@takram/three-atmosphere
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A Three.js and R3F implementation of Precomputed Atmospheric Scattering
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# @takram/three-atmosphere
[](https://www.npmjs.com/package/@takram/three-atmosphere) [](https://takram-design-engineering.github.io/three-geospatial/?path=/story/atmosphere-atmosphere--basic)
A Three.js and R3F (React Three Fiber) implementation of Eric Bruneton’s [Precomputed Atmospheric Scattering](https://ebruneton.github.io/precomputed_atmospheric_scattering/).
This library is part of a project to prototype the rendering aspect of a Web GIS engine. For more details on the background and current status of this project, please refer to the [main README](/README.md).
## Installation
```sh
npm install @takram/three-atmosphere
pnpm add @takram/three-atmosphere
yarn add @takram/three-atmosphere
```
Peer dependencies include `three` and `postprocessing`, as well as `@react-three/fiber`, `@react-three/postprocessing`, and `@react-three/drei` when using R3F.
```
three postprocessing
@react-three/fiber @react-three/postprocessing @react-three/drei
```
## Usage
### Deferred lighting
Suitable for large-scale scenes, but supports only Lambertian BRDF.
```tsx
import { useLoader } from '@react-three/fiber'
import { EffectComposer } from '@react-three/postprocessing'
import { PrecomputedTexturesLoader } from '@takram/three-atmosphere'
import {
AerialPerspective,
Atmosphere,
Sky
} from '@takram/three-atmosphere/r3f'
const Scene = () => {
const precomputedTextures = useLoader(PrecomputedTexturesLoader, '/assets')
return (
<Atmosphere
textures={precomputedTextures}
date={/* Date object or timestamp */}
>
<Sky />
<EffectComposer enableNormalPass>
<AerialPerspective skyIrradiance sunIrradiance />
</EffectComposer>
</Atmosphere>
)
}
```
→ [Storybook](https://takram-design-engineering.github.io/three-geospatial/?path=/story/atmosphere-3d-tiles-renderer-integration--manhattan)
→ [Storybook](https://takram-design-engineering.github.io/three-geospatial/?path=/story/atmosphere-3d-tiles-renderer-integration--fuji)
### Forward lighting
Compatible with built-in Three.js materials and shadows, but both direct and indirect irradiance are approximated only for small-scale scenes.
```tsx
import { useLoader } from '@react-three/fiber'
import { EffectComposer } from '@react-three/postprocessing'
import { PrecomputedTexturesLoader } from '@takram/three-atmosphere'
import {
AerialPerspective,
Atmosphere,
Sky,
SkyLight,
SunLight
} from '@takram/three-atmosphere/r3f'
const Scene = () => {
const precomputedTextures = useLoader(PrecomputedTexturesLoader, '/assets')
return (
<Atmosphere
textures={precomputedTextures}
date={/* Date object or timestamp */}
>
<Sky />
<group position={/* ECEF coordinate in meters */}>
<SkyLight />
<SunLight />
</group>
<EffectComposer>
<AerialPerspective />
</EffectComposer>
</Atmosphere>
)
}
```
→ [Storybook](https://takram-design-engineering.github.io/three-geospatial/?path=/story/atmosphere-atmosphere--vanilla)
### Transient update by date
```tsx
import { useFrame } from '@react-three/fiber'
import {
Atmosphere,
Sky,
type AtmosphereApi
} from '@takram/three-atmosphere/r3f'
import { useRef } from 'react'
const Scene = () => {
const atmosphereRef = useRef<AtmosphereApi>(null)
useFrame(() => {
atmosphereRef.current?.updateByDate(new Date())
})
return (
<Atmosphere ref={atmosphereRef}>
<Sky />
...
</Atmosphere>
)
}
```
### Non-suspending texture loading
```tsx
const Scene = () => (
// Provide a url instead of textures to load them asynchronously.
<Atmosphere textures='/assets'>
<Sky />
<EffectComposer>
<AerialPerspective />
</EffectComposer>
</Atmosphere>
)
```
### Vanilla Three.js
See the [story](/storybook/src/atmosphere/Atmosphere-Vanilla.tsx) for complete example.
