block by GerHobbelt 3669455

d3.js: using layout.force to plot tree graphs (where nodes may have multiple parents) - Part 1: pure tree

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Experiment ……

Constructing a tree view using the d3.layout.force

This is prelude to constructing tree-like graphs using the force layout.

Lessons learned

Implementation Nodes, er, Notes

All constraints are applied in the force.on(“tick”) event handler.

We also implement drag behaviour, which, like any other use of node.fixed, will add a .px/.py coordinate pair for each node under the hood. To prevent any ‘Crazy Ivan jumping’ of nodes and other unexpected behaviour, we must ensure that .x/.y and .px/.py match once we are done in the force.tick handler, otherwise the next mouseenter/drag will behave very oddly. It is always a good rule to set both .px/.py and .x/.y when you update force nodes’ x/y coordinates.

This example is derived off the D3 example examples/force/force-collapsible.html.

The code requires a D3 version which includes (pull request #803](