pex-renderer
Version:
Physically Based Renderer for Pex
203 lines (147 loc) • 6.55 kB
JavaScript
module.exports = /* glsl */ `
/*
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
Plask / Pex integration by Marcin Ignac http://twitter.com/marcinignac, 2015-09
*/
vec3 cameraPos = vec3(0.0, 0.0, 0.0);
const float luminance = 1.0;
const float turbidity = 10.0;
const float reileigh = 2.0;
const float mieCoefficient = 0.005;
const float mieDirectionalG = 0.8;
//uniform float luminance; //1.0
//uniform float turbidity; //10.0
//uniform float reileigh; //2.0
//uniform float mieCoefficient; //0.005
//uniform float mieDirectionalG; //0.8
float reileighCoefficient = reileigh;
// constants for atmospheric scattering
const float e = 2.71828182845904523536028747135266249775724709369995957;
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)
const float pn = 0.035; // depolatization factor for standard air
// wavelength of used primaries, according to preetham
const vec3 lambda = vec3(680E-9, 550E-9, 450E-9);
// mie stuff
// K coefficient for the primaries
const vec3 K = vec3(0.686, 0.678, 0.666);
const float v = 4.0;
// 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);
const float EE = 1000.0;
const float sunAngularDiameterCos = 0.999956676946448443553574619906976478926848692873900859324;
// 66 arc seconds -> degrees, and the cosine of that
// earth shadow hack
const float cutoffAngle = pi/1.95;
const float steepness = 1.5;
vec3 totalRayleigh(vec3 lambda)
{
return (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));
}
// A simplied version of the total Reayleigh scattering to works on browsers that use ANGLE
vec3 simplifiedRayleigh()
{
return 0.0005 / vec3(94, 40, 18);
}
float rayleighPhase(float cosTheta)
{
return (3.0 / (16.0*pi)) * (1.0 + pow(cosTheta, 2.0));
// return (1.0 / (3.0*pi)) * (1.0 + pow(cosTheta, 2.0));
// return (3.0 / 4.0) * (1.0 + pow(cosTheta, 2.0));
}
vec3 totalMie(vec3 lambda, vec3 K, float T)
{
float c = (0.2 * T ) * 10E-18;
return 0.434 * c * pi * pow((2.0 * pi) / lambda, vec3(v - 2.0)) * K;
}
float hgPhase(float cosTheta, float g)
{
return (1.0 / (4.0*pi)) * ((1.0 - pow(g, 2.0)) / pow(1.0 - 2.0*g*cosTheta + pow(g, 2.0), 1.5));
}
float sunIntensity(float zenithAngleCos)
{
return EE * max(0.0, 1.0 - exp(-((cutoffAngle - acos(zenithAngleCos))/steepness)));
}
// float logLuminance(vec3 c)
// {
// return log(c.r * 0.2126 + c.g * 0.7152 + c.b * 0.0722);
// }
// Filmic ToneMapping http://filmicgames.com/archives/75
float A = 0.15;
float B = 0.50;
float C = 0.10;
float D = 0.20;
float E = 0.02;
float F = 0.30;
float W = 1000.0;
vec3 Uncharted2Tonemap(vec3 x)
{
return ((x*(A*x+C*B)+D*E)/(x*(A*x+B)+D*F))-E/F;
}
vec3 sky(vec3 sunPosition, vec3 worldNormal) {
vec3 sunDirection = normalize(sunPosition);
float sunfade = 1.0-clamp(1.0-exp((sunPosition.y/450000.0)),0.0,1.0);
// luminance = 1.0 ;// vWorldPosition.y / 450000. + 0.5; //sunPosition.y / 450000. * 1. + 0.5;
// gl_FragColor = vec4(sunfade, sunfade, sunfade, 1.0);
reileighCoefficient = reileighCoefficient - (1.0* (1.0-sunfade));
float sunE = sunIntensity(dot(sunDirection, up));
// extinction (absorbtion + out scattering)
// rayleigh coefficients
//vec3 betaR = totalRayleigh(lambda) * reileighCoefficient;
vec3 betaR = simplifiedRayleigh() * reileighCoefficient;
// mie coefficients
vec3 betaM = totalMie(lambda, K, turbidity) * mieCoefficient;
// optical length
// cutoff angle at 90 to avoid singularity in next formula.
//float zenithAngle = acos(max(0.0, dot(up, normalize(vWorldPosition - cameraPos))));
float zenithAngle = acos(max(0.0, dot(up, normalize(worldNormal))));
float sR = rayleighZenithLength / (cos(zenithAngle) + 0.15 * pow(93.885 - ((zenithAngle * 180.0) / pi), -1.253));
float sM = mieZenithLength / (cos(zenithAngle) + 0.15 * pow(93.885 - ((zenithAngle * 180.0) / pi), -1.253));
// combined extinction factor
vec3 Fex = exp(-(betaR * sR + betaM * sM));
// in scattering
float cosTheta = dot(normalize(worldNormal), sunDirection);
float rPhase = rayleighPhase(cosTheta*0.5+0.5);
vec3 betaRTheta = betaR * rPhase;
float mPhase = hgPhase(cosTheta, mieDirectionalG);
vec3 betaMTheta = betaM * mPhase;
vec3 Lin = pow(sunE * ((betaRTheta + betaMTheta) / (betaR + betaM)) * (1.0 - Fex),vec3(1.5));
Lin *= mix(vec3(1.0),pow(sunE * ((betaRTheta + betaMTheta) / (betaR + betaM)) * Fex,vec3(1.0/2.0)),clamp(pow(1.0-dot(up, sunDirection),5.0),0.0,1.0));
//nightsky
vec3 direction = normalize(worldNormal);
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 = texture2D(skySampler, uv).rgb+0.1 * Fex;
vec3 L0 = vec3(0.1) * Fex;
// composition + solar disc
//if (cosTheta > sunAngularDiameterCos)
float sundisk = smoothstep(sunAngularDiameterCos,sunAngularDiameterCos+0.00002,cosTheta);
// if (normalize(vWorldPosition - cameraPos).y>0.0)
L0 += (sunE * 19000.0 * Fex)*sundisk;
vec3 whiteScale = 1.0/Uncharted2Tonemap(vec3(W));
vec3 texColor = (Lin+L0);
texColor *= 0.04 ;
texColor += vec3(0.0,0.001,0.0025)*0.3;
float g_fMaxLuminance = 1.0;
float fLumScaled = 0.1 / luminance;
float fLumCompressed = (fLumScaled * (1.0 + (fLumScaled / (g_fMaxLuminance * g_fMaxLuminance)))) / (1.0 + fLumScaled);
float ExposureBias = fLumCompressed;
vec3 curr = Uncharted2Tonemap((log2(2.0/pow(luminance,4.0)))*texColor);
//vec3 curr = texColor;
vec3 color = curr*whiteScale;
vec3 retColor = pow(color,vec3(1.0/(1.2+(1.2*sunfade))));
//VRG hack
retColor = pow(retColor, vec3(2.2));
return retColor;
}
`