```ts
const position = new Vector3(/* ECEF coordinate in meters */)
// SkyMaterial disables projection. Provide a plane that covers clip space.
const skyMaterial = new SkyMaterial()
const sky = new Mesh(new PlaneGeometry(2, 2), skyMaterial)
sky.frustumCulled = false
sky.position.copy(position)
scene.add(sky)
// SkyLightProbe computes sky irradiance of its position.
const skyLight = new SkyLightProbe()
skyLight.position.copy(position)
scene.add(skyLight)
// SunDirectionalLight computes sunlight transmittance to its target position.
const sunLight = new SunDirectionalLight()
sunLight.target.position.copy(position)
scene.add(sunLight)
scene.add(sunLight.target)
// Demonstrates forward lighting here. For deferred lighting, set sunIrradiance
// and skyIrradiance to true, remove SkyLightProbe and SunDirectionalLight, and
// provide a normal buffer to AerialPerspectiveEffect.
const aerialPerspective = new AerialPerspectiveEffect(camera)
// Use floating-point render buffer, as radiance/luminance is stored here.
const composer = new EffectComposer(renderer, {
frameBufferType: HalfFloatType
})
composer.addPass(new RenderPass(scene, camera))
composer.addPass(
new EffectPass(
camera,
aerialPerspective,
new ToneMappingEffect({ mode: ToneMappingMode.AGX })
)
)
const texturesLoader = new PrecomputedTexturesLoader()
texturesLoader.setTypeFromRenderer(renderer)
texturesLoader.load('/assets', textures => {
Object.assign(skyMaterial, textures)
sunLight.transmittanceTexture = textures.transmittanceTexture
skyLight.irradianceTexture = textures.irradianceTexture
Object.assign(aerialPerspective, textures)
})
const sunDirection = new Vector3()
const moonDirection = new Vector3()
function render(): void {
// Suppose `date` is updated elsewhere.
getSunDirectionECEF(date, sunDirection)
getMoonDirectionECEF(date, moonDirection)
skyMaterial.sunDirection.copy(sunDirection)
skyMaterial.moonDirection.copy(moonDirection)
sunLight.sunDirection.copy(sunDirection)
skyLight.sunDirection.copy(sunDirection)
aerialPerspective.sunDirection.copy(sunDirection)
sunLight.update()
skyLight.update()
composer.render()
}
```
## Limitations
- The reference frame is fixed to ECEF and cannot be configured, [#11](https://github.com/takram-design-engineering/three-geospatial/issues/11).
- The viewpoint is restricted to positions above the atmosphere’s inner sphere. It doesn’t render correctly underground, [#5](https://github.com/takram-design-engineering/three-geospatial/issues/5).
- The aerial perspective (specifically the inscatter term) includes a [workaround for the horizon artifact](https://github.com/ebruneton/precomputed_atmospheric_scattering/pull/32#issuecomment-480523982), but due to finite floating-point precision, this artifact cannot be removed completely.
- Volumetric light shaft is not implemented as it requires ray tracing or an additional depth pass from the sun. You may notice scattered light is not occluded by scene objects.
- Although you can generate custom precomputed textures, the implementation is effectively limited to Earth’s atmosphere. For rendering atmospheres of other planets, consider implementing Sébastien Hillaire’s [A Scalable and Production Ready Sky and Atmosphere Rendering Technique](https://sebh.github.io/publications/egsr2020.pdf).
- Currently developed using GLSL. It does not use node-based TSL yet, and WebGPU is not supported, but both are planned.
# API
The underlying concepts of these components and classes might be a bit complex. If you have any questions, feel free to ask in the Issues or Discussions.
**R3F components**
- [`Atmosphere`](#atmosphere)
- [`Sky`](#sky)
- [`Stars`](#stars)
- [`SkyLight`](#skylight)
- [`SunLight`](#sunlight)
- [`AerialPerspective`](#aerialperspective)
**Three.js**
- [`AtmosphereMaterialBase`](#atmospherematerialbase)
- [`SkyMaterial`](#skymaterial)
- [`StarsMaterial`](#starsmaterial)
- [`SkyLightProbe`](#skylightprobe)
- [`SunDirectionalLight`](#sundirectionallight)
- [`AerialPerspectiveEffect`](#aerialperspectiveeffect)
**Functions**
- [`getSunDirectionECEF`](#getsundirectionecef-getmoondirectionecef)
- [`getMoonDirectionECEF`](#getsundirectionecef-getmoondirectionecef)
- [`getECIToECEFRotationMatrix`](#getecitoecefrotationmatrix)
- [`getSunLightColor`](#getsunlightcolor)
## Atmosphere
Provides and synchronizes props of atmosphere components. It’s the recommended way to configure components unless you need finer control over properties of individual components.
