Variable: atmosphere

const atmosphere: object

Defined in: modules/lighting/atmosphere/atmosphere.ts:36

Single-scattering Rayleigh/Mie sky and aerial perspective. Distances are metres. Includes a spherical planet's solar occlusion, without multiple scattering or ozone.

Type Declaration

defaultUniforms

readonly defaultUniforms: AtmosphereUniforms = DEFAULT_UNIFORMS

fs

readonly fs: "\nlayout(std140) uniform atmosphereUniforms {\n float enabled;\n vec3 sunDirection;\n float sunIntensity;\n float haze;\n float rayleigh;\n float planetRadius;\n float exposure;\n vec3 groundColor;\n} atmosphere;\nstruct AtmosphereSample {\n vec3 radiance;\n vec3 transmittance;\n};\n\nvec2 atmosphere_intersectSphere(vec3 origin, vec3 direction, float radius) {\n float projected = dot(origin, direction);\n float discriminant = projected * projected - (dot(origin.xy, origin.xy) + (origin.z - radius) * (origin.z + radius));\n if (discriminant < 0.0) return vec2(-1.0);\n float root = sqrt(discriminant);\n return vec2(-projected - root, -projected + root);\n}\nvec2 atmosphere_getDensity(vec3 position) {\n float height = max(length(position) - atmosphere.planetRadius, 0.0);\n return exp(-vec2(height / 8000.0, height / 1200.0));\n}\nAtmosphereSample atmosphere_getScattering(vec3 camera, vec3 direction, float distanceLimit) {\n AtmosphereSample result;\n result.radiance = vec3(0.0);\n result.transmittance = vec3(1.0);\n if (atmosphere.enabled < 0.5 || distanceLimit <= 0.0) return result;\n vec3 origin = vec3(camera.xy, atmosphere.planetRadius + max(camera.z, 1.0));\n vec2 shell = atmosphere_intersectSphere(origin, direction, atmosphere.planetRadius + 100000.0);\n float start = max(shell.x, 0.0);\n float end = min(shell.y, distanceLimit);\n vec2 ground = atmosphere_intersectSphere(origin, direction, atmosphere.planetRadius);\n if (ground.x > 0.0) end = min(end, ground.x);\n if (end <= start) return result;\n vec3 sunlight = normalize(atmosphere.sunDirection);\n vec3 rayleigh = vec3(0.0000058, 0.0000135, 0.0000331) * max(atmosphere.rayleigh, 0.0);\n vec3 mie = vec3(0.000021) * max(atmosphere.haze, 0.0);\n float cosine = dot(direction, sunlight);\n float rayleighPhase = 0.0596831 * (1.0 + cosine * cosine);\n float asymmetry = 0.76;\n float miePhase = (1.0 - asymmetry * asymmetry) / (12.566371 * pow(max(1.0 + asymmetry * asymmetry - 2.0 * asymmetry * cosine, 0.001), 1.5));\n float stepLength = (end - start) / 12.0;\n vec2 opticalDepth = vec2(0.0);\n vec3 radiance = vec3(0.0);\n for (int sampleIndex = 0; sampleIndex < 12; sampleIndex++) {\n vec3 position = origin + direction * (start + (float(sampleIndex) + 0.5) * stepLength);\n vec2 density = atmosphere_getDensity(position);\n vec2 centerDepth = opticalDepth + density * stepLength * 0.5;\n opticalDepth += density * stepLength;\n vec2 solarGround = atmosphere_intersectSphere(position, sunlight, atmosphere.planetRadius);\n if (solarGround.x > 0.0) continue;\n float solarDistance = max(atmosphere_intersectSphere(position, sunlight, atmosphere.planetRadius + 100000.0).y, 0.0);\n float solarStep = solarDistance / 4.0;\n vec2 solarDepth = vec2(0.0);\n for (int solarIndex = 0; solarIndex < 4; solarIndex++) {\n solarDepth += atmosphere_getDensity(position + sunlight * ((float(solarIndex) + 0.5) * solarStep)) * solarStep;\n }\n vec3 attenuation = exp(-rayleigh * (centerDepth.x + solarDepth.x) - mie * (centerDepth.y + solarDepth.y));\n radiance += attenuation * (rayleigh * density.x * rayleighPhase + mie * density.y * miePhase) * stepLength;\n }\n result.radiance = radiance * max(atmosphere.sunIntensity, 0.0);\n result.transmittance = exp(-rayleigh * opticalDepth.x - mie * opticalDepth.y);\n return result;\n}\nvec3 atmosphere_getSkyColor(vec3 camera, vec3 direction) {\n if (atmosphere.enabled < 0.5) return vec3(0.0);\n AtmosphereSample scatteringSample = atmosphere_getScattering(camera, normalize(direction), 1000000.0);\n vec3 origin = vec3(camera.xy, atmosphere.planetRadius + max(camera.z, 1.0));\n vec3 sunlight = normalize(atmosphere.sunDirection);\n float groundDistance = atmosphere_intersectSphere(origin, normalize(direction), atmosphere.planetRadius).x;\n if (groundDistance > 0.0 && sunlight.z > 0.0) {\n // Approximate direct irradiance at the ground boundary, attenuated on its way to the eye.\n float elevation = max(sunlight.z, 0.02);\n vec3 extinction = vec3(0.0000058, 0.0000135, 0.0000331) * max(atmosphere.rayleigh, 0.0) * 8000.0\n + vec3(0.000021) * max(atmosphere.haze, 0.0) * 1200.0;\n scatteringSample.radiance += atmosphere.groundColor * atmosphere.sunIntensity * sunlight.z / 3.141593\n * exp(-extinction / elevation) * scatteringSample.transmittance;\n }\n return vec3(1.0) - exp(-scatteringSample.radiance * atmosphere.exposure);\n}\nvec4 atmosphere_getColor(vec4 color, vec3 position, vec3 camera) {\n vec3 difference = position - camera;\n float distance = length(difference);\n if (distance < 0.001 || atmosphere.enabled < 0.5) return color;\n AtmosphereSample scatteringSample = atmosphere_getScattering(camera, difference / distance, distance);\n vec3 scattering = vec3(1.0) - exp(-scatteringSample.radiance * atmosphere.exposure);\n return vec4(color.rgb * scatteringSample.transmittance + scattering, color.a);\n}\n"

