Graphviz Dot Edge Ports for Family Tree

Question

I am very close to being able to generate a family tree that doesn't look terrible, but I'm running into the following problem.

//file: tree.dot
digraph {
    edge [dir=none];
    node [
        fillcolor="black",fixedsize=true,shape=box,
        style="rounded,filled",width=2.0
    ];
    splines=ortho;
    // GEN -01
    {
        rank=same; rankdir=LR;
        "Grandfather" [regular=0];
        m0002 [
            label="",shape=diamond,regular=0,height=0.25,
            width=0.25,style="filled",
        ];
        "Grandmother" [regular=0];
        {
            rank=same; rankdir=LR;
            "Grandfather" -> m0002 -> "Grandmother";
        }
    }
    m0002 -> c0001;
    // GEN  00
    {
        rank=same; rankdir=LR;
        c0000 [
            label="",shape=circle, regular=0, height=0.05,
            width=0.05,style="filled"
        ];
        c0001 [
            label="",shape=circle, regular=0, height=0.05,
            width=0.05,style="filled"
        ];
        c0002 [
            label="",shape=circle, regular=0, height=0.05,
            width=0.05, style="filled"
        ];
        {
            rank=same; rankdir=LR;
            c0000 -> c0001 -> c0002;
        }
    }
    {
        rank=same; rankdir=LR;
        "Son 1" [regular=0];
        "Daughter 1" [regular=0];
        "Son 2" [regular=0];
        m0000 [
            label="",shape=diamond,regular=0,height=0.25,
            width=0.25,style="filled"
        ];
        "Other Daughter 1" [regular=0];
        "Other Son 1" [regular=0];
        "Other Other Son 1" [regular=0];
        m0001 [
            label="",shape=diamond,regular=0,height=0.25,
            width=0.25, style="filled"
        ];
        "Other Daughter 2" [regular=0];
        {
            rank=same; rankdir=LR;
            "Son 2" -> m0000 -> "Other Daughter 1";
            "Other Other Son 1" -> m0001 -> "Other Daughter 2";
        }
    }
    c0000 -> "Son 1";
    c0001 -> "Daughter 1";
    c0002 -> "Son 2";
}

The above code produces this image, which has edges to Son 1 and Son 2 that look weird. I ran it with dot -Tpng tree.dot. When I run the same code here, I get the expected output.

Am I doing something wrong? How can I get the expected output without using the web interface (I will have potentially hundreds of nodes)? In other words, how can I get c0000 and c0002 to line up with the center of Son 1 and Son 2, respectively, so that their edges attach to the center top of the nodes?

Thanks in advance for your help!

Answer 1

You can specify where the edge connects using ports which use compass directions, n, s, e, w, nw, ne, sw, se.

Changing the following lines at the end of your dot file to include ports.

    c0000 -> "Son 1" [headport=ne];
    c0002 -> "Son 2":nw; // Shorthand for [headport=nw]

results in this image

This doesn't put the edges dead center, and changing the port locations to n doesn't work. But it no longer has edges pointing to an empty corner like your original. Part of GraphViz's utility is the autolayout but sometimes it seems to override user decisions (or is a bug).