Accueil / npm / three@0.186.1 / examples / jsm / objects / Sky.js
Sky.js
import {
BackSide,
BoxGeometry,
Mesh,
ShaderMaterial,
UniformsUtils,
Vector3
} from 'three';
/**
* Represents a skydome for scene backgrounds. Based on [A Practical Analytic Model for Daylight](https://www.researchgate.net/publication/220720443_A_Practical_Analytic_Model_for_Daylight)
* aka The Preetham Model, the de facto standard for analytical skydomes.
*
* Note that this class can only be used with {@link WebGLRenderer}.
* When using {@link WebGPURenderer}, use {@link SkyMesh}.
*
* More references:
*
* - {@link http://simonwallner.at/project/atmospheric-scattering/}
* - {@link http://blenderartists.org/forum/showthread.php?245954-preethams-sky-impementation-HDR}
*
*
* ```js
* const sky = new Sky();
* sky.scale.setScalar( 10000 );
* scene.add( sky );
* ```
*
* It can be useful to hide the sun disc when generating an environment map to avoid artifacts
*
* ```js
* // disable before rendering environment map
* sky.material.uniforms.showSunDisc.value = false;
* // ...
* // re-enable before scene sky box rendering
* sky.material.uniforms.showSunDisc.value = true;
* ```
*
* @augments Mesh
* @three_import import { Sky } from 'three/addons/objects/Sky.js';
*/
class Sky extends Mesh {
/**
* Constructs a new skydome.
*/
constructor() {
const shader = Sky.SkyShader;
const material = new ShaderMaterial( {
name: shader.name,
uniforms: UniformsUtils.clone( shader.uniforms ),
vertexShader: shader.vertexShader,
fragmentShader: shader.fragmentShader,
side: BackSide,
depthWrite: false
} );
super( new BoxGeometry( 1, 1, 1 ), material );
/**
* This flag can be used for type testing.
*
* @type {boolean}
* @readonly
* @default true
*/
this.isSky = true;
}
}
Sky.SkyShader = {
name: 'SkyShader',
uniforms: {
'turbidity': { value: 2 },
'rayleigh': { value: 1 },
'mieCoefficient': { value: 0.005 },
'mieDirectionalG': { value: 0.8 },
'sunPosition': { value: new Vector3() },
'cloudScale': { value: 0.0002 },
'cloudSpeed': { value: 0.00002 },
'cloudCoverage': { value: 0.4 },
'cloudDensity': { value: 0.4 },
'cloudElevation': { value: 0.5 },
'showSunDisc': { value: 1 },
'time': { value: 0.0 }
},
vertexShader: /* glsl */`
uniform vec3 sunPosition;
uniform float rayleigh;
uniform float turbidity;
uniform float mieCoefficient;
varying vec3 vWorldPosition;
varying vec3 vSunDirection;
varying float vSunfade;
varying vec3 vBetaR;
varying vec3 vBetaM;
varying float vSunE;
// constants for atmospheric scattering
const float e = 2.71828182845904523536028747135266249775724709369995957;
const float pi = 3.141592653589793238462643383279502884197169;
// wavelength of used primaries, according to preetham
const vec3 lambda = vec3( 680E-9, 550E-9, 450E-9 );
// this pre-calculation replaces older TotalRayleigh(vec3 lambda) function:
// (8.0 * pow(pi, 3.0) * pow(pow(n, 2.0) - 1.0, 2.0) * (6.0 + 3.0 * pn)) / (3.0 * N * pow(lambda, vec3(4.0)) * (6.0 - 7.0 * pn))
const vec3 totalRayleigh = vec3( 5.804542996261093E-6, 1.3562911419845635E-5, 3.0265902468824876E-5 );
// mie stuff
// K coefficient for the primaries
const float v = 4.0;
const vec3 K = vec3( 0.686, 0.678, 0.666 );
// MieConst = pi * pow( ( 2.0 * pi ) / lambda, vec3( v - 2.0 ) ) * K
const vec3 MieConst = vec3( 1.8399918514433978E14, 2.7798023919660528E14, 4.0790479543861094E14 );
// earth shadow hack
// cutoffAngle = pi / 1.95;
const float cutoffAngle = 1.6110731556870734;
const float steepness = 1.5;
const float EE = 1000.0;
