Physics

Phase-6 adoption (manim-physics-inspired). Analytic fields/waves are dependency-free; rigid-body uses a built-in engine by default (pluggable).

Electromagnetic fields (analytic)

import { ElectricField, MagneticField } from "ecmanim";
scene.add(new ElectricField([
  { position: [-2, 0, 0], magnitude: 1 },   // + charge
  { position: [2, 0, 0], magnitude: -1 },    // − charge
]));
scene.add(new MagneticField([{ position: [0, 0, 0], magnitude: 1 }])); // out-of-plane current

electricFieldFunc(charges) / magneticFieldFunc(currents) return the raw field functions (Coulomb; B = I·(ẑ×r)/|r|²) for use anywhere a (p) → vector is wanted.

Waves

import { LinearWave, StandingWave } from "ecmanim";
scene.add(new LinearWave({ amplitude: 1, wavelength: 3, frequency: 1 }));   // y = A·sin(kx − ωt)
scene.add(new StandingWave({ amplitude: 1, wavelength: 4 }));               // y = A·sin(kx)·cos(ωt)

The wave advances automatically (an updater increments its time). setTime(t) sets it explicitly.

Rigid-body

import { physics, Pendulum } from "ecmanim";
const engine = physics(scene, { gravity: [0, -9.8, 0], floor: -3, restitution: 0.6 });
engine.addBody(ball, { velocity: [1, 0, 0] });   // falls + bounces off the floor
scene.add(new Pendulum({ length: 2, initialAngle: 0.9 })); // ODE-integrated each frame

The default SimpleEngine (semi-implicit Euler + gravity + floor collision) is dependency-free and stepped per frame. Pendulum integrates θ'' = −(g/L)·sinθ directly (no engine needed).

SimpleEngine limitations — know what you’re getting:

• Rotation is kinematic only: addBody(mob, { angularVelocity: 2 }) spins a body at a constant rate about its center, but collisions never impart or change spin (no friction impulses, no moment of inertia).
• The only collision is the floor plane (with restitution). There is no body–body collision, no walls, no arbitrary shapes, no constraints/joints.
• Integration is plain semi-implicit Euler — fine for demos, not for stacked or resting-contact scenes (objects will jitter or sink).

For anything beyond “things fall and bounce”, bring a real engine — the interface is pluggable (same step(dt) contract): planck.js (pure-JS Box2D — recommended, no WASM) or @dimforge/rapier2d (WASM) when cross-machine bit-exact determinism matters. Note that neither adapter ships in the box yet; you implement PhysicsEngineLike around the engine of your choice.