→ [Source](/packages/atmosphere/src/r3f/Atmosphere.tsx)
```tsx
import { useFrame } from '@react-three/fiber'
import {
Atmosphere,
Sky,
useAtmosphereTextureProps,
type AtmosphereApi
} from '@takram/three-atmosphere/r3f'
import { useRef } from 'react'
const Scene = () => {
const atmosphereRef = useRef<AtmosphereApi>(null)
useFrame(() => {
// Computes sun direction, moon direction and ECI to ECEF rotation
// matrix by the date, then propagates them to descendant components via
// context.
atmosphereRef.current?.updateByDate(new Date())
})
// The choice of precomputed textures depends on whether single-precision
// float or half-float textures are supported. Some devices don't support
// single-precision textures, so this hook fallbacks to half-float textures
// when necessary.
const textureProps = useAtmosphereTextureProps('/assets')
return (
<Atmosphere ref={atmosphereRef} {...textureProps}>
<Sky />
...
</Atmosphere>
)
}
```
### Props
#### textures
```ts
textures: PrecomputedTextures | string = DEFAULT_PRECOMPUTED_TEXTURES_URL
```
The [precomputed textures](assets), or a URL to the directory containing them.
If left undefined, the textures will be loaded directly from GitHub.
#### ellipsoid
```ts
ellipsoid: Ellipsoid = Ellipsoid.WGS84
```
The ellipsoid model representing Earth.
#### correctAltitude
```ts
correctAltitude: boolean = true
```
Whether to adjust the atmosphere’s inner sphere to osculate (touch and share a tangent with) the ellipsoid.
The atmosphere is approximated as a sphere, with a radius between the ellipsoid’s major and minor axes. The difference can exceed 10,000 meters in worst cases, roughly equal to the cruising altitude of a passenger jet. This option compensates for this difference.
An example at an altitude of 2,000 meters and a latitude of 35°:
<!-- prettier-ignore -->
| `correctAltitude = false` | `correctAltitude = true` |
| :-: | :-: |
|  |  |
#### photometric
```ts
photometric: boolean = true
```
Whether to store luminance instead of radiance in render buffers.
<!-- prettier-ignore -->
| `photometric = false` | `photometric = true` |
| :-: | :-: |
|  |  |
#### date
```ts
date: number | Date = undefined
```
Specifies the date used to obtain the directions of the sun, moon, and ECI to ECEF rotation matrix.
The behavior when used together with the [`updateByDate`](#updatebydate) function is not defined.
### Ref
#### sunDirection, moonDirection
```ts
sunDirection: Vector3
moonDirection: Vector3
```
The normalized direction to the sun and moon in ECEF coordinates. This value is shared with descendant components and is overwritten by the [`date`](#date) prop or the [`updateByDate`](#updatebydate) function.
The default values are [0, 0, 0].
#### rotationMatrix
```ts
rotationMatrix: Matrix4
```
The rotation matrix for converting ECI to ECEF coordinates. This value is shared with descendant components and is overwritten by the [`date`](#date) prop or the [`updateByDate`](#updatebydate) function.
The default value is an identity matrix.
#### ellipsoidCenter, ellipsoidMatrix
```ts
ellipsoidCenter: Vector3
ellipsoidMatrix: Matrix4
```
The center coordinates and rotation matrix of the ellipsoid. Use these values to define a reference frame or, more commonly, to move the ellipsoid for working around the world space origin and adapting to Three.js’s Y-up coordinate system.
The default value of `ellipsoidCenter` is [0, 0, 0], and `ellipsoidMatrix` is an identity matrix.
