# Draw Shadow to a plan

I want to draw something like this picture:

As the shadow is curved, i decided to draw a trapezium and then draw a shadow on it. The problem is i want the coordinates of the trapezium corners. here is my code

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}

\usetikzlibrary{shapes.symbols}
\definecolor{mycolor}{rgb}{0.55,0.9,0.55}
\begin{document}
\begin{tikzpicture}[y=.3cm, x=1.2cm,font=\sffamily]
%\node[circle,fill=black] at (0,0) {};
\node[circle,fill=black] at (5.59,-8.3) {};
\node[circle,fill=black] at (-2.1,-8.3) {};
\node[circle,fill=black] at (-5.59,8.3) {};
%rotate = -140
\node[trapezium, minimum width=10cm,trapezium left angle=130, trapezium right angle=50, minimum height = 5cm,fill=mycolor]  at (0,0){};

\filldraw[fill=gray]
(5.55,-8.3) -- (5.55,-8) -- (-2.1,-8) -- (-5.6,8) -- (-5.59,8.3) -- (-2.1,-8.3) -- cycle;

\end{tikzpicture}
\end{document}


I tried to figure out the coordinates by drawing circles in the arbitrary locations and correct them manually.

Is there away to find these coordinates accurately?, and am i thinking a hard way and there is an easy way to do this?.

• Do you require your shape to be a node? If not, you can simply draw it giving the required coordinates. If you need to reuse that shape at different locations/angles you can create a pic with it. Commented Jul 22, 2015 at 10:27
• I want to add this part to a larger tikz picture in different angles. can i do it as a 4 points not as a node?. Commented Jul 22, 2015 at 10:35

You can draw the shape inside a pic definition, and then use that pic to reuse the figure at any place/scale/angle. This pic feature requires a recent version of Tikz/PGF.

This is an example:

\documentclass{article}
\usepackage{tikz}

\tikzset{
patch/.pic = {
\draw[fill=green!30] (-2,0) to[out=10, in=190] (0,1)
to (2,0)
to[out=-140, in=45] (0,-1)
to[out=145, in=-35] (-2,0)
-- cycle;
\draw[fill=black!60] (0,-1)
to[out=145, in=-35] (-2,0)
-- (-2,-.2) -- (0,-1.5) -- cycle;
\draw[fill=black!30] (2,0)
to[out=-140, in=45] (0,-1)
-- (0,-1.5) -- (2, -.2) -- cycle;
},
}

\begin{document}
\begin{tikzpicture}
\pic at (0,0) {patch};
\pic[scale=0.5, rotate=20] at (2,2) {patch};
\pic[scale=0.5, rotate=-20] at (-2,2) {patch};
\end{tikzpicture}
\end{document}


This is the result:

• WOW. would you please explain how in and out work in this code. Thanks alot. Commented Jul 22, 2015 at 11:06
• They just refer to the angle of entry and departure for a particular path. Commented Jul 22, 2015 at 11:10