name

readonly name: "atmosphere" = 'atmosphere'

source

readonly source: "\nstruct atmosphereUniforms {\n enabled: f32,\n sunDirection: vec3f,\n sunIntensity: f32,\n haze: f32,\n rayleigh: f32,\n planetRadius: f32,\n exposure: f32,\n groundColor: vec3f,\n};\n@group(3) @binding(auto) var<uniform> atmosphere: atmosphereUniforms;\nstruct AtmosphereSample { radiance: vec3f,\n transmittance: vec3f };\n\nfn atmosphere_intersectSphere(origin: vec3f,\n direction: vec3f,\n radius: f32) -> vec2f {\n var projected: f32 = dot(origin, direction);\n var discriminant: f32 = projected * projected - (dot(origin.xy, origin.xy) + (origin.z - radius) * (origin.z + radius));\n if (discriminant < 0.0) { return vec2f(-1.0); }\n var root: f32 = sqrt(discriminant);\n return vec2f(-projected - root, -projected + root);\n}\nfn atmosphere_getDensity(position: vec3f) -> vec2f {\n var height: f32 = max(length(position) - atmosphere.planetRadius, 0.0);\n return exp(-vec2f(height / 8000.0, height / 1200.0));\n}\nfn atmosphere_getScattering(camera: vec3f,\n direction: vec3f,\n distanceLimit: f32) -> AtmosphereSample {\n var result: AtmosphereSample;\n result.radiance = vec3f(0.0);\n result.transmittance = vec3f(1.0);\n if (atmosphere.enabled < 0.5 || distanceLimit <= 0.0) { return result; }\n var origin: vec3f = vec3f(camera.xy, atmosphere.planetRadius + max(camera.z, 1.0));\n var shell: vec2f = atmosphere_intersectSphere(origin, direction, atmosphere.planetRadius + 100000.0);\n var start: f32 = max(shell.x, 0.0);\n var end: f32 = min(shell.y, distanceLimit);\n var ground: vec2f = atmosphere_intersectSphere(origin, direction, atmosphere.planetRadius);\n if (ground.x > 0.0) { end = min(end, ground.x); }\n if (end <= start) { return result; }\n var sunlight: vec3f = normalize(atmosphere.sunDirection);\n var rayleigh: vec3f = vec3f(0.0000058, 0.0000135, 0.0000331) * max(atmosphere.rayleigh, 0.0);\n var mie: vec3f = vec3f(0.000021) * max(atmosphere.haze, 0.0);\n var cosine: f32 = dot(direction, sunlight);\n var rayleighPhase: f32 = 0.0596831 * (1.0 + cosine * cosine);\n var asymmetry: f32 = 0.76;\n var miePhase: f32 = (1.0 - asymmetry * asymmetry) / (12.566371 * pow(max(1.0 + asymmetry * asymmetry - 2.0 * asymmetry * cosine, 0.001), 1.5));\n var stepLength: f32 = (end - start) / 12.0;\n var opticalDepth: vec2f = vec2f(0.0);\n var radiance: vec3f = vec3f(0.0);\n for (var sampleIndex: i32 = 0; sampleIndex < 12; sampleIndex++) {\n var position: vec3f = origin + direction * (start + (f32(sampleIndex) + 0.5) * stepLength);\n var density: vec2f = atmosphere_getDensity(position);\n var centerDepth: vec2f = opticalDepth + density * stepLength * 0.5;\n opticalDepth += density * stepLength;\n var solarGround: vec2f = atmosphere_intersectSphere(position, sunlight, atmosphere.planetRadius);\n if (solarGround.x > 0.0) { continue; }\n var solarDistance: f32 = max(atmosphere_intersectSphere(position, sunlight, atmosphere.planetRadius + 100000.0).y, 0.0);\n var solarStep: f32 = solarDistance / 4.0;\n var solarDepth: vec2f = vec2f(0.0);\n for (var solarIndex: i32 = 0; solarIndex < 4; solarIndex++) {\n solarDepth += atmosphere_getDensity(position + sunlight * ((f32(solarIndex) + 0.5) * solarStep)) * solarStep;\n }\n var attenuation: vec3f = exp(-rayleigh * (centerDepth.x + solarDepth.x) - mie * (centerDepth.y + solarDepth.y));\n radiance += attenuation * (rayleigh * density.x * rayleighPhase + mie * density.y * miePhase) * stepLength;\n }\n result.radiance = radiance * max(atmosphere.sunIntensity, 0.0);\n result.transmittance = exp(-rayleigh * opticalDepth.x - mie * opticalDepth.y);\n return result;\n}\nfn atmosphere_getSkyColor(camera: vec3f,\n direction: vec3f) -> vec3f {\n if (atmosphere.enabled < 0.5) { return vec3f(0.0); }\n var scatteringSample: AtmosphereSample = atmosphere_getScattering(camera, normalize(direction), 1000000.0);\n let origin = vec3f(camera.xy, atmosphere.planetRadius + max(camera.z, 1.0));\n let sunlight = normalize(atmosphere.sunDirection);\n let groundDistance = atmosphere_intersectSphere(origin, normalize(direction), atmosphere.planetRadius).x;\n if (groundDistance > 0.0 && sunlight.z > 0.0) {\n // Approximate direct irradiance at the ground boundary, attenuated on its way to the eye.\n let elevation = max(sunlight.z, 0.02);\n let extinction = vec3f(0.0000058, 0.0000135, 0.0000331) * max(atmosphere.rayleigh, 0.0) * 8000.0\n + vec3f(0.000021) * max(atmosphere.haze, 0.0) * 1200.0;\n scatteringSample.radiance += atmosphere.groundColor * atmosphere.sunIntensity * sunlight.z / 3.141593\n * exp(-extinction / elevation) * scatteringSample.transmittance;\n }\n return vec3f(1.0) - exp(-scatteringSample.radiance * atmosphere.exposure);\n}\nfn atmosphere_getColor(color: vec4f,\n position: vec3f,\n camera: vec3f) -> vec4f {\n var difference: vec3f = position - camera;\n var distance: f32 = length(difference);\n if (distance < 0.001 || atmosphere.enabled < 0.5) { return color; }\n var scatteringSample: AtmosphereSample = atmosphere_getScattering(camera, difference / distance, distance);\n var scattering: vec3f = vec3f(1.0) - exp(-scatteringSample.radiance * atmosphere.exposure);\n return vec4f(color.rgb * scatteringSample.transmittance + scattering, color.a);\n}\n"

uniformTypes

readonly uniformTypes: object

uniformTypes.enabled

readonly enabled: "f32" = 'f32'

uniformTypes.exposure

readonly exposure: "f32" = 'f32'

uniformTypes.groundColor

readonly groundColor: "vec3<f32>" = 'vec3<f32>'

uniformTypes.haze

readonly haze: "f32" = 'f32'

uniformTypes.planetRadius

readonly planetRadius: "f32" = 'f32'

uniformTypes.rayleigh

readonly rayleigh: "f32" = 'f32'

uniformTypes.sunDirection

readonly sunDirection: "vec3<f32>" = 'vec3<f32>'

uniformTypes.sunIntensity

readonly sunIntensity: "f32" = 'f32'

getUniforms()

readonly getUniforms(props?, previousUniforms?): object

Parameters

props?

Partial<Partial<AtmosphereUniforms>> = {}

previousUniforms?

AtmosphereUniforms | undefined

Returns

enabled

enabled: number

exposure

exposure: number

groundColor

groundColor: [number, number, number]

Diffuse ground boundary beneath the horizon, in linear RGB.

haze

haze: number

Aerosol and molecular scattering multipliers.

planetRadius

planetRadius: number

Planet radius in metres. Positions use a local tangent frame, with z = altitude.

rayleigh

rayleigh: number

sunDirection

sunDirection: [number, number, number]

Direction toward the sun in a local east/north/up frame; must be nonzero.

sunIntensity

sunIntensity: number