/**
* @author zz85 / https://github.com/zz85
*
* Based on "A Practical Analytic Model for Daylight"
* aka The Preetham Model, the de facto standard analytic skydome model
* http://www.cs.utah.edu/~shirley/papers/sunsky/sunsky.pdf
*
* First implemented by Simon Wallner
* http://www.simonwallner.at/projects/atmospheric-scattering
*
* Improved by Martin Upitis
* http://blenderartists.org/forum/showthread.php?245954-preethams-sky-impementation-HDR
*
* Three.js integration by zz85 http://twitter.com/blurspline
*/
THREE.Sky = function() {
const shader = THREE.Sky.SkyShader;
const material = new THREE.ShaderMaterial({
fragmentShader: shader.fragmentShader,
vertexShader: shader.vertexShader,
uniforms: THREE.UniformsUtils.clone(shader.uniforms),
side: THREE.BackSide
});
THREE.Mesh.call(this, new THREE.BoxBufferGeometry(1, 1, 1), material);
};
THREE.Sky.prototype = Object.create(THREE.Mesh.prototype);
THREE.Sky.prototype.constructor = THREE.Sky;
THREE.Sky.SkyShader = {
uniforms: {
luminance: { value: 1 },
turbidity: { value: 2 },
rayleigh: { value: 1 },
mieCoefficient: { value: 0.005 },
mieDirectionalG: { value: 0.8 },
sunPosition: { value: new THREE.Vector3() }
},
vertexShader: [
"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;",
"const vec3 up = vec3( 0.0, 1.0, 0.0 );",
// 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-calcuation 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 );",
" vSunDirection = normalize( sunPosition );",
" vSunE = sunIntensity( dot( vSunDirection, up ) );",
" vSunfade = 1.0 - clamp( 1.0 - exp( ( sunPosition.y / 450000.0 ) ), 0.0, 1.0 );",
" float rayleighCoefficient = rayleigh - ( 1.0 * ( 1.0 - vSunfade ) );",
// extinction (absorbtion + out scattering)
// rayleigh coefficients
" vBetaR = totalRayleigh * rayleighCoefficient;",
// mie coefficients
" vBetaM = totalMie( turbidity ) * mieCoefficient;",
"}"
].join("\n"),
fragmentShader: [
"varying vec3 vWorldPosition;",
"varying vec3 vSunDirection;",
"varying float vSunfade;",
"varying vec3 vBetaR;",
"varying vec3 vBetaM;",
"varying float vSunE;",
"uniform float luminance;",
"uniform float mieDirectionalG;",
"const vec3 cameraPos = vec3( 0.0, 0.0, 0.0 );",
// 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;",
"const vec3 up = vec3( 0.0, 1.0, 0.0 );",
// 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 );",
"}",
// Filmic ToneMapping http://filmicgames.com/archives/75
"const float A = 0.15;",
"const float B = 0.50;",
"const float C = 0.10;",
"const float D = 0.20;",
"const float E = 0.02;",
"const float F = 0.30;",
"const float whiteScale = 1.0748724675633854;", // 1.0 / Uncharted2Tonemap(1000.0)
"vec3 Uncharted2Tonemap( vec3 x ) {",
" return ( ( x * ( A * x + C * B ) + D * E ) / ( x * ( A * x + B ) + D * F ) ) - E / F;",
"}",
"void main() {",
// optical length
// cutoff angle at 90 to avoid singularity in next formula.
" float zenithAngle = acos( max( 0.0, dot( up, normalize( vWorldPosition - cameraPos ) ) ) );",
" 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( normalize( vWorldPosition - cameraPos ), 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 - dot( up, vSunDirection ), 5.0 ), 0.0, 1.0 ) );",
// nightsky
" vec3 direction = normalize( vWorldPosition - cameraPos );",
" 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 sundisk = smoothstep( sunAngularDiameterCos, sunAngularDiameterCos + 0.00002, cosTheta );",
" L0 += ( vSunE * 19000.0 * Fex ) * sundisk;",
" vec3 texColor = ( Lin + L0 ) * 0.04 + vec3( 0.0, 0.0003, 0.00075 );",
" vec3 curr = Uncharted2Tonemap( ( log2( 2.0 / pow( luminance, 4.0 ) ) ) * texColor );",
" vec3 color = curr * whiteScale;",
" vec3 retColor = pow( color, vec3( 1.0 / ( 1.2 + ( 1.2 * vSunfade ) ) ) );",
" gl_FragColor = vec4( retColor, 1.0 );",
"}"
].join("\n")
};
AFRAME.registerComponent("skybox", {
schema: {
turbidity: { type: "number", default: 10 },
rayleigh: { type: "number", default: 2 },
luminance: { type: "number", default: 1 },
mieCoefficient: { type: "number", default: 0.005 },
mieDirectionalG: { type: "number", default: 0.8 },
inclination: { type: "number", default: 0 },
azimuth: { type: "number", default: 0 },
distance: { type: "number", default: 8000 }
},
init() {
this.sky = new THREE.Sky();
this.el.setObject3D("mesh", this.sky);
},
update(oldData) {
const uniforms = this.sky.material.uniforms;
if (this.data.turbidity !== oldData.turbidity) {
uniforms.turbidity.value = this.data.turbidity;
}
if (this.data.rayleigh !== oldData.rayleigh) {
uniforms.rayleigh.value = this.data.rayleigh;
}
if (this.data.luminance !== oldData.luminance) {
uniforms.luminance.value = this.data.luminance;
}
if (this.data.mieCoefficient !== oldData.mieCoefficient) {
uniforms.mieCoefficient.value = this.data.mieCoefficient;
}
if (this.data.mieDirectionalG !== oldData.mieDirectionalG) {
uniforms.mieDirectionalG.value = this.data.mieDirectionalG;
}
if (
this.data.inclination !== oldData.inclination ||
this.data.azimuth !== oldData.azimuth ||
this.data.distance !== oldData.distance
) {
const theta = Math.PI * (this.data.inclination - 0.5);
const phi = 2 * Math.PI * (this.data.azimuth - 0.5);
const distance = this.data.distance;
const x = distance * Math.cos(phi);
const y = distance * Math.sin(phi) * Math.sin(theta);
const z = distance * Math.sin(phi) * Math.cos(theta);
uniforms.sunPosition.value.set(x, y, z).normalize();
// HACK Remove this if condition and always set the scale based on distance when the existing environments
// have their sky scales set to 1.
if (this.el.object3D.scale.x === 1) {
this.sky.scale.set(distance, distance, distance);
}
}
},
remove() {
this.el.removeObject3D("mesh");
}
});