PGF automatic determined vertical distance between tree nodes / level

Question

I am trying to draw a tree overview and got an example from http://www.texample.net. But I have a problem with the vertical distance between the nodes (levels). Is there a way how tikz can automatically determine a distance so that there is no overlapping. Using e.g. "level distance=x.yem" for each node is a lot of work for large trees. Below a running example for a small part of the tree.

            \documentclass[paper=a4]{report}
            \usepackage[utf8]{inputenc} % UTF8 encoding

            \usepackage{pgfplots}
            \pgfplotsset{compat=newest}
            \pgfplotsset{plot coordinates/math parser=false}
            \usetikzlibrary{arrows,shapes,positioning,shadows,trees}

            \begin{document}



            \tikzset{
                basic/.style  = {draw, font=\sffamily, rectangle},
                root/.style   = {basic, rounded corners=6pt, thin, align=center,
                                                 fill=blue!60,text width=0.5\textwidth},
                level 2/.style = {basic, rounded corners=6pt, thin,align=center, fill=green!60,text width=0.3\textwidth},
                level 3/.style = {basic, rounded corners=2pt, thin, align=center, fill=pink!60,text width=0.2\textwidth},
            }

            \begin{tikzpicture}[level 1/.style={sibling distance=40mm},
                edge from parent/.style={->,draw},
                >=latex]

            % root of the the initial tree, level 1
            \node[root]
            [level distance=30mm]
            {Some loss calculation models}
            % The first level, as children of the initial tree
                child {node[level 2] (c1) {ALmann based models (analytical)}}
                child {node[level 2] (c2) {Loss separation stuff stuff}}
                child {node[level 2] (c3) {Mathematical models and others}};

            % The second level, relatively positioned nodes
            \begin{scope}[every node/.style={level 3}]
            \node [below of = c1, xshift=15pt] (c11) {Mathematic stuff with very long name};
            \node [below of = c11] (c12) {Mathematic2 other long name};
            \node [below of = c12] (c13){Mathematic3 short};
            \node [below of = c13] (c13){Mathematic4 meadium size name};

            \end{scope}

            % lines from each level 1 node to every one of its "children"
            \foreach \value in {1,2,3}
                \draw[->] (c1.195) |- (c1\value.west);

            \end{tikzpicture}
            \end{document}

Answer 1

If you don't want to wait for TiKZ 3 and its graphdrawing library a valid option could be forest package. It automaticaly computes distances between nodes according their sizes.

Next code shows a starting point for a tree more or less similar to yours. You will need to read its manual to know how to adjust vertical subtree under its parent. You can also find help looking at previous questions in TX.SX about trees with and without forest.

\documentclass[tikz,border=3mm]{standalone}
\usepackage[utf8]{inputenc} % UTF8 encoding

\usepackage{forest}

\begin{document}
    \tikzset{basic/.style = {draw, font=\sffamily, rectangle},
            root/.style = {basic, rounded corners=6pt, thin,
                 align=center, fill=blue!60, 
                 text width=0.5\textwidth},
            level 2/.style = {basic, rounded corners=6pt, thin, 
                   align=center, fill=green!60,
                   text width=0.3\textwidth},
            level 3/.style = {basic, rounded corners=2pt, thin,
                   align=center, fill=pink!60,
                   text width=0.2\textwidth},
            }

\begin{forest}
% root of the the initial tree, level 1
[Some loss calculation models, root, for tree={level 2}
% The first level, as children of the initial tree
     [Almann based models (analytical), 
            for descendants={level 3, child anchor=west}, 
            for tree={ grow'=east }, calign=first
% The second level
        [Mathematic stuff with very long name]
        [Mathematic2 other long name]
        [Mathematic3 short]
        [Mathematic4 meadium size name]]
     [Loss separation stuff stuff]
     [Mathematical models and others]]
\end{forest}

\end{document}