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paysages3d/lib_paysages/atmosphere/bruneton.c

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#include "public.h"
/*
* Atmospheric scattering, based on E. Bruneton and F.Neyret work.
* http://evasion.inrialpes.fr/~Eric.Bruneton/
*/
#if 1
#include <math.h>
#include <stdlib.h>
#include "../system.h"
#define TRANSMITTANCE_NON_LINEAR
#define INSCATTER_NON_LINEAR
#define FIX
static const double Rg = 6360.0;
static const double Rt = 6420.0;
static const double RL = 6421.0;
static const double exposure = 0.4;
static const double ISun = 100.0;
#define RES_MU 128
#define RES_MU_S 32
#define RES_R 32
#define RES_NU 8
#define TRANSMITTANCE_INTEGRAL_SAMPLES 500
/*#define SKY_W 64
#define SKY_H 16*/
#define SKY_W 640
#define SKY_H 160
typedef struct
{
int xsize;
int ysize;
Color* data;
} Texture2D;
typedef struct
{
int xsize;
int ysize;
int zsize;
Color* data;
} Texture3D;
Texture2D _transmittanceTexture = {0, 0, 0};
Texture2D _irrDeltaETexture;
Texture3D _inscatterSampler;
// Rayleigh
static const double HR = 8.0;
static const Color betaR = {5.8e-3, 1.35e-2, 3.31e-2, 1.0};
// Mie
// DEFAULT
static const double HM = 1.2;
static const Vector3 betaMSca = {4e-3, 4e-3, 4e-3};
static const Vector3 betaMEx = {4e-3 / 0.9, 4e-3 / 0.9, 4e-3 / 0.9};
static const double mieG = 0.8;
// CLEAR SKY
/*static const float HM = 1.2;
static const vec3 betaMSca = vec3(20e-3);
static const vec3 betaMEx = betaMSca / 0.9;
static const float mieG = 0.76;*/
// PARTLY CLOUDY
/*static const float HM = 3.0;
static const vec3 betaMSca = vec3(3e-3);
static const vec3 betaMEx = betaMSca / 0.9;
static const float mieG = 0.65;*/
#define step(_a_,_b_) ((_a_) < (_b_) ? 0 : 1)
#define max(_a_,_b_) ((_a_) > (_b_) ? (_a_) : (_b_))
#define min(_a_,_b_) ((_a_) < (_b_) ? (_a_) : (_b_))
#define sign(_a_) ((_a_) < 0.0 ? -1.0 : ((_a_) > 0.0 ? 1.0 : 0.0))
#define mix(_x_,_y_,_a_) ((_x_) * (1.0 - (_a_)) + (_y_) * (_a_))
static inline Color vec4mix(Color v1, Color v2, double a)
{
v1.r = mix(v1.r, v2.r, a);
v1.g = mix(v1.g, v2.g, a);
v1.b = mix(v1.b, v2.b, a);
v1.a = mix(v1.a, v2.a, a);
return v1;
}
static inline double clamp(double x, double minVal, double maxVal)
{
if (x < minVal)
{
x = minVal;
}
return (x > maxVal) ? maxVal : x;
}
static inline double smoothstep(double edge0, double edge1, double x)
{
double t = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);
return t * t * (3.0 - 2.0 * t);
}
static inline void _fixVec4Min(Color* vec, double minVal)
{
if (vec->r < minVal) { vec->r = minVal; }
if (vec->g < minVal) { vec->g = minVal; }
if (vec->b < minVal) { vec->b = minVal; }
if (vec->a < minVal) { vec->a = minVal; }
}
static inline Color vec4max(Color vec, double minVal)
{
if (vec.r < minVal) { vec.r = minVal; }
if (vec.g < minVal) { vec.g = minVal; }
if (vec.b < minVal) { vec.b = minVal; }
if (vec.a < minVal) { vec.a = minVal; }
return vec;
}
static inline Vector3 vec3(double x, double y, double z)
{
Vector3 result;
result.x = x;
result.y = y;
result.z = z;
return result;
}
static inline Color vec4(double r, double g, double b, double a)
{
Color result;
result.r = r;
result.g = g;
result.b = b;
result.a = a;
return result;
}
static Color _texture2D(Texture2D* tex, double x, double y)