```ts
import { type AtmosphereApi } from '@takram/three-atmosphere/r3f'
import { Ellipsoid } from '@takram/three-geospatial'
import { Vector3 } from 'three'
const position = new Vector3(/* ECEF coordinate in meters */)
const east = new Vector3()
const north = new Vector3()
const up = new Vector3()
declare const atmosphere: AtmosphereApi
// Offset the ellipsoid so that the world space origin locates at the
// position relative to the ellipsoid.
atmosphere.ellipsoidCenter.copy(position).multiplyScalar(-1)
// Rotate the ellipsoid around the world space origin so that the camera's
// orientation aligns with X: north, Y: up, Z: east, for example.
Ellipsoid.WGS84.getEastNorthUpVectors(position, east, north, up)
atmosphere.ellipsoidMatrix.makeBasis(north, up, east).invert()
```
See the [story](/storybook/src/atmosphere/Atmosphere-MovingEllipsoid.tsx) for complete example.
#### updateByDate
```ts
function updateByDate(date: number | Date): void
```
Updates the directions of the sun, moon, and the ECI to ECEF rotation matrix for the specified date. Use this function via the `ref` instead of the `date` prop if you want to update it smoothly.
The behavior when used together with the `date` prop is not defined.
## Sky
Displays the sky in a screen quad.
See [`SkyMaterial`](#skymaterial) for further details.
→ [Source](/packages/atmosphere/src/r3f/Sky.tsx)
```tsx
import { useLoader } from '@react-three/fiber'
import {
getMoonDirectionECEF,
getSunDirectionECEF,
PrecomputedTexturesLoader
} from '@takram/three-atmosphere'
import { Sky } from '@takram/three-atmosphere/r3f'
const sunDirection = getSunDirectionECEF(/* date */)
const moonDirection = getMoonDirectionECEF(/* date */)
const Scene = () => {
const precomputedTextures = useLoader(PrecomputedTexturesLoader, '/assets')
return (
<Sky
{...precomputedTextures}
sunDirection={sunDirection}
moonDirection={moonDirection}
/>
)
}
```
### Props
The parameters of [`AtmosphereMaterialBase`](#atmospherematerialbase) and [`SkyMaterial`](#skymaterial) are exposed as props.
## Stars
Represents the brightest stars as points at an infinite distance.
See [`StarsMaterial`](#starsmaterial) for further details.
→ [Source](/packages/atmosphere/src/r3f/Stars.tsx)
```tsx
import { useLoader } from '@react-three/fiber'
import {
getECIToECEFRotationMatrix,
getSunDirectionECEF,
PrecomputedTexturesLoader
} from '@takram/three-atmosphere'
import { Stars } from '@takram/three-atmosphere/r3f'
import { ArrayBufferLoader } from '@takram/three-geospatial'
const sunDirection = getSunDirectionECEF(/* date */)
const rotationMatrix = getECIToECEFRotationMatrix(/* date */)
const Scene = () => {
const precomputedTextures = useLoader(PrecomputedTexturesLoader, '/assets')
const starsData = useLoader(ArrayBufferLoader, '/assets/stars.bin')
return (
<Stars
{...precomputedTextures}
data={starsData}
sunDirection={sunDirection}
matrix={rotationMatrix}
/>
)
}
```
### Props
The parameters of [`AtmosphereMaterialBase`](#atmospherematerialbase) and [`StarsMaterial`](#starsmaterial) are also exposed as props.
#### data
```ts
data: ArrayBuffer | string = DEFAULT_STARS_DATA_URL
```
The data containing the position and magnitude of the stars, or a URL to it.
If left undefined, the data will be loaded directly from GitHub.
## SkyLight
A light probe for indirect sky irradiance.
See [`SkyLightProbe`](#skylightprobe) for further details.
→ [Source](/packages/atmosphere/src/r3f/SkyLight.tsx)
```tsx
import { useLoader } from '@react-three/fiber'
import {
getSunDirectionECEF,
IRRADIANCE_TEXTURE_HEIGHT,
IRRADIANCE_TEXTURE_WIDTH
} from '@takram/three-atmosphere'
import { SkyLight } from '@takram/three-atmosphere/r3f'
import {
createDataTextureLoaderClass,
parseFloat32Array
} from '@takram/three-geospatial'
import { Vector3 } from 'three'
const position = new Vector3(/* ECEF coordinate in meters */)
const sunDirection = getSunDirectionECEF(/* date */)
const Scene = () => {
const irradianceTexture = useLoader(
createDataTextureLoaderClass(parseFloat32Array, {
width: IRRADIANCE_TEXTURE_WIDTH,
height: IRRADIANCE_TEXTURE_HEIGHT
}),
'/assets/irradiance.bin'
)
return (
<SkyLight
irradianceTexture={irradianceTexture}
position={position}
sunDirection={sunDirection}
/>
)
}
```
### Props
The parameters of [`SkyLightProbe`](#skylightprobe) are exposed as props.
