# Asymmetric behavior of TikZ fadings

I am a bit confused about the behavior of TikZ fadings. Here is my MWE

\documentclass{article}
\usepackage{tikz}

\begin{scope}[transform canvas={rotate=#2},#1]
(40:1.2) --(40:1.3) --
(45:1.1) -- (40:0.9) -- (40:1) arc  (40:-40:1 and 1);
\end{scope}
}

\begin{scope}[transform canvas={rotate=#2},#1]
(-40:1.2) --(-40:1.3) --
(-45:1.1) -- (-40:0.9) -- (-40:1) arc   (-40:40:1 and 1);
\end{scope}
}

\begin{document}

\hspace*{3cm}

\end{document}


The left arrow is as I expect it to be, it fades away towards the "southern" direction. However, the second arrow, which is just the reverse of the first one, fades away towards the outer regions. I'd like to understand why that happens, and how to fix this.

In the left case, the shading is from top (gray) to bottom (white). The fading to south follows this direction and increases the effect.

In the right case, the shading angle needs to be fixed by shading angle=180 to get a shading from bottom (gray) to top (white). Then, the effect is increased by fading to north.

\documentclass{article}
\usepackage{tikz}

\begin{scope}[transform canvas={rotate=#2},#1]
(-40:1) -- (-40:1.2) arc (-40:40:1.2 and 1.2) --
(40:1.2) -- (40:1.3) --
(45:1.1) -- (40:0.9) -- (40:1) arc (40:-40:1 and 1);
\end{scope}%
}

\begin{scope}[transform canvas={rotate=#2},#1]
(40:1) -- (40:1.2) arc (40:-40:1.2 and 1.2) --
(-40:1.2) -- (-40:1.3) --
(-45:1.1) -- (-40:0.9) -- (-40:1) arc (-40:40:1 and 1);
\end{scope}%
}

\begin{document}


• Thanks a lot! Then my interpretation of path fading= was incorrect. BTW, it also shows correctly on preview, a tool on Mac OS. – marmot Jan 7 '18 at 3:42