{
if (x < 0.0) x = 0.0;
if (x > 1.0) x = 1.0;
if (y < 0.0) y = 0.0;
if (y > 1.0) y = 1.0;
/* TODO Interpolation */
int ix = (int)round(x * ((double)(tex->xsize - 1)) + 0.5);
int iy = (int)round(y * ((double)(tex->ysize - 1)) + 0.5);
return tex->data[iy * tex->xsize + ix];
}
static Color _texture3D(Texture3D* tex, Vector3 p)
{
/* TODO Interpolation */
return tex->data[(int)(p.z * (tex->zsize - 1)) * tex->ysize * tex->xsize + (int)(p.y * (tex->ysize - 1)) * tex->xsize + (int)(p.x * (tex->xsize - 1))];
}
static Color _texture4D(Texture3D* tex3d, double r, double mu, double muS, double nu)
{
double H = sqrt(Rt * Rt - Rg * Rg);
double rho = sqrt(r * r - Rg * Rg);
#ifdef INSCATTER_NON_LINEAR
double rmu = r * mu;
double delta = rmu * rmu - r * r + Rg * Rg;
Color cst = (rmu < 0.0 && delta > 0.0) ? vec4(1.0, 0.0, 0.0, 0.5 - 0.5 / (double)(RES_MU)) : vec4(-1.0, H * H, H, 0.5 + 0.5 / (double)(RES_MU));
double uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
double uMu = cst.a + (rmu * cst.r + sqrt(delta + cst.g)) / (rho + cst.b) * (0.5 - 1.0 / (double)(RES_MU));
// paper formula
//float uMuS = 0.5 / (double)(RES_MU_S) + max((1.0 - exp(-3.0 * muS - 0.6)) / (1.0 - exp(-3.6)), 0.0) * (1.0 - 1.0 / (double)(RES_MU_S));
// better formula
double uMuS = 0.5 / (double)(RES_MU_S) + (atan(max(muS, -0.1975) * tan(1.26 * 1.1)) / 1.1 + (1.0 - 0.26)) * 0.5 * (1.0 - 1.0 / (double)(RES_MU_S));
#else
float uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
float uMu = 0.5 / (double)(RES_MU) + (mu + 1.0) / 2.0 * (1.0 - 1.0 / (double)(RES_MU));
float uMuS = 0.5 / (double)(RES_MU_S) + max(muS + 0.2, 0.0) / 1.2 * (1.0 - 1.0 / (double)(RES_MU_S));
#endif
double lerp = (nu + 1.0) / 2.0 * ((double)(RES_NU) - 1.0);
double uNu = floor(lerp);
lerp = lerp - uNu;
return vec4mix(_texture3D(tex3d, vec3((uNu + uMuS + 1.0) / (double)(RES_NU), uMu, uR)), _texture3D(tex3d, vec3((uNu + uMuS) / (double)(RES_NU), uMu, uR)), lerp);
}
/* Rayleigh phase function */
static double _phaseFunctionR(double mu)
{
return (3.0 / (16.0 * M_PI)) * (1.0 + mu * mu);
}
/* Mie phase function */
static double _phaseFunctionM(double mu)
{
return 1.5 * 1.0 / (4.0 * M_PI) * (1.0 - mieG * mieG) * pow(1.0 + (mieG * mieG) - 2.0 * mieG * mu, -3.0 / 2.0) * (1.0 + mu * mu) / (2.0 + mieG * mieG);
}
/* approximated single Mie scattering (cf. approximate Cm in paragraph "Angular precision") */
Color getMie(Color rayMie)
{
Color result;
result.r = rayMie.r * rayMie.a / max(rayMie.r, 1e-4) * (betaR.r / betaR.r);
result.g = rayMie.g * rayMie.a / max(rayMie.r, 1e-4) * (betaR.r / betaR.g);
result.b = rayMie.b * rayMie.a / max(rayMie.r, 1e-4) * (betaR.r / betaR.b);
result.a = 1.0;
return result;
}
/* optical depth for ray (r,mu) of length d, using analytic formula
(mu=cos(view zenith angle)), intersections with ground ignored
H=height scale of exponential density function */
static double _opticalDepth(double H, double r, double mu, double d)
{
double a = sqrt((0.5 / H) * r);
double ax = a * (mu);
double ay = a * (mu + d / r);
double axs = sign(ax);
double ays = sign(ay);
double axq = ax * ax;
double ayq = ay * ay;
double x = ays > axs ? exp(axq) : 0.0;
double yx = axs / (2.3193 * fabs(ax) + sqrt(1.52 * axq + 4.0));