## SunLight
A directional light representing the sun.
See [`SunDirectionalLight`](#directionalsunlight) for further details.
→ [Source](/packages/atmosphere/src/r3f/SunLight.tsx)
```tsx
import { useLoader } from '@react-three/fiber'
import {
getSunDirectionECEF,
TRANSMITTANCE_TEXTURE_HEIGHT,
TRANSMITTANCE_TEXTURE_WIDTH
} from '@takram/three-atmosphere'
import { SunLight } from '@takram/three-atmosphere/r3f'
import {
createDataTextureLoaderClass,
parseFloat32Array
} from '@takram/three-geospatial'
import { Vector3 } from 'three'
const position = new Vector3(/* ECEF coordinate in meters */)
const sunDirection = getSunDirectionECEF(/* date */)
const Scene = () => {
const transmittanceTexture = useLoader(
createDataTextureLoaderClass(parseFloat32Array, {
width: TRANSMITTANCE_TEXTURE_WIDTH,
height: TRANSMITTANCE_TEXTURE_HEIGHT
}),
'/assets/transmittance.bin'
)
return (
<SunLight
transmittanceTexture={transmittanceTexture}
position={position}
sunDirection={sunDirection}
/>
)
}
```
### Props
The parameters of [`SunDirectionalLight`](#directionalsunlight) are exposed as props.
## AerialPerspective
A post-processing effect that renders atmospheric transparency and inscattered light.
See [`AerialPerspectiveEffect`](#aerialperspectiveeffect) for further details.
→ [Source](/packages/atmosphere/src/r3f/AerialPerspective.tsx)
```tsx
import { useLoader } from '@react-three/fiber'
import { EffectComposer } from '@react-three/postprocessing'
import {
getSunDirectionECEF,
PrecomputedTexturesLoader
} from '@takram/three-atmosphere'
import { AerialPerspective } from '@takram/three-atmosphere/r3f'
import { Vector3 } from 'three'
const sunDirection = getSunDirectionECEF(/* date */)
const Scene = () => {
const precomputedTextures = useLoader(PrecomputedTexturesLoader, '/assets')
return (
<EffectComposer>
<AerialPerspective {...precomputedTextures} sunDirection={sunDirection} />
</EffectComposer>
)
}
```
### Props
The parameters of [`AerialPerspectiveEffect`](#aerialperspectiveeffect) are exposed as props.
## AtmosphereMaterialBase
The base class of [`SkyMaterial`](#skymaterial) and [`StarsMaterial`](#starsmaterial).
→ [Source](/packages/atmosphere/src/AtmosphereMaterialBase.ts)
### Parameters
#### irradianceTexture, scatteringTexture, transmittanceTexture
```ts
irradianceTexture: DataTexture | null = null
scatteringTexture: Data3DTexture | null = null
transmittanceTexture: DataTexture | null = null
```
The [precomputed textures](assets).
#### ellipsoid
```ts
ellipsoid: Ellipsoid = Ellipsoid.WGS84
```
See [ellipsoid](#ellipsoid).
#### ellipsoidCenter, ellipsoidMatrix
```ts
ellipsoidCenter: Vector3
ellipsoidMatrix: Matrix4
```
See [ellipsoidCenter, ellipsoidMatrix](#ellipsoidcenter-ellipsoidmatrix).
#### correctAltitude
```ts
correctAltitude: boolean = true
```
See [correctAltitude](#correctaltitude).
#### photometric
```ts
photometric: boolean = true
```
See [photometric](#photometric).
#### sunDirection
```ts
sunDirection: Vector3 = new Vector3()
```
The normalized direction to the sun in ECEF coordinates.
