OcclusionBuffer

class OcclusionBuffer

import { OcclusionBuffer } from '@driftengine/core';

Constructor

`new`

constructor(options: OcclusionOptions)

Parameter	Type	Description
`options`	`OcclusionOptions`

Accessors

Name	Type	Description
`width`get	`number`
`height`get	`number`
`declared`get	`number`	How many occluders were declared this frame. Zero means every test answers "draw it".

Methods

`resize`

resize(options: OcclusionOptions): void

Rebuild the pyramid for a new size. Called when the drawing buffer's aspect changes.

Parameter	Type	Description
`options`	`OcclusionOptions`

Levels stop at 1x1: the coarsest level is one texel covering the whole frame, which is what a rectangle spanning the screen is tested against.

`begin`

begin(viewProj: ReadonlyMat4): void

Start a frame: clear to the far plane and take the matrix everything will be projected by.

Parameter	Type	Description
`viewProj`	`ReadonlyMat4`

`addOccluder`

addOccluder(min: ReadonlyArray<number> | Float32Array, max: ReadonlyArray<number> | Float32Array, model: ReadonlyMat4): void

Declare one occluder: a box in local space, placed by a model matrix.

Parameter	Type	Description
`min`	`ReadonlyArray<number> \| Float32Array`
`max`	`ReadonlyArray<number> \| Float32Array`
`model`	`ReadonlyMat4`

A box rather than the mesh, which is the same bargain a bounding sphere makes for the frustum: an occluder that is smaller than the thing it stands for is conservative, and a consumer knows the box that fits inside its wall. What would make it wrong is a consumer handing the mesh's own bounds for a shape with a hole in it, which would occlude through the hole — so the parameter is the box you may safely be hidden by, not the box you occupy.

`occluded`

occluded(bounds: Bounds, model: ReadonlyMat4): boolean

Whether a bounding sphere is entirely behind the declared occluders.

Parameter	Type	Description
`bounds`	`Bounds`
`model`	`ReadonlyMat4`

False whenever anything is uncertain, which is every case the arithmetic cannot settle: no occluders, a sphere crossing the near plane, a rectangle off the side of the frame. Drawing something hidden costs a draw call; culling something visible is a hole.

`occludedBox`

occludedBox(min: ArrayLike<number>, max: ArrayLike<number>): boolean

Whether a world-space box is entirely behind the declared occluders — the tighter question for something that is a box, where the cube around its sphere reaches far past it. A flat region is the case it exists for: a city block's sphere is half as deep underground as it is wide, nothing there occludes it, and the sphere test abstains for every block in the city. False whenever anything is uncertain, exactly as occluded.

Parameter	Type	Description
`min`	`ArrayLike<number>`
`max`	`ArrayLike<number>`