# Find coordinate along bezier curve in Tikz

Let's say I defined a Bezier curve in Tikz:

\documentclass{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
\draw (0,0) .. controls (1,2) and  (2,-1) .. (4,0);
\end{tikzpicture}
\end{document}


I want to find coordinates along the curve, e.g. at 30% and 60% along the curve. I want to indicate their position with a red dot and draw arrows, starting at the coordinates, into different directions.

Is their a simple command that returns coordinates along a Bezier curve? Thank you.

You can use markings on any path including a bezier curve. mark=at position 0.30 means a marking 30% along the path.

\documentclass[border=0.2 cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.markings,arrows}
\begin{document}
\begin{tikzpicture}[%
decoration={markings,
mark=at position 0.30 with {\coordinate (A); \fill[red] circle [radius=2pt];},
mark=at position 0.60 with {\coordinate (B); \fill[red] circle [radius=2pt];}
}]

\draw[postaction={decorate}] (0,0) .. controls (1,2) and  (2,-1) .. (4,0);
\draw[->] (A) -- (1,1);
\draw[->] (B) -- (2,2);
\end{tikzpicture}
\end{document}


• This is exactly what I was looking for. Thanks a lot! :) – miga89 Jan 23 '17 at 5:03