#### sunAngularRadius
```ts
sunAngularRadius: number = 0.004675
```
The angular radius of the sun, in radians.
Increase this value if the sun flickers in a low-resolution environment map. Modifying this value does not affect the sky’s total radiance unless the sun is partially visible.
<!-- prettier-ignore -->
| `sunAngularRadius = 0.004675` | `sunAngularRadius = 0.1` |
| :-: | :-: |
|  |  |
## SkyMaterial
A material for displaying the sky. Apply this to a screen quad.
Despite its name, this material renders the atmosphere itself, along with the sun and moon. When viewed from within the atmosphere, it appears as the sky. From space, it represents Earth’s atmosphere with a flat ground.
→ [Source](/packages/atmosphere/src/SkyMaterial.ts)
```ts
const material = new SkyMaterial()
getSunDirectionECEF(/* date */, material.sunDirection)
const sky = new Mesh(new PlaneGeometry(2, 2), material)
sky.frustumCulled = false
scene.add(sky)
```
### Parameters
Extends [`AtmosphereMaterialBase`](#atmospherematerialbase).
#### sun, moon
```ts
sun: boolean = true
moon: boolean = true
```
Whether to display the sun and moon.
#### moonDirection
```ts
moonDirection: Vector3 = new Vector()
```
The normalized direction to the moon in ECEF coordinates.
#### moonAngularRadius
```ts
moonAngularRadius: number = 0.0045
```
The angular radius of the moon, in radians.
#### lunarRadianceScale
```ts
lunarRadianceScale: number = 1
```
A scaling factor to adjust the brightness of the moon.
<!-- prettier-ignore -->
| `lunarRadianceScale = 1` | `lunarRadianceScale = 5` |
| :-: | :-: |
|  |  |
#### groundAlbedo
```ts
groundAlbedo: Color = new Color()
```
The albedo of the ground. Defaults to 0.
## StarsMaterial
Represents the brightest stars as points at an infinite distance.
The provided data ([stars.bin](/packages/atmosphere/assets/stars.bin)) contains the J2000 ECI directions, magnitudes and black body chromaticities of the 9,096 stars listed in [Yale Bright Star Catalog version 5](http://tdc-www.harvard.edu/catalogs/bsc5.html).
→ [Source](/packages/atmosphere/src/StarsMaterial.ts)
```ts
const data: ArrayBuffer = /* Load stars.bin */
const material = new StarsMaterial({
irradianceTexture,
scatteringTexture,
transmittanceTexture
})
getSunDirectionECEF(/* date */, material.sunDirection)
const stars = new Points(new StarsGeometry(data), material)
stars.setRotationFromMatrix(getECIToECEFRotationMatrix(/* date */))
scene.add(stars)
```
### Parameters
Extends [`AtmosphereMaterialBase`](#atmospherematerialbase).
#### pointSize
```ts
pointSize: number = 1
```
The size of each star, in points.
#### radianceScale
```ts
radianceScale: number = 1
```
A scaling factor to adjust the brightness of the stars.
#### background
```ts
background: boolean = true
```
Whether to display the stars at an infinite distance, otherwise, they appear on a unit sphere.
## SkyLightProbe
A light probe for indirect sky irradiance.
It calculates spherical harmonics of sky irradiance at its position by sampling the precomputed irradiance texture on the CPU.
→ [Source](/packages/atmosphere/src/SkyLightProbe.ts)
```ts
const skyLight = new SkyLightProbe({ irradianceTexture })
skyLight.position.set(/* ECEF coordinate in meters */)
getSunDirectionECEF(/* date */, skyLight.sunDirection)
scene.add(skyLight)
skyLight.update()
```
### Parameters
Extends [`LightProbe`](https://threejs.org/docs/?q=lightprobe#api/en/lights/LightProbe)
#### irradianceTexture
```ts
irradianceTexture: DataTexture | null = null
```
The [precomputed irradiance texture](assets).
#### ellipsoid
```ts
ellipsoid: Ellipsoid = Ellipsoid.WGS84
```
See [ellipsoid](#ellipsoid).
#### ellipsoidCenter, ellipsoidMatrix
```ts
ellipsoidCenter: Vector3
ellipsoidMatrix: Matrix4
```
See [ellipsoidCenter, ellipsoidMatrix](#ellipsoidcenter-ellipsoidmatrix).
