Minimal node interface for the simulation primitive. Matches d3-force's node shape exactly so d3-force's bundled forces work without translation.
Consumers extend this with arbitrary additional fields (id, label, etc.).
Optional
Pin x to this value when non-null. The integrator skips x/vx for the node.
Array index, written by initialize. Some forces (e.g. forceLink) rely on it.
initialize
Minimal node interface for the simulation primitive. Matches d3-force's node shape exactly so d3-force's bundled forces work without translation.
Consumers extend this with arbitrary additional fields (id, label, etc.).