eulerjs API / @eulerjs/marine / SpectralWaves

SpectralWaves

Defined in: packages/marine/src/waves/SpectralWaves.ts:116

An ocean of hundreds of thousands of waves, drawn from the JONSWAP spectrum of a wind sea and summed by inverse FFT (Tessendorf's "Simulating Ocean Water"): linear waves, sharpened at the crests by moving the surface's points sideways toward them.

The sea is a few square patches of different sizes, tiled, each holding its own band of wavelengths. The water mesh sums every wave of every patch on the GPU; the physics sums, on the CPU, the longest of them, those of the largest patches up to physicsResolution waves across: the waves a hull rides on, the same in both. Its FFT runs once a time step, and a height is then a few lookups in its grids.

Implements

• WaveSurface

Constructors

Constructor

new SpectralWaves(options?): SpectralWaves;

Defined in: packages/marine/src/waves/SpectralWaves.ts:160

Parameters

Parameter	Type
options?	SpectralWavesOptions

Returns

SpectralWaves

Properties

Property	Modifier	Type	Default value	Description	Defined in
gravity	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:122
gustPatches	readonly	number	undefined	Patches as small as this or smaller gust.	packages/marine/src/waves/SpectralWaves.ts:134
gusts	readonly	readonly object[]	undefined	The gusts' pattern: a few long sines, each (kx, kz, phase), summed.	packages/marine/src/waves/SpectralWaves.ts:132
inversionIterations	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:121
lastGridPoint	readonly	object	...	The undisplaced grid point the last heightAt or heightFrom found.	packages/marine/src/waves/SpectralWaves.ts:124
lastGridPoint.x	public	number	0	-	packages/marine/src/waves/SpectralWaves.ts:124
lastGridPoint.z	public	number	0	-	packages/marine/src/waves/SpectralWaves.ts:124
loopPeriod	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:120
patches	readonly	readonly WavePatch[]	undefined	-	packages/marine/src/waves/SpectralWaves.ts:117
physicsResolution	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:123
swell	readonly	readonly SwellWave[]	undefined	The swell's long waves, as their amplitude is for the sea's swellHeight now.	packages/marine/src/waves/SpectralWaves.ts:126
timeOffset	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:119
timeScale	readonly	number	undefined	-	packages/marine/src/waves/SpectralWaves.ts:118
version	public	number	0	Counts the changes setSea has made, for those drawing the waves to notice.	packages/marine/src/waves/SpectralWaves.ts:138
workerStatistics	readonly	object	...	Evaluations the worker had ready, and those it didn't and the main thread did instead.	packages/marine/src/waves/SpectralWaves.ts:136
workerStatistics.missed	public	number	0	-	packages/marine/src/waves/SpectralWaves.ts:136
workerStatistics.ready	public	number	0	-	packages/marine/src/waves/SpectralWaves.ts:136

Accessors

choppiness

Get Signature

get choppiness(): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:210

Returns

number

---

sea

Get Signature

get sea(): Readonly<SeaSettings>;

Defined in: packages/marine/src/waves/SpectralWaves.ts:206

The wind and waves the sea is made of now.

Returns

Readonly<SeaSettings>

---

significantWaveHeight

Get Signature

get significantWaveHeight(): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:237

The significant wave height, Hs: four times the standard deviation of the surface's height, about the mean height of the highest third of the waves, as a sea state is given in.

Returns

number

Methods

gustAt()

gustAt(gridX, gridZ): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:447

How much the gusting patches' waves are scaled by at the undisplaced grid point: one, plus the gustiness times the gusts' pattern, about as often above as below and seldom past two.

Parameters

Parameter	Type
gridX	number
gridZ	number

Returns

number

---

heightAt()

heightAt(
   worldX, 
   worldZ, 
   time
): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:295

Height of the surface directly above or below the world position (worldX, worldZ) at time.

Parameters

Parameter	Type
worldX	number
worldZ	number
time	number

Returns

number

Implementation of

WaveSurface.heightAt

---

heightFrom()

heightFrom(
   worldX, 
   worldZ, 
   time, 
   startGridX, 
   startGridZ, 
   iterations
): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:299

Like heightAt, but starts the search for the undisplaced grid point at (startGridX, startGridZ) and runs iterations steps; a good start needs one. The grid point found is left in lastGridPoint.

Parameters

Parameter	Type
worldX	number
worldZ	number
time	number
startGridX	number
startGridZ	number
iterations	number

Returns

number

Implementation of

WaveSurface.heightFrom

---

normalAt()

normalAt(
   worldX, 
   worldZ, 
   time, 
   target?
): Vector3;

Defined in: packages/marine/src/waves/SpectralWaves.ts:369

Upward unit normal of the surface at the world position (worldX, worldZ).

Parameters

Parameter	Type
worldX	number
worldZ	number
time	number
target?	Vector3

Returns

Vector3

Implementation of

WaveSurface.normalAt

---

phaseTime()

phaseTime(time): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:252

Time the waves are evaluated at for a given simulation time: scaled, offset, and wrapped round the loop period.

Parameters

Parameter	Type
time	number

Returns

number

---

prefetch()

prefetch(time): void;

Defined in: packages/marine/src/waves/SpectralWaves.ts:286

Asks the worker, if there is one, to evaluate the waves at time before they are needed.

Parameters

Parameter	Type
time	number

Returns

void

Implementation of

WaveSurface.prefetch

---

riseRate()

riseRate(
   gridX, 
   gridZ, 
   time
): number;

Defined in: packages/marine/src/waves/SpectralWaves.ts:322

How fast the surface point that started at grid position (gridX, gridZ) rises at time, in m/s: the water's own vertical velocity there, which is slower than the surface rises at a fixed place as a steep crest passes it. For floating bodies to move with the water. A surface without it, Buoyancy damps against the surface's rise at the place instead.

Parameters

Parameter	Type
gridX	number
gridZ	number
time	number

Returns

number

Implementation of

WaveSurface.riseRate

---

setSea()

setSea(changes): void;

Defined in: packages/marine/src/waves/SpectralWaves.ts:219

Changes the wind, or the waves' height or choppiness, while the sea runs. Each wave keeps the random draw it was made with, so the sea changes into the new one smoothly, swell by swell, rather than starting another; the physics, the worker and the water drawn all follow.

Parameters

Parameter	Type
changes	Partial<SeaSettings>

Returns

void

---

surfacePoint()

surfacePoint(
   gridX, 
   gridZ, 
   time, 
   target?
): Vector3;

Defined in: packages/marine/src/waves/SpectralWaves.ts:315

Where the surface point that started at grid position (gridX, gridZ) is at time, displaced sideways as well as up.

Parameters

Parameter	Type
gridX	number
gridZ	number
time	number
target?	Vector3

Returns

Vector3

Implementation of

WaveSurface.surfacePoint

---

swellPhasesAt()

swellPhasesAt(time, target): Float64Array;

Defined in: packages/marine/src/waves/SpectralWaves.ts:334

Each swell wave's phase at time, into target: its own, less how far it has turned, worked out in double precision and wrapped into a turn, so that it is as exact on the GPU.

Parameters

Parameter	Type
time	number
target	Float64Array

Returns

Float64Array

---

useWorker()

useWorker(port): void;

Defined in: packages/marine/src/waves/SpectralWaves.ts:264

Evaluates the physics' waves in a worker from now on, for the times prefetch asks for ahead (Buoyancy asks for the next few steps'); any other time, or one the worker hasn't finished, is still evaluated here. port is a Worker running @eulerjs/marine/spectral-worker.

Parameters

Parameter	Type
port	SpectralPort

Returns

void