#### correctAltitude
```ts
correctAltitude: boolean = true
```
See [correctAltitude](#correctaltitude)
#### photometric
```ts
photometric: boolean = true
```
See [photometric](#photometric).
#### sunDirection
```ts
sunDirection: Vector3 = new Vector3()
```
See [sunDirection](#sundirection).
## SunDirectionalLight
A directional light representing the sun.
It calculates the sun’s radiance by sampling the precomputed transmittance texture on the CPU.
→ [Source](/packages/atmosphere/src/SunDirectionalLight.ts)
```ts
const sunLight = new SunDirectionalLight({ transmittanceTexture })
sunLight.target.position.set(/* ECEF coordinate in meters */)
getSunDirectionECEF(/* date */, sunLight.sunDirection)
scene.add(sunLight)
scene.add(sunLight.target)
sunLight.update()
```
### Parameters
Extends [`DirectionalLight`](https://threejs.org/docs/?q=DirectionalLight#api/en/lights/DirectionalLight)
#### transmittanceTexture
```ts
transmittanceTexture: DataTexture | null = null
```
The [precomputed transmittance texture](assets).
#### ellipsoid
```ts
ellipsoid: Ellipsoid = Ellipsoid.WGS84
```
See [ellipsoid](#ellipsoid).
#### ellipsoidCenter, ellipsoidMatrix
```ts
ellipsoidCenter: Vector3
ellipsoidMatrix: Matrix4
```
See [ellipsoidCenter, ellipsoidMatrix](#ellipsoidcenter-ellipsoidmatrix).
#### correctAltitude
```ts
correctAltitude: boolean = true
```
See [correctAltitude](#correctaltitude)
#### photometric
```ts
photometric: boolean = true
```
See [photometric](#photometric).
#### sunDirection
```ts
sunDirection: Vector3 = new Vector3()
```
See [sunDirection](#sundirection).
Note it's the direction to the sun, not that of light.
#### distance
```ts
distance: number = 1
```
The distance from the target. Adjust this value if shadows are enabled for the light, as it may need to cover the entire scene.
## AerialPerspectiveEffect
A post-processing effect that renders atmospheric transparency and inscattered light. It can optionally render sun and sky irradiance as deferred lighting.
This is for use with the [`postprocessing`](https://github.com/pmndrs/postprocessing)’s `EffectComposer` and is not compatible with the one in Three.js examples.
→ [Source](/packages/atmosphere/src/AerialPerspectiveEffect.ts)
```ts
const aerialPerspective = new AerialPerspectiveEffect(camera, {
irradianceTexture,
scatteringTexture,
transmittanceTexture
})
getSunDirectionECEF(/* date */, aerialPerspective.sunDirection)
const composer = new EffectComposer(renderer, {
frameBufferType: HalfFloatType
})
composer.addPass(new RenderPass(scene, camera))
composer.addPass(
new EffectPass(
camera,
aerialPerspective,
new ToneMappingEffect({ mode: ToneMappingMode.AGX })
)
)
```
### Parameters
Extends [`postprocessing`](https://github.com/pmndrs/postprocessing)’s [`Effect`](https://pmndrs.github.io/postprocessing/public/docs/class/src/effects/Effect.js~Effect.html).
#### normalBuffer
```ts
normalBuffer: Texture | null = null
```
The normal buffer used for deferred lighting. It is not required if both `sunIrradiance` and `skyIrradiance` are disabled.
`EffectComposer`’s default normal buffer lacks sufficient precision, causing banding in shaded areas. Using a floating-point normal buffer resolves this issue.
#### octEncodedNormal
```ts
octEncodedNormal: boolean = false
```
Indicates that the normal is oct-encoded and stored in the first two elements of the normal buffer texels.
#### reconstructNormal
```ts
reconstructNormal: boolean = false
```
Whether to reconstruct normals from depth buffer.
#### irradianceTexture, scatteringTexture, transmittanceTexture
```ts
irradianceTexture: DataTexture | null = null
scatteringTexture: Data3DTexture | null = null
transmittanceTexture: DataTexture | null = null
```
The [precomputed textures](assets).
