242 lines
7.6 KiB
JavaScript
242 lines
7.6 KiB
JavaScript
import {
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BackSide,
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BoxGeometry,
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Mesh,
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Vector3,
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NodeMaterial
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} from 'three/webgpu';
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import { Fn, float, vec3, acos, add, mul, clamp, cos, dot, exp, max, mix, modelViewProjection, normalize, positionWorld, pow, smoothstep, sub, varying, varyingProperty, vec4, uniform, cameraPosition } from 'three/tsl';
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/**
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* Represents a skydome for scene backgrounds. Based on [A Practical Analytic Model for Daylight]{@link https://www.researchgate.net/publication/220720443_A_Practical_Analytic_Model_for_Daylight}
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* aka The Preetham Model, the de facto standard for analytical skydomes.
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*
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* Note that this class can only be used with {@link WebGLRenderer}.
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* When using {@link WebGPURenderer}, use {@link SkyMesh}.
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*
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* More references:
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*
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* - {@link http://simonwallner.at/project/atmospheric-scattering/}
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* - {@link http://blenderartists.org/forum/showthread.php?245954-preethams-sky-impementation-HDR}
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*
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* ```js
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* const sky = new SkyMesh();
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* sky.scale.setScalar( 10000 );
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* scene.add( sky );
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* ```
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*
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* @augments Mesh
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* @three_import import { SkyMesh } from 'three/addons/objects/SkyMesh.js';
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*/
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class SkyMesh extends Mesh {
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/**
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* Constructs a new skydome.
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*/
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constructor() {
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const material = new NodeMaterial();
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super( new BoxGeometry( 1, 1, 1 ), material );
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/**
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* The turbidity uniform.
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*
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* @type {UniformNode<float>}
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*/
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this.turbidity = uniform( 2 );
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/**
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* The rayleigh uniform.
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*
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* @type {UniformNode<float>}
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*/
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this.rayleigh = uniform( 1 );
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/**
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* The mieCoefficient uniform.
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*
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* @type {UniformNode<float>}
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*/
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this.mieCoefficient = uniform( 0.005 );
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/**
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* The mieDirectionalG uniform.
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*
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* @type {UniformNode<float>}
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*/
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this.mieDirectionalG = uniform( 0.8 );
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/**
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* The sun position uniform.
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*
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* @type {UniformNode<vec3>}
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*/
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this.sunPosition = uniform( new Vector3() );
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/**
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* The up position.
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*
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* @type {UniformNode<vec3>}
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*/
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this.upUniform = uniform( new Vector3( 0, 1, 0 ) );
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/**
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* This flag can be used for type testing.
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*
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* @type {boolean}
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* @readonly
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* @default true
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*/
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this.isSky = true;
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const vertexNode = /*@__PURE__*/ Fn( () => {
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// constants for atmospheric scattering
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const e = float( 2.71828182845904523536028747135266249775724709369995957 );
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// const pi = float( 3.141592653589793238462643383279502884197169 );
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// wavelength of used primaries, according to preetham
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// const lambda = vec3( 680E-9, 550E-9, 450E-9 );
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// this pre-calculation replaces older TotalRayleigh(vec3 lambda) function:
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// (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))
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const totalRayleigh = vec3( 5.804542996261093E-6, 1.3562911419845635E-5, 3.0265902468824876E-5 );
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// mie stuff
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// K coefficient for the primaries
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// const v = float( 4.0 );
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// const K = vec3( 0.686, 0.678, 0.666 );
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// MieConst = pi * pow( ( 2.0 * pi ) / lambda, vec3( v - 2.0 ) ) * K
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const MieConst = vec3( 1.8399918514433978E14, 2.7798023919660528E14, 4.0790479543861094E14 );
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// earth shadow hack
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// cutoffAngle = pi / 1.95;
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const cutoffAngle = float( 1.6110731556870734 );
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const steepness = float( 1.5 );
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const EE = float( 1000.0 );
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// varying sun position
