具有水平和垂直组合布局的可折叠树

我正在尝试在 D3 中创建一个可折叠树，它结合了水平（第一级和第二级）和垂直（3+级）布局。这里有一个jsfiddle http://jsfiddle.net/artemkolotilkin/z7tb23Lo/到目前为止我所得到的。除了一件事之外，它几乎就在那里。当两个同级部分展开时，它们之间的距离会增加得超过应有的距离。

我相信发生这种情况是因为 D3 认为子元素将以水平方式定位，因此它为它们分配更多空间，但我在代码中覆盖它们的位置，以便它们垂直显示。我觉得我现在需要重写计算父节点之间距离的函数，但无法弄清楚是哪一个。

这是我的 JS 代码：

var margin = {
    top: 20,
    right: 20,
    bottom: 20,
    left: 20
},
width = 1140 - margin.right - margin.left,
    height = 800 - margin.top - margin.bottom;

var i = 0,
    duration = 750;

var tree = d3.layout.tree()
    .size([height, width]);

var diagonal = d3.svg.diagonal()
    .source(function (d) {
    return {
        "x": d.source.x,
            "y": d.source.y
    };
})
    .target(function (d) {
    return {
        "x": d.target.x,
            "y": d.target.y
    };
});

var svg = d3.select("#body").append("svg")
    .attr("width", "100%")
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

root.x0 = height / 2;
root.y0 = 0;

function collapse(d) {
    if (d.children) {
        d._children = d.children;
        d._children.forEach(collapse);
        d.children = null;
    }
}

root.children.forEach(function (parent) {
    collapse(parent);
});

update(root);

function update(source) {

    // Compute the new tree layout.
    var nodes = tree.nodes(root),
        links = tree.links(nodes),
        position = [];

    nodes.forEach(function (d) {
        if (d.parent) {
            position[d.parent.id] = position[d.parent.id] || 1;
            d.position = position[d.parent.id]++;
            if (d.children && d.depth > 1) {
                d.children.forEach(function (entry) {
                    position[d.parent.id]++;
                });
            }
        }
        if (d.depth < 2) {
            d.y = d.depth * 60;
            if (d.parent) {
                columns = d.parent.children.length;
                //d.x = (d.position - 1 + columns / 12) * width / columns;
            } else {
                columns = d.children.length;
                //d.x = (width * (4 * columns - 1)) / (8 * columns);
                // d.x = width / 2;
            }
        } else {
            d.y = d.parent.y + d.position * 20;
            d.x = d.parent.x + 20;
        }
    });

    // Update the nodes…
    var node = svg.selectAll("g.node")
        .data(nodes, function (d) {
        return d.id || (d.id = ++i);
    });

    // Enter any new nodes at the parent's previous position.
    var nodeEnter = node.enter().append("g")
        .attr("class", "node")
        .attr("transform", function (d) {
        return "translate(" + source.x0 + "," + source.y0 + ")";
    })
        .on("click", click);

    nodeEnter.append("circle")
        .attr("r", 1e-6)
        .style("fill", function (d) {
        return d._children ? "lightsteelblue" : "#fff";
    });

    nodeEnter.append("text")
        .attr("x", function (d) {
        return 10;
    })
        .attr("dy", ".35em")
        .attr("text-anchor", function (d) {
        return "start";
    })
        .text(function (d) {
        //return d.name + " ("+d.x+","+d.y+")";
        return d.name;
    })
        .each(function (d) {
        d.width = this.getBBox().width;
    })
        .style("fill-opacity", 1e-6);

    // Transition nodes to their new position.
    var nodeUpdate = node.transition()
        .duration(duration)
        .attr("transform", function (d) {
        return "translate(" + d.x + "," + d.y + ")";
    });

    nodeUpdate.select("circle")
        .attr("r", 4.5)
        .style("fill", function (d) {
        return d._children ? "lightsteelblue" : "#fff";
    });

    nodeUpdate.select("text")
        .style("fill-opacity", 1);

    // Transition exiting nodes to the parent's new position.
    var nodeExit = node.exit().transition()
        .duration(duration)
        .attr("transform", function (d) {
        return "translate(" + source.x + "," + source.y + ")";
    })
        .remove();

    nodeExit.select("circle")
        .attr("r", 1e-6);

    nodeExit.select("text")
        .style("fill-opacity", 1e-6);

    // Update the links…
    var link = svg.selectAll("path.link")
        .data(links, function (d) {
        return d.target.id;
    });

    // Enter any new links at the parent's previous position.
    link.enter().insert("path", "g")
        .attr("class", "link")
        .attr("d", function (d) {
        var o = {
            x: source.x0,
            y: source.y0
        };
        return diagonal({
            source: o,
            target: o
        });
    });

    // Transition links to their new position.
    link.transition()
        .duration(duration)
        .attr("d", diagonal);

    // Transition exiting nodes to the parent's new position.
    link.exit().transition()
        .duration(duration)
        .attr("d", function (d) {
        var o = {
            x: source.x,
            y: source.y
        };
        return diagonal({
            source: o,
            target: o
        });
    })
        .remove();

    // Stash the old positions for transition.
    nodes.forEach(function (d) {
        d.x0 = d.x;
        d.y0 = d.y;
    });
}

// Toggle children on click.
function click(d) {
    if (d.children) {
        d._children = d.children;
        d.children = null;
    } else {
        d.children = d._children;
        d._children = null;
    }
    update(d);
}