double yy = ays / (2.3193 * fabs(ay) + sqrt(1.52 * ayq + 4.0)) * exp(-d / H * (d / (2.0 * r) + mu));
return sqrt((6.2831 * H) * r) * exp((Rg - r) / H) * (x + yx - yy);
}
static Texture3D _precomputeInscatterSampler()
{
Texture3D result;
int x, y;
#if 0
result.xsize = 256;
result.ysize = 64;
result.data = malloc(sizeof(Color) * result.xsize * result.ysize); /* TODO free */
for (x = 0; x < result.xsize; x++)
{
for (y = 0; y < result.ysize; y++)
{
double r, muS;
_getTransmittanceRMu((double)x / result.xsize, (double)y / result.ysize, &r, &muS);
double depth1 = _opticalDepthTransmittance(HR, r, muS);
double depth2 = _opticalDepthTransmittance(HM, r, muS);
Color trans;
trans.r = exp(-(betaR.r * depth1 + betaMEx.x * depth2));
trans.g = exp(-(betaR.g * depth1 + betaMEx.y * depth2));
trans.b = exp(-(betaR.b * depth1 + betaMEx.z * depth2));
trans.a = 1.0;
result.data[y * result.xsize + x] = trans; /* Eq (5) */
}
}
#endif
return result;
}
static inline void _getTransmittanceUV(double r, double mu, double* u, double* v)
{
#ifdef TRANSMITTANCE_NON_LINEAR
*v = sqrt((r - Rg) / (Rt - Rg));
*u = atan((mu + 0.15) / (1.0 + 0.15) * tan(1.5)) / 1.5;
#else
*v = (r - Rg) / (Rt - Rg);
*u = (mu + 0.15) / (1.0 + 0.15);
#endif
}
/* transmittance(=transparency) of atmosphere for infinite ray (r,mu)
(mu=cos(view zenith angle)), intersections with ground ignored */
static Color _transmittance(double r, double mu)
{
double u, v;
_getTransmittanceUV(r, mu, &u, &v);
return _texture2D(&_transmittanceTexture, u, v);
}
static void _getIrradianceRMuS(double x, double y, double* r, double* muS)
{
*r = Rg + y * (Rt - Rg);
*muS = -0.2 + x * (1.0 + 0.2);
}
static Texture2D _precomputeIrrDeltaETexture()
{
Texture2D result;
int x, y;
result.xsize = SKY_W;
result.ysize = SKY_H;
result.data = malloc(sizeof(Color) * result.xsize * result.ysize); /* TODO free */
/* Irradiance program */
for (x = 0; x < result.xsize; x++)
{
for (y = 0; y < result.ysize; y++)
{
double r, muS, u, v;
Color trans, irr;
_getIrradianceRMuS((double)x / result.xsize, (double)y / result.ysize, &r, &muS);
trans = _transmittance(r, muS);
_getTransmittanceUV(r, muS, &u, &v);
//printf("%d %d -> %f %f -> %f %f %f\n", x, y, u, v, trans.r, trans.g, trans.b);
irr.r = trans.r * max(muS, 0.0);
irr.g = trans.g * max(muS, 0.0);
irr.b = trans.b * max(muS, 0.0);
irr.a = 1.0;
result.data[y * result.xsize + x] = irr;
}
}
return result;
}
/* nearest intersection of ray r,mu with ground or top atmosphere boundary
* mu=cos(ray zenith angle at ray origin) */
static double limit(double r, double mu)
{
double dout = -r * mu + sqrt(r * r * (mu * mu - 1.0) + RL * RL);
double delta2 = r * r * (mu * mu - 1.0) + Rg * Rg;
if (delta2 >= 0.0)
{
double din = -r * mu - sqrt(delta2);
if (din >= 0.0) {
dout = min(dout, din);
}
}
return dout;
}
static double _opticalDepthTransmittance(double H, double r, double mu)
{
double result = 0.0;
double dx = limit(r, mu) / (double)TRANSMITTANCE_INTEGRAL_SAMPLES;
double xi = 0.0;
double yi = exp(-(r - Rg) / H);
int i;
for (i = 1; i <= TRANSMITTANCE_INTEGRAL_SAMPLES; ++i) {
double xj = (double)i * dx;
double yj = exp(-(sqrt(r * r + xj * xj + 2.0 * xj * r * mu) - Rg) / H);
result += (yi + yj) / 2.0 * dx;
xi = xj;
yi = yj;
}
return mu < -sqrt(1.0 - (Rg / r) * (Rg / r)) ? 1e9 : result;
