when using arrows with Triangle Caps, tikz draws the part surrounding the junction between the line and the tip twice. This leads to unwanted results when using opacity; in addition, the part appended to the tip is not bendable.
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows,arrows.meta}
\begin{document}
\tikz {
\draw [line width=10mm,opacity=0.5,-{Triangle Cap[]}] (0,0) -- (6,0);
\draw [line width=7mm,opacity=0.5,-{Triangle Cap[]}] (0,1)
.. controls (1.5,0.5) and (1,4) .. (2,4);
}
\end{document}
Result:

Any thoughts, solutions?
Thanks in advance!
uzahnd
\begin{scope}[transparency group, opacity=0.5] ... \end{scope}– Jake Feb 18 '15 at 12:49