#### ellipsoid
```ts
ellipsoid: Ellipsoid = Ellipsoid.WGS84
```
See [ellipsoid](#ellipsoid).
#### ellipsoidCenter, ellipsoidMatrix
```ts
ellipsoidCenter: Vector3
ellipsoidMatrix: Matrix4
```
See [ellipsoidCenter, ellipsoidMatrix](#ellipsoidcenter-ellipsoidmatrix).
#### correctAltitude
```ts
correctAltitude: boolean = true
```
See [correctAltitude](#correctaltitude)
#### correctGeometricError
```ts
correctGeometricError: boolean = true
```
These options corrects lighting artifacts caused by geometric errors in surface tiles. The Earth’s surface normals are gradually morphed to a true sphere.
Disable this option if your scene contains objects that penetrate the atmosphere or are located in space.
<!-- prettier-ignore -->
| `correctGeometricError = false` | `correctGeometricError = true` |
| :-: | :-: |
|  |  |
#### photometric
```ts
photometric: boolean = true
```
See [photometric](#photometric).
#### sunDirection
```ts
sunDirection: Vector3 = new Vector3()
```
See [sunDirection](#sundirection).
#### sunIrradiance, skyIrradiance
```ts
sunIrradiance: boolean = false
skyIrradiance: boolean = false
```
Whether to apply sun and sky irradiance as deferred lighting.
Enabling one without the other is physically incorrect and should only be done for demonstration purposes.
#### transmittance, inscatter
```ts
transmittance: boolean = true
inscatter: boolean = true
```
Whether to account for the atmospheric transmittance and inscattered light.
#### irradianceScale
```ts
irradianceScale: number = 1
```
This value adjusts the color buffer to reduce contrast.
Deferred lighting treats the color buffer as albedo, but textures like those in Google Photorealistic 3D Tiles have baked lighting and shadows, resulting in higher contrast. Adjusting this value helps make it less noticeable.
#### sky
```ts
sky: boolean = false
```
Whether to render the sky as a post-processing effect. Enabling this may reduce the total number of fragments needed to compute the sky radiance.
In this case, the `Sky` component is redundant and should be omitted.
#### sun, moon
```ts
sun: boolean = true
moon: boolean = true
```
See [sun, moon](#sun-moon).
#### moonDirection
```ts
moonDirection: Vector3 = new Vector()
```
See [moonDirection](#moondirection).
#### moonAngularRadius
```ts
moonAngularRadius: number = 0.0045
```
See [moonAngularRadius](#moonangularradius).
#### lunarRadianceScale
```ts
lunarRadianceScale: number = 1
```
See [lunarRadianceScale](#lunarradiancescale).
## Functions
### getSunDirectionECEF, getMoonDirectionECEF
```ts
function getSunDirectionECEF(date: number | Date, result?: Vector3): Vector3
function getMoonDirectionECEF(date: number | Date, result?: Vector3): Vector3
```
Obtains the direction to the sun and moon in ECEF coordinates for the specified UTC time. This internally uses [astronomy-engine](https://github.com/cosinekitty/astronomy) and it approximates UTC as being equivalent to UT1.
→ [Source](/packages/atmosphere/src/celestialDirections.ts)
### getECIToECEFRotationMatrix
```ts
function getECIToECEFRotationMatrix(
date: number | Date,
result?: Matrix4
): Matrix4
```
Obtains the rotation matrix to convert coordinates from J2000 ECI to ECEF. This internally uses [astronomy-engine](https://github.com/cosinekitty/astronomy) and it approximates UTC as being equivalent to UT1.
→ [Source](/packages/atmosphere/src/celestialDirections.ts)
### getSunLightColor
```ts
interface SunLightColorOptions {
ellipsoid?: Ellipsoid
correctAltitude?: boolean
photometric?: boolean
}
function getSunLightColor(
transmittanceTexture: DataTexture,
worldPosition: Vector3,
sunDirection: Vector3,
result?: Color,
options?: SunLightColorOptions
): Color
```
Calculates the radiance of sunlight observed from a given position by sampling the precomputed transmittance texture on the CPU.
→ [Source](/packages/atmosphere/src/getSunLightColor.ts)
# License
[MIT](LICENSE)