CompositeSurface

Explained in Your first game, Rigid bodies.

class CompositeSurface implements GroundSurface

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

Constructor

`new`

constructor(surfaces: readonly GroundSurface[])

Parameter	Type	Description
`surfaces`	`readonly GroundSurface[]`

Accessors

Name	Type	Description
`parts`get	`readonly GroundSurface[]`	The floors this is made of. More Exposed because "two of my floors are in the same column" is a question only the parts can answer, and it is one a consumer has to be able to ask. Two walkable surfaces overlapping with millimetres between them is invisible to every gameplay check — `sample` picks one and both readings look sane — while on screen the depth buffer cannot separate them and the pair flickers against each other as the camera turns. Composed, that information is gone.

Methods

`sample`

sample(x: number, z: number, out: SurfaceHit, atY?: number): boolean

Ask every part and keep the best answer.

Parameter	Type	Description
`x`	`number`
`z`	`number`
`out`	`SurfaceHit`
`atY?`	`number`

atY is what makes this correct rather than arbitrary. Without a reference height the only available rule is "highest wins", which teleports a character on the low line of a split up onto the high one the moment the two overlap.

`sampleBand`

sampleBand(x: number, z: number, out: SurfaceHit, loY: number, hiY: number): boolean

See GroundSurface.sampleBand: the highest floor any part puts in the band.

Parameter	Type	Description
`x`	`number`
`z`	`number`
`out`	`SurfaceHit`
`loY`	`number`
`hiY`	`number`

The one query where composing surfaces costs nothing in fidelity — a band is a filter, so asking every part and keeping the highest answer is the same answer a single surface holding all of them would give.