float sunIntensity( float zenithAngleCos ) {
zenithAngleCos = clamp( zenithAngleCos, -1.0, 1.0 );
return EE * max( 0.0, 1.0 - pow( e, -( ( cutoffAngle - acos( zenithAngleCos ) ) / steepness ) ) );
}
vec3 totalMie( float T ) {
float c = ( 0.2 * T ) * 10E-18;
return 0.434 * c * MieConst;
}
void main() {
vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
vWorldPosition = worldPosition.xyz;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
gl_Position.z = gl_Position.w; // set z to camera.far
vSunDirection = normalize( sunPosition );
vSunE = sunIntensity( vSunDirection.y );
vSunfade = 1.0 - clamp( 1.0 - exp( ( sunPosition.y / 450000.0 ) ), 0.0, 1.0 );
float rayleighCoefficient = rayleigh - ( 1.0 * ( 1.0 - vSunfade ) );
// extinction (absorption + out scattering)
// rayleigh coefficients
vBetaR = totalRayleigh * rayleighCoefficient;
// mie coefficients
vBetaM = totalMie( turbidity ) * mieCoefficient;
}`,
fragmentShader: /* glsl */`
varying vec3 vWorldPosition;
varying vec3 vSunDirection;
varying vec3 vBetaR;
varying vec3 vBetaM;
varying float vSunE;
uniform float mieDirectionalG;
uniform float cloudScale;
uniform float cloudSpeed;
uniform float cloudCoverage;
uniform float cloudDensity;
uniform float cloudElevation;
uniform float showSunDisc;
uniform float time;
// gradient at a lattice corner; sinless hash so every GPU produces the same clouds
vec2 gradient( vec2 i ) {
vec3 p = fract( i.xyx * vec3( 0.1031, 0.1030, 0.0973 ) );
p += dot( p, p.yzx + 33.33 );
return fract( ( p.xx + p.yz ) * p.zy ) * 2.0 - 1.0;
}
// 2D gradient noise: isotropic lobes like Perlin at value-noise cost
float noise( vec2 p ) {
vec2 i = floor( p );
vec2 f = fract( p );
vec2 u = f * f * f * ( f * ( f * 6.0 - 15.0 ) + 10.0 ); // quintic fade
float a = dot( gradient( i ), f );
float b = dot( gradient( i + vec2( 1.0, 0.0 ) ), f - vec2( 1.0, 0.0 ) );
float c = dot( gradient( i + vec2( 0.0, 1.0 ) ), f - vec2( 0.0, 1.0 ) );
float d = dot( gradient( i + vec2( 1.0, 1.0 ) ), f - vec2( 1.0, 1.0 ) );
return mix( mix( a, b, u.x ), mix( c, d, u.x ), u.y ) * 1.6; // ~[-1,1]
}
// fbm; per-octave drift makes clouds billow instead of scrolling as a rigid stamp
float fbm( vec2 p, float drift ) {
float result = 0.0;
float amplitude = 1.0;
for ( int i = 0; i < 4; i ++ ) {
result += amplitude * noise( p );
amplitude *= 0.5;
p = p * 2.0 + drift;
}
return result;
}
// constants for atmospheric scattering
const float pi = 3.141592653589793238462643383279502884197169;
const float n = 1.0003; // refractive index of air
const float N = 2.545E25; // number of molecules per unit volume for air at 288.15K and 1013mb (sea level -45 celsius)
// optical length at zenith for molecules
const float rayleighZenithLength = 8.4E3;
const float mieZenithLength = 1.25E3;
// 66 arc seconds -> degrees, and the cosine of that
const float sunAngularDiameterCos = 0.999956676946448443553574619906976478926848692873900859324;
// 3.0 / ( 16.0 * pi )
const float THREE_OVER_SIXTEENPI = 0.05968310365946075;
// 1.0 / ( 4.0 * pi )
const float ONE_OVER_FOURPI = 0.07957747154594767;
float rayleighPhase( float cosTheta ) {
return THREE_OVER_SIXTEENPI * ( 1.0 + pow( cosTheta, 2.0 ) );
}
float hgPhase( float cosTheta, float g ) {
float g2 = pow( g, 2.0 );
float inverse = 1.0 / pow( 1.0 - 2.0 * g * cosTheta + g2, 1.5 );
return ONE_OVER_FOURPI * ( ( 1.0 - g2 ) * inverse );
}
void main() {
vec3 direction = normalize( vWorldPosition - cameraPosition );
// optical length
// cutoff angle at 90 to avoid singularity in next formula.