}
static void _getTransmittanceRMu(double x, double y, double* r, double* muS)
{
#ifdef TRANSMITTANCE_NON_LINEAR
*r = Rg + (y * y) * (Rt - Rg);
*muS = -0.15 + tan(1.5 * x) / tan(1.5) * (1.0 + 0.15);
#else
*r = Rg + y * (Rt - Rg);
*muS = -0.15 + x * (1.0 + 0.15);
#endif
}
static Color _debugSave2D(void* data, int x, int y)
{
Texture2D* tex = (Texture2D*)data;
return tex->data[y * tex->xsize + x];
}
static Texture2D _precomputeTransmittanceTexture()
{
Texture2D result;
int x, y;
result.xsize = 256;
result.ysize = 64;
result.data = malloc(sizeof(Color) * result.xsize * result.ysize); /* TODO free */
for (x = 0; x < result.xsize; x++)
{
for (y = 0; y < result.ysize; y++)
{
double r, muS;
_getTransmittanceRMu((double)x / result.xsize, (double)y / result.ysize, &r, &muS);
double depth1 = _opticalDepthTransmittance(HR, r, muS);
double depth2 = _opticalDepthTransmittance(HM, r, muS);
Color trans;
trans.r = exp(-(betaR.r * depth1 + betaMEx.x * depth2));
trans.g = exp(-(betaR.g * depth1 + betaMEx.y * depth2));
trans.b = exp(-(betaR.b * depth1 + betaMEx.z * depth2));
trans.a = 1.0;
result.data[y * result.xsize + x] = trans; /* Eq (5) */
}
}
return result;
}
void brunetonInit()
{
if (_transmittanceTexture.xsize == 0) /* TEMP */
{
_transmittanceTexture = _precomputeTransmittanceTexture();
_irrDeltaETexture = _precomputeIrrDeltaETexture();
//_inscatterSampler = _precomputeInscatterSampler();
}
/* DEBUG */
systemSavePictureFile("transmittance.png", _debugSave2D, &_transmittanceTexture, _transmittanceTexture.xsize, _transmittanceTexture.ysize);
systemSavePictureFile("irrdeltae.png", _debugSave2D, &_irrDeltaETexture, _irrDeltaETexture.xsize, _irrDeltaETexture.ysize);
exit(1);
}
/* transmittance(=transparency) of atmosphere for ray (r,mu) of length d
(mu=cos(view zenith angle)), intersections with ground ignored
uses analytic formula instead of transmittance texture */
static Vector3 _analyticTransmittance(double r, double mu, double d)
{
Vector3 result;
double opt = _opticalDepth(HR, r, mu, d);
result.x = exp(-betaR.r * opt) - betaMEx.x * opt;
result.y = exp(-betaR.g * opt) - betaMEx.y * opt;
result.z = exp(-betaR.b * opt) - betaMEx.z * opt;
return result;
}
static inline Color _applyInscatter(Color inscatter, Color attmod, Color samp)
{
inscatter.r = inscatter.r - attmod.r * samp.r;
inscatter.g = inscatter.g - attmod.g * samp.g;
inscatter.b = inscatter.b - attmod.b * samp.b;
inscatter.a = inscatter.a - attmod.a * samp.a;
return vec4max(inscatter, 0.0);
}
/* inscattered light along ray x+tv, when sun in direction s (=S[L]-T(x,x0)S[L]|x0) */
static Color _inscatter(Vector3* _x, double* _t, Vector3 v, Vector3 s, double* _r, double* _mu, Vector3* attenuation)
{
Color result;
double r = v3Norm(*_x);
double mu = v3Dot(*_x, v) / r;
double d = -r * mu - sqrt(r * r * (mu * mu - 1.0) + Rt * Rt);
if (d > 0.0)
{
/* if x in space and ray intersects atmosphere
move x to nearest intersection of ray with top atmosphere boundary */
_x->x += d * v.x;
_x->y += d * v.y;
_x->z += d * v.z;
*_t -= d;
mu = (r * mu + d) / Rt;
r = Rt;
}
double t = *_t;
Vector3 x = *_x;
if (r <= Rt)
{
/* if ray intersects atmosphere */
double nu = v3Dot(v, s);
double muS = v3Dot(x, s) / r;
double phaseR = _phaseFunctionR(nu);
