Mike Bostock

Force-directed graph layout using velocity Verlet integration.

d3-force

Wonderful! I wonder now how to make the nodes enter or exit the field from a constrained point around the circle to seek pending future relationships with some distribution of velocity.

Steve Ellis

Thanks. That’s basically how it works. The entering nodes are assigned phyllotaxis positions around the origin since their initial x and y properties are undefined.

https://github.com/d3/d3-force/blob/194dba9ed932670f2110c553da6b47a9069ea649/src/simulation.js#L66-L70

You can initialize the positions strictly to the center by replacing || {} with || {x: 0, y: 0}, but this doesn’t have much of an effect since when nodes are close the manyBody repulsive force is strongest, causing the nodes to fly apart at a rapid velocity. Finding an existing connected node by scanning the links array would probably be the most stable initial position.

Perhaps you could write a custom force that constrains the maximum speed of nodes? Like so: https://observablehq.com/d/1849551f209b16ed