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const vSunDirection = normalize( this.sunPosition );
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varyingProperty( 'vec3', 'vSunDirection' ).assign( vSunDirection );
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// varying sun intensity
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const angle = dot( vSunDirection, this.upUniform );
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const zenithAngleCos = clamp( angle, - 1, 1 );
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const sunIntensity = EE.mul( max( 0.0, float( 1.0 ).sub( pow( e, cutoffAngle.sub( acos( zenithAngleCos ) ).div( steepness ).negate() ) ) ) );
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varyingProperty( 'float', 'vSunE' ).assign( sunIntensity );
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// varying sun fade
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const vSunfade = float( 1.0 ).sub( clamp( float( 1.0 ).sub( exp( this.sunPosition.y.div( 450000.0 ) ) ), 0, 1 ) );
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varyingProperty( 'float', 'vSunfade' ).assign( vSunfade );
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// varying vBetaR
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const rayleighCoefficient = this.rayleigh.sub( float( 1.0 ).mul( float( 1.0 ).sub( vSunfade ) ) );
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// extinction (absorption + out scattering)
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// rayleigh coefficients
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varyingProperty( 'vec3', 'vBetaR' ).assign( totalRayleigh.mul( rayleighCoefficient ) );
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// varying vBetaM
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const c = float( 0.2 ).mul( this.turbidity ).mul( 10E-18 );
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const totalMie = float( 0.434 ).mul( c ).mul( MieConst );
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varyingProperty( 'vec3', 'vBetaM' ).assign( totalMie.mul( this.mieCoefficient ) );
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// position
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const position = modelViewProjection;
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position.z.assign( position.w ); // set z to camera.far
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return position;
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} )();
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const fragmentNode = /*@__PURE__*/ Fn( () => {
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const vSunDirection = varying( vec3(), 'vSunDirection' );
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const vSunE = varying( float(), 'vSunE' );
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const vSunfade = varying( float(), 'vSunfade' );
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const vBetaR = varying( vec3(), 'vBetaR' );
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const vBetaM = varying( vec3(), 'vBetaM' );
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// constants for atmospheric scattering
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const pi = float( 3.141592653589793238462643383279502884197169 );
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// optical length at zenith for molecules
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const rayleighZenithLength = float( 8.4E3 );
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const mieZenithLength = float( 1.25E3 );
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// 66 arc seconds -> degrees, and the cosine of that
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const sunAngularDiameterCos = float( 0.999956676946448443553574619906976478926848692873900859324 );
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// 3.0 / ( 16.0 * pi )
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const THREE_OVER_SIXTEENPI = float( 0.05968310365946075 );
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// 1.0 / ( 4.0 * pi )
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const ONE_OVER_FOURPI = float( 0.07957747154594767 );
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//
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const direction = normalize( positionWorld.sub( cameraPosition ) );
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// optical length
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// cutoff angle at 90 to avoid singularity in next formula.
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const zenithAngle = acos( max( 0.0, dot( this.upUniform, direction ) ) );
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const inverse = float( 1.0 ).div( cos( zenithAngle ).add( float( 0.15 ).mul( pow( float( 93.885 ).sub( zenithAngle.mul( 180.0 ).div( pi ) ), - 1.253 ) ) ) );
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const sR = rayleighZenithLength.mul( inverse );
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const sM = mieZenithLength.mul( inverse );
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// combined extinction factor
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const Fex = exp( mul( vBetaR, sR ).add( mul( vBetaM, sM ) ).negate() );
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// in scattering
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const cosTheta = dot( direction, vSunDirection );
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// betaRTheta
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const c = cosTheta.mul( 0.5 ).add( 0.5 );
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const rPhase = THREE_OVER_SIXTEENPI.mul( float( 1.0 ).add( pow( c, 2.0 ) ) );
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const betaRTheta = vBetaR.mul( rPhase );
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// betaMTheta
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const g2 = pow( this.mieDirectionalG, 2.0 );
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const inv = float( 1.0 ).div( pow( float( 1.0 ).sub( float( 2.0 ).mul( this.mieDirectionalG ).mul( cosTheta ) ).add( g2 ), 1.5 ) );
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const mPhase = ONE_OVER_FOURPI.mul( float( 1.0 ).sub( g2 ) ).mul( inv );
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const betaMTheta = vBetaM.mul( mPhase );
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const Lin = pow( vSunE.mul( add( betaRTheta, betaMTheta ).div( add( vBetaR, vBetaM ) ) ).mul( sub( 1.0, Fex ) ), vec3( 1.5 ) );
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Lin.mulAssign( mix( vec3( 1.0 ), pow( vSunE.mul( add( betaRTheta, betaMTheta ).div( add( vBetaR, vBetaM ) ) ).mul( Fex ), vec3( 1.0 / 2.0 ) ), clamp( pow( sub( 1.0, dot( this.upUniform, vSunDirection ) ), 5.0 ), 0.0, 1.0 ) ) );
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// nightsky
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const L0 = vec3( 0.1 ).mul( Fex );
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// composition + solar disc
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const sundisk = smoothstep( sunAngularDiameterCos, sunAngularDiameterCos.add( 0.00002 ), cosTheta );
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L0.addAssign( vSunE.mul( 19000.0 ).mul( Fex ).mul( sundisk ) );
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const texColor = add( Lin, L0 ).mul( 0.04 ).add( vec3( 0.0, 0.0003, 0.00075 ) );
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const retColor = pow( texColor, vec3( float( 1.0 ).div( float( 1.2 ).add( vSunfade.mul( 1.2 ) ) ) ) );
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return vec4( retColor, 1.0 );
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} )();
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material.side = BackSide;
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material.depthWrite = false;
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material.vertexNode = vertexNode;
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material.fragmentNode = fragmentNode;
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}
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}
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export { SkyMesh };
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