ. Thanks!

Answer 1

\documentclass[tikz, border=1cm]{standalone}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}[
ultra thick,
left/.tip={Butt Cap[sep=0pt -1]Rectangle[sep=0pt -0.5, slant=-1 ,width=0pt 1, length=0pt 2]},
right/.tip={Butt Cap[sep=0pt -1]Rectangle[sep=0pt -0.5, slant=1 ,width=0pt 1, length=0pt 2]},
]
\draw[green, -right] (0,0.5) -- (0,1);
\draw[blue, left-right] (0,1) -- (1,1);
\draw[yellow, left-right] (1,1) -- (1,0);
\draw[red, left-] (1,0) -- (0.5,0);
\end{tikzpicture}
\end{document}

Answer 2

This is an option using areas, since the finish you require could not be done with separate draw instructions, as far as I know, but you can quickly add a couple of additional points to generate a trapezoidal shape and instead of using the last coordinates you can define For each one, a temporary storage coordinate, as in this case it is temp, then draw from this the trapezoid that follows, then change from line to fill, with this you could even use fadings or gradients for more effects.

RESULT PAGE 1:

RESULT PAGE 2:

MWE:

\documentclass[tikz,border=5pt]{standalone}
\usetikzlibrary{shadings}
\begin{document}
    \begin{tikzpicture}
        \def\N{4}
        \def\Thickness{4pt}
        \foreach \x[
            count=\n,
            evaluate=\n as \u using int(2*\n-1),
            evaluate=\n as \v using int(2*\n),
        ] in {1,...,\N}{
            \fill [color = red] (1-\n,1-\n)--++(45:\Thickness)--++(\u,0) --++(-45:\Thickness) coordinate (temp) -- cycle;
            \fill [color = yellow] (temp)--++(135:\Thickness) --++ (0,\u)--++(45:\Thickness) coordinate (temp) -- cycle;
            \fill [color = blue] (temp)--++(-135:\Thickness)--++ (-\v,0)--++(135:\Thickness) coordinate (temp) -- cycle;
            \fill [color = green] (temp)--++(-45:\Thickness)  --++ (0,-\v)--++(-135:\Thickness) -- cycle;
        }
    \end{tikzpicture}
    
    \begin{tikzpicture}
        \def\N{4}
        \def\Thickness{4pt}
        \foreach \x[
        count=\n,
        evaluate=\n as \u using int(2*\n-1),
        evaluate=\n as \v using int(2*\n),
        ] in {1,...,\N}{
            \shade [left color=red, right color=yellow] (1-\n,1-\n)--++(45:\Thickness)--++(\u,0) --++(-45:\Thickness) coordinate (temp) -- cycle;
            \shade [top color=blue, bottom color=yellow] (temp)--++(135:\Thickness) --++ (0,\u)--++(45:\Thickness) coordinate (temp) -- cycle;
            \shade [left color=green, right color=blue] (temp)--++(-135:\Thickness)--++ (-\v,0)--++(135:\Thickness) coordinate (temp) -- cycle;
            \shade [top color=green, bottom color=red] (temp)--++(-45:\Thickness)  --++ (0,-\v)--++(-135:\Thickness) -- cycle;
        }
    \end{tikzpicture}
\end{document}

Answer 3

There is no native way of making bevelled segments with Tikz. To hide this broken line effect, I increase the length of certain strokes by half the thickness of your line, which measures 0.8pt (thick), so I make it 0.4pt longer.

\documentclass{ctexart}
\usepackage{tikz}
\usepackage{xfp}
\usepackage{pgfplots}
\newcounter{cnt}
\setcounter{cnt}{1}
\begin{document}
    \begin{tikzpicture}
        \pgfmathtruncatemacro{\N}{4}
        \foreach \x[
            count=\n,
            evaluate=\n as \u using int(2*\n-1),
            evaluate=\n as \v using int(2*\n),
            ] in {1,...,\N}{
            % \draw (1-\n,1-\n) --++ (\u,0) --++ (0,\u) --++ (-\v,0) --++ (0,-\v);
            % \draw [thick,color = red] (1-\n,1-\n) --++ (\u,0);
            % \draw [thick,color = yellow] (1-\n+\u,1-\n) --++ (0,\u);
            % \draw [thick,color = blue] (1-\n+\u,1-\n+\u) --++ (-\v,0);
            % \draw [thick,color = green] (1-\n+\u-\v,1-\n+\u) --++ (0,-\v);
            \draw [thick,color = red] (1-\n,1-\n) --++(\u,0);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = yellow] (\macrox,\macroy -.4pt) --++ (0,\u);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = blue] (\macrox +.4pt,\macroy) --++ (-\v,0);
            \pgfgetlastxy{\macrox}{\macroy}
            \draw [thick,color = green] (\macrox,\macroy +.4pt) --++ (0,-\v);
        }
        
        
    \end{tikzpicture}
\end{document}