mirror of
https://github.com/tengge1/ShadowEditor.git
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239 lines
7.6 KiB
JavaScript
239 lines
7.6 KiB
JavaScript
/**
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* @author zz85 / https://github.com/zz85
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*
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* Based on "A Practical Analytic Model for Daylight"
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* aka The Preetham Model, the de facto standard analytic skydome model
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* http://www.cs.utah.edu/~shirley/papers/sunsky/sunsky.pdf
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*
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* First implemented by Simon Wallner
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* http://www.simonwallner.at/projects/atmospheric-scattering
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*
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* Improved by Martin Upitis
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* http://blenderartists.org/forum/showthread.php?245954-preethams-sky-impementation-HDR
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*
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* Three.js integration by zz85 http://twitter.com/blurspline
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*/
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THREE.ShaderLib[ 'sky' ] = {
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uniforms: {
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luminance: { value: 1 },
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turbidity: { value: 2 },
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rayleigh: { value: 1 },
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mieCoefficient: { value: 0.005 },
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mieDirectionalG: { value: 0.8 },
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sunPosition: { value: new THREE.Vector3() }
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},
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vertexShader: [
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"uniform vec3 sunPosition;",
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"uniform float rayleigh;",
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"uniform float turbidity;",
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"uniform float mieCoefficient;",
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"varying vec3 vWorldPosition;",
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"varying vec3 vSunDirection;",
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"varying float vSunfade;",
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"varying vec3 vBetaR;",
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"varying vec3 vBetaM;",
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"varying float vSunE;",
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"const vec3 up = vec3( 0.0, 1.0, 0.0 );",
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// constants for atmospheric scattering
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"const float e = 2.71828182845904523536028747135266249775724709369995957;",
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"const float pi = 3.141592653589793238462643383279502884197169;",
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// wavelength of used primaries, according to preetham
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"const vec3 lambda = vec3( 680E-9, 550E-9, 450E-9 );",
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// this pre-calcuation 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 vec3 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 float v = 4.0;",
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"const vec3 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 vec3 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 float cutoffAngle = 1.6110731556870734;",
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"const float steepness = 1.5;",
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"const float EE = 1000.0;",
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"float sunIntensity( float zenithAngleCos )",
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"{",
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"zenithAngleCos = clamp( zenithAngleCos, -1.0, 1.0 );",
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"return EE * max( 0.0, 1.0 - pow( e, -( ( cutoffAngle - acos( zenithAngleCos ) ) / steepness ) ) );",
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"}",
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"vec3 totalMie( float T )",
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"{",
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"float c = ( 0.2 * T ) * 10E-18;",
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"return 0.434 * c * MieConst;",
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"}",
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"void main() {",
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"vec4 worldPosition = modelMatrix * vec4( position, 1.0 );",
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"vWorldPosition = worldPosition.xyz;",
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"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
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"vSunDirection = normalize( sunPosition );",
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"vSunE = sunIntensity( dot( vSunDirection, up ) );",
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"vSunfade = 1.0 - clamp( 1.0 - exp( ( sunPosition.y / 450000.0 ) ), 0.0, 1.0 );",
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"float rayleighCoefficient = rayleigh - ( 1.0 * ( 1.0 - vSunfade ) );",
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// extinction (absorbtion + out scattering)
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// rayleigh coefficients
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"vBetaR = totalRayleigh * rayleighCoefficient;",
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// mie coefficients
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"vBetaM = totalMie( turbidity ) * mieCoefficient;",
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"}"
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].join( "\n" ),
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fragmentShader: [
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"varying vec3 vWorldPosition;",
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"varying vec3 vSunDirection;",
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"varying float vSunfade;",
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"varying vec3 vBetaR;",
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"varying vec3 vBetaM;",
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"varying float vSunE;",
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"uniform float luminance;",
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"uniform float mieDirectionalG;",
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"const vec3 cameraPos = vec3( 0.0, 0.0, 0.0 );",
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// constants for atmospheric scattering
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"const float pi = 3.141592653589793238462643383279502884197169;",
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"const float n = 1.0003;", // refractive index of air
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"const float N = 2.545E25;", // number of molecules per unit volume for air at
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// 288.15K and 1013mb (sea level -45 celsius)
