BodySet

Explained in Your first game, Rigid bodies.

class BodySet

import { BodySet } from '@driftengine/physics';

Constructor

`new`

constructor(capacity?: number)

Parameter	Type	Description
`capacity?`	`number`

Properties

Name	Type	Description
`count`	`number`
`posX`	`Float32Array`
`posY`	`Float32Array`
`posZ`	`Float32Array`
`rotX`	`Float32Array`
`rotY`	`Float32Array`
`rotZ`	`Float32Array`
`rotW`	`Float32Array`
`velX`	`Float32Array`
`velY`	`Float32Array`
`velZ`	`Float32Array`
`angX`	`Float32Array`
`angY`	`Float32Array`
`angZ`	`Float32Array`
`invMass`	`Float32Array`
`invInertia`	`Float32Array`	Body-frame inverse inertia, six symmetric terms per body: xx, yy, zz, xy, xz, yz.
`comX`	`Float32Array`	Centre of mass in body frame, which a shape built off-centre has.
`comY`	`Float32Array`
`comZ`	`Float32Array`
`friction`	`Float32Array`
`restitution`	`Float32Array`
`type`	`Uint8Array`
`flags`	`Uint8Array`
`sleepTicks`	`Uint16Array`
`layer`	`Uint32Array`
`mask`	`Uint32Array`
`shape`	`(ConvexShape \| undefined)[]`
`shapes`	`(readonly ConvexShape[] \| undefined)[]`	The parts of a compound body, or undefined where it has a single `shape`.

Methods

`add`

add(desc: BodyDesc): number

Parameter	Type	Description
`desc`	`BodyDesc`

`remove`

remove(index: number): number

Swap-remove. Returns the index that moved into index, or −1 if it was the last.

Parameter	Type	Description
`index`	`number`

`worldInverseInertia`

worldInverseInertia(index: number, out: Float32Array, at?: number): void

Fill out with the world-frame inverse inertia, six symmetric terms.

Parameter	Type	Description
`index`	`number`
`out`	`Float32Array`
`at?`	`number`

R · I⁻¹ · Rᵀ, a congruence, rather than a diagonalisation. Storing three principal moments would need an eigen decomposition, and Jacobi is iterative — a fixed sweep count would be deterministic but is one more thing to get exactly right for no gain. What this gives up is six floats per body instead of three and a congruence per substep. What would make it wrong is a measurement showing that congruence dominates the tick.