float zenithAngle = acos( max( 0.0, direction.y ) );
float inverse = 1.0 / ( cos( zenithAngle ) + 0.15 * pow( 93.885 - ( ( zenithAngle * 180.0 ) / pi ), -1.253 ) );
float sR = rayleighZenithLength * inverse;
float sM = mieZenithLength * inverse;
// combined extinction factor
vec3 Fex = exp( -( vBetaR * sR + vBetaM * sM ) );
// in scattering
float cosTheta = dot( direction, vSunDirection );
float rPhase = rayleighPhase( cosTheta * 0.5 + 0.5 );
vec3 betaRTheta = vBetaR * rPhase;
float mPhase = hgPhase( cosTheta, mieDirectionalG );
vec3 betaMTheta = vBetaM * mPhase;
vec3 Lin = pow( vSunE * ( ( betaRTheta + betaMTheta ) / ( vBetaR + vBetaM ) ) * ( 1.0 - Fex ), vec3( 1.5 ) );
Lin *= mix( vec3( 1.0 ), pow( vSunE * ( ( betaRTheta + betaMTheta ) / ( vBetaR + vBetaM ) ) * Fex, vec3( 1.0 / 2.0 ) ), clamp( pow( 1.0 - vSunDirection.y, 5.0 ), 0.0, 1.0 ) );
// nightsky
float theta = acos( direction.y ); // elevation --> y-axis, [-pi/2, pi/2]
float phi = atan( direction.z, direction.x ); // azimuth --> x-axis [-pi/2, pi/2]
vec2 uv = vec2( phi, theta ) / vec2( 2.0 * pi, pi ) + vec2( 0.5, 0.0 );
vec3 L0 = vec3( 0.1 ) * Fex;
// composition + solar disc
float sundisc = clamp( ( cosTheta - sunAngularDiameterCos ) * 50000.0, 0.0, 1.0 ) * showSunDisc;
vec3 sundiscColor = ( 760.0 * sundisc ) * min( vSunE * Fex, 80.0 );
vec3 texColor = ( Lin + L0 ) * 0.04 + sundiscColor + vec3( 0.0, 0.0003, 0.00075 );
// Clouds
if ( direction.y > 0.0 && cloudCoverage > 0.0 ) {
// Project to cloud plane (higher elevation = clouds appear lower/closer)
float elevation = mix( 1.0, 0.1, cloudElevation );
vec2 cloudUV = direction.xz / ( direction.y * elevation );
cloudUV *= cloudScale;
cloudUV += time * cloudSpeed;
// Cloud density field
float evolve = time * cloudSpeed * 300.0;
float cloudNoise = clamp( fbm( cloudUV * 1000.0, evolve ) * 0.7 + 0.5, 0.0, 1.0 );
// Large-scale coverage variation: clear gaps next to dense banks
float region = noise( cloudUV * 300.0 ) * 0.37 + 0.5;
float cov = clamp( cloudCoverage + ( region - 0.5 ) * 0.6, 0.0, 1.0 );
// Carve clouds where noise rises above the coverage level
float threshold = 1.0 - cov;
float cloudMask = smoothstep( threshold, threshold + 0.3, cloudNoise );
// Fade clouds near horizon (adjusted by elevation)
float horizonFade = smoothstep( 0.0, 0.03 + 0.06 * cloudElevation, direction.y );
cloudMask *= horizonFade;
// Cloud lighting from the sky's own radiance
float dayFactor = smoothstep( -0.08, 0.3, vSunDirection.y );
vec3 sunColor = vSunE * Fex * 0.22 * 0.04; // 0.22 ~ albedo/pi, 0.04 = exposure; the aerial composite adds the eye-leg extinction
vec3 skyAmbient = Lin * 0.04 + vec3( 0.0, 0.0003, 0.00075 );
// Beer-powder self-shadow from the sampled density
float depth = max( 0.0, cloudNoise - threshold );
float beer = exp( depth * -4.0 );
float powder = 1.0 - beer * beer; // beer*beer == exp(-8*depth)
float shade = mix( 0.45, 1.0, clamp( beer * powder * 2.6, 0.0, 1.0 ) ); // 2.6 = 1/0.385, normalizes beer*powder peak to 1
// Henyey-Greenstein forward lobe ( g = 0.7 ): silver lining on rims toward the sun
float silver = clamp( 0.51 / pow( 1.49 - cosTheta * 1.4, 1.5 ), 0.0, 3.0 ); // 0.51=1-g^2, 1.49=1+g^2, 1.4=2g
float edge = cloudMask * ( 1.0 - cloudMask ) * 4.0;
vec3 cloudColor = skyAmbient + sunColor * shade;
cloudColor += sunColor * silver * edge * 0.6;
cloudColor *= max( dayFactor, 0.03 );
// Cloud opacity via Beer's law: density sets how solid the clouds get
float alpha = ( 1.0 - exp( depth * cloudDensity * -12.0 ) ) * horizonFade;
// Occlude the sun disc/glow behind opaque cloud
texColor -= L0 * 0.04 * alpha;
// Composite through the atmosphere so distant clouds dissolve into haze
vec3 cloudAerial = mix( texColor, cloudColor, Fex );
texColor = mix( texColor, cloudAerial, alpha );
}
gl_FragColor = vec4( texColor, 1.0 );
#include <tonemapping_fragment>
#include <colorspace_fragment>
}`
};
export { Sky };