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// optical length at zenith for molecules
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"const float rayleighZenithLength = 8.4E3;",
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"const float mieZenithLength = 1.25E3;",
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"const vec3 up = vec3( 0.0, 1.0, 0.0 );",
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// 66 arc seconds -> degrees, and the cosine of that
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"const float sunAngularDiameterCos = 0.999956676946448443553574619906976478926848692873900859324;",
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// 3.0 / ( 16.0 * pi )
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"const float THREE_OVER_SIXTEENPI = 0.05968310365946075;",
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// 1.0 / ( 4.0 * pi )
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"const float ONE_OVER_FOURPI = 0.07957747154594767;",
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"float rayleighPhase( float cosTheta )",
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"{",
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"return THREE_OVER_SIXTEENPI * ( 1.0 + pow( cosTheta, 2.0 ) );",
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"}",
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"float hgPhase( float cosTheta, float g )",
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"{",
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"float g2 = pow( g, 2.0 );",
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"float inverse = 1.0 / pow( 1.0 - 2.0 * g * cosTheta + g2, 1.5 );",
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"return ONE_OVER_FOURPI * ( ( 1.0 - g2 ) * inverse );",
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"}",
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// Filmic ToneMapping http://filmicgames.com/archives/75
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"const float A = 0.15;",
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"const float B = 0.50;",
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"const float C = 0.10;",
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"const float D = 0.20;",
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"const float E = 0.02;",
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"const float F = 0.30;",
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"const float whiteScale = 1.0748724675633854;", // 1.0 / Uncharted2Tonemap(1000.0)
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"vec3 Uncharted2Tonemap( vec3 x )",
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"{",
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"return ( ( x * ( A * x + C * B ) + D * E ) / ( x * ( A * x + B ) + D * F ) ) - E / F;",
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"}",
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"void main() ",
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"{",
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// optical length
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// cutoff angle at 90 to avoid singularity in next formula.
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"float zenithAngle = acos( max( 0.0, dot( up, normalize( vWorldPosition - cameraPos ) ) ) );",
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"float inverse = 1.0 / ( cos( zenithAngle ) + 0.15 * pow( 93.885 - ( ( zenithAngle * 180.0 ) / pi ), -1.253 ) );",
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"float sR = rayleighZenithLength * inverse;",
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"float sM = mieZenithLength * inverse;",
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// combined extinction factor
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"vec3 Fex = exp( -( vBetaR * sR + vBetaM * sM ) );",
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// in scattering
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"float cosTheta = dot( normalize( vWorldPosition - cameraPos ), vSunDirection );",
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"float rPhase = rayleighPhase( cosTheta * 0.5 + 0.5 );",
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"vec3 betaRTheta = vBetaR * rPhase;",
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"float mPhase = hgPhase( cosTheta, mieDirectionalG );",
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"vec3 betaMTheta = vBetaM * mPhase;",
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"vec3 Lin = pow( vSunE * ( ( betaRTheta + betaMTheta ) / ( vBetaR + vBetaM ) ) * ( 1.0 - Fex ), vec3( 1.5 ) );",
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"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 ) );",
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//nightsky
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"vec3 direction = normalize( vWorldPosition - cameraPos );",
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"float theta = acos( direction.y ); // elevation --> y-axis, [-pi/2, pi/2]",
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"float phi = atan( direction.z, direction.x ); // azimuth --> x-axis [-pi/2, pi/2]",
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"vec2 uv = vec2( phi, theta ) / vec2( 2.0 * pi, pi ) + vec2( 0.5, 0.0 );",
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"vec3 L0 = vec3( 0.1 ) * Fex;",
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// composition + solar disc
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"float sundisk = smoothstep( sunAngularDiameterCos, sunAngularDiameterCos + 0.00002, cosTheta );",
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"L0 += ( vSunE * 19000.0 * Fex ) * sundisk;",
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"vec3 texColor = ( Lin + L0 ) * 0.04 + vec3( 0.0, 0.0003, 0.00075 );",
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"vec3 curr = Uncharted2Tonemap( ( log2( 2.0 / pow( luminance, 4.0 ) ) ) * texColor );",
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"vec3 color = curr * whiteScale;",
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"vec3 retColor = pow( color, vec3( 1.0 / ( 1.2 + ( 1.2 * vSunfade ) ) ) );",
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"gl_FragColor.rgb = retColor;",
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"gl_FragColor.a = 1.0;",
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"}"
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].join( "\n" )
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};
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THREE.Sky = function () {
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var skyShader = THREE.ShaderLib[ "sky" ];
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var skyUniforms = THREE.UniformsUtils.clone( skyShader.uniforms );
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var skyMat = new THREE.ShaderMaterial( {
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fragmentShader: skyShader.fragmentShader,
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vertexShader: skyShader.vertexShader,
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uniforms: skyUniforms,
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side: THREE.BackSide
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} );
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var skyGeo = new THREE.SphereBufferGeometry( 450000, 32, 15 );
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var skyMesh = new THREE.Mesh( skyGeo, skyMat );
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// Expose variables
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this.mesh = skyMesh;
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this.uniforms = skyUniforms;
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};
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