`@ferret/physics-impact`

elastic and inelastic collisions, rest thresholds, sticking, impact events.

elastic and inelastic collisions. The kernel already bounces by the restitution of the two materials; this adds what a game dials per scope: the speed below which a bounce is a rest, a restitution scale, a loss of bounce at high impact speed, a perfectly inelastic mode (the bodies stick and move as one), and an event with the impulse and the energy lost.

values (each at world / level / zone / entity scope):

  threshold      closing speed (m/s) below which a bounce is a rest              (kernel default 0.2)
  scale          multiplies the restitution (0 = every hit is inelastic)         (1)
  falloff        { from, to, factor }: restitution falls linearly from 1x at `from` m/s to `factor` x at `to` m/s
  stick          true: two dynamic bodies that hit leave as one body              (false)
  minEventSpeed  smallest closing speed that raises `physics:impact`              (0.1)

Read the guide: how to use it →

4 exports · source in packages/physics-impact/src

Functions

impact function

function impact(): Capability

packages/physics-impact/src/index.ts:34

Interfaces

ImpactEvent interface

interface ImpactEvent

`a: Body`
`b: Body`
`entityA?: unknown`
`entityB?: unknown`
`point: Vec3`
`normal: Vec3`
`impulse: number`	normal impulse over the step, N·s
`speed: number`	closing speed, m/s
`restitution: number`	the restitution the hit was solved with (0 when below the threshold)
`energyLost: number`	kinetic energy turned into heat and deformation, J: ½·μ·(1 − e²)·v² with the reduced mass μ
`stuck: boolean`

packages/physics-impact/src/index.ts:16

ImpactFalloff interface

interface ImpactFalloff

values (each at world / level / zone / entity scope):

  threshold      closing speed (m/s) below which a bounce is a rest              (kernel default 0.2)
  scale          multiplies the restitution (0 = every hit is inelastic)         (1)
  falloff        { from, to, factor }: restitution falls linearly from 1x at `from` m/s to `factor` x at `to` m/s
  stick          true: two dynamic bodies that hit leave as one body              (false)
  minEventSpeed  smallest closing speed that raises `physics:impact`              (0.1)

`from: number`
`to: number`
`factor: number`

packages/physics-impact/src/index.ts:15

Constants

IMPACT_DEFAULTS const

const IMPACT_DEFAULTS: { threshold: number | undefined; scale: number; falloff: ImpactFalloff | undefined; stick: boolean; minEventSpeed: number; }

packages/physics-impact/src/index.ts:30