forcefield-wasm

wasm-bindgen build of forcefield, a Rust port of d3-force with tick-for-tick parity against the JS reference. Positions, velocities and pins are Float64Array views onto wasm memory: no per-tick copy.

import init, { Simulation } from 'forcefield-wasm'
await init()
const sim = Simulation.fromPositions(Float64Array.of(0, 0, 10, 3, NaN, NaN)) // NaN = spiral init
sim.forceManyBody('charge', [-30], 0.9, 1, Infinity)          // length-1 array = constant
sim.forceLink('link', Uint32Array.of(0, 1), Uint32Array.of(1, 2), [30], [], 1)
sim.tick(1)
const pos = sim.positions()   // [x0, y0, x1, y1, …] view; re-fetch after any non-tick call

Custom JS forces: sim.forceCustom(name, (alpha, pos, vel, fix) => …), called each tick with fresh views; do not call the simulation from inside it. For cytoscape.js use cytoscape-forcefield.

Beyond d3, there are two native additions:

• sim.forcePairOrder(name, lefts, rights, gap, strength) keeps index pairs apart along x;
• sim.setCooling(adaptive, alphaDecay, movementThreshold) switches between d3's fixed decay and movement-gated cooling (isAdaptive() reads which is on). Full API in forcefield.d.ts. BSD-3-Clause; derivative of d3-force (Mike Bostock).