double phaseM = _phaseFunctionM(nu);
Color inscatter = vec4max(_texture4D(&_inscatterSampler, r, mu, muS, nu), 0.0);
if (t > 0.0)
{
Vector3 x0 = v3Add(x, v3Scale(v, t));
double r0 = v3Norm(x0);
double rMu0 = v3Dot(x0, v);
double mu0 = rMu0 / r0;
double muS0 = v3Dot(x0, s) / r0;
#ifdef FIX
/* avoids imprecision problems in transmittance computations based on textures */
*attenuation = _analyticTransmittance(r, mu, t);
#else
*attenuation = _transmittance(r, mu, v, x0);
#endif
if (r0 > Rg + 0.01)
{
/* computes S[L]-T(x,x0)S[L]|x0 */
Color attmod = {attenuation->x, attenuation->y, attenuation->z, attenuation->x};
Color samp = _texture4D(&_inscatterSampler, r0, mu0, muS0, nu);
inscatter = _applyInscatter(inscatter, attmod, samp);
#ifdef FIX
/* avoids imprecision problems near horizon by interpolating between two points above and below horizon */
const double EPS = 0.004;
double muHoriz = -sqrt(1.0 - (Rg / r) * (Rg / r));
if (fabs(mu - muHoriz) < EPS)
{
double a = ((mu - muHoriz) + EPS) / (2.0 * EPS);
mu = muHoriz - EPS;
r0 = sqrt(r * r + t * t + 2.0 * r * t * mu);
mu0 = (r * mu + t) / r0;
Color inScatter0 = _texture4D(&_inscatterSampler, r, mu, muS, nu);
Color inScatter1 = _texture4D(&_inscatterSampler, r0, mu0, muS0, nu);
Color inScatterA = _applyInscatter(inScatter0, attmod, inScatter1);
mu = muHoriz + EPS;
r0 = sqrt(r * r + t * t + 2.0 * r * t * mu);
mu0 = (r * mu + t) / r0;
inScatter0 = _texture4D(&_inscatterSampler, r, mu, muS, nu);
inScatter1 = _texture4D(&_inscatterSampler, r0, mu0, muS0, nu);
Color inScatterB = _applyInscatter(inScatter0, attmod, inScatter1);
inscatter = vec4mix(inScatterA, inScatterB, a);
}
#endif
}
}
#ifdef FIX
/* avoids imprecision problems in Mie scattering when sun is below horizon */
inscatter.a *= smoothstep(0.00, 0.02, muS);
#endif
Color mie = getMie(inscatter);
result.r = inscatter.r * phaseR + mie.r * phaseM;
result.g = inscatter.g * phaseR + mie.g * phaseM;
result.b = inscatter.b * phaseR + mie.b * phaseM;
result.a = inscatter.a * phaseR + mie.a * phaseM;
_fixVec4Min(&result, 0.0);
}
else
{
/* x in space and ray looking in space */
result = COLOR_BLACK;
}
*_r = r;
*_mu = mu;
result.r *= ISun;
result.g *= ISun;
result.b *= ISun;
result.a = 1.0;
return result;
}
/*ground radiance at end of ray x+tv, when sun in direction s
*attenuated bewteen ground and viewer (=R[L0]+R[L*]) */
/*static Color _groundColor(Vector3 x, double t, Vector3 v, Vector3 s, double r, double mu, Color attenuation)
{
Color result;
if (t > 0.0)
{ // if ray hits ground surface
// ground reflectance at end of ray, x0
Vector3 x0 = v3Add(x, v3Scale(v, t));
float r0 = v3Norm(x0);
Vector3 n = v3Scale(x0, 1.0 / r0);
vec2 coords = vec2(atan(n.y, n.x), acos(n.z)) * vec2(0.5, 1.0) / M_PI + vec2(0.5, 0.0);
Color reflectance;
if (r0 > Rg + 0.01)
{
reflectance = vec4(0.4, 0.4, 0.4, 0.0);
}
else
{
reflectance = texture2D(reflectanceSampler, coords) * vec4(0.2, 0.2, 0.2, 1.0);
}
// direct sun light (radiance) reaching x0
float muS = v3Dot(n, s);
Color sunLight = _transmittanceWithShadow(r0, muS);
// precomputed sky light (irradiance) (=E[L*]) at x0
Color groundSkyLight = irradiance(irradianceSampler, r0, muS);
// light reflected at x0 (=(R[L0]+R[L*])/T(x,x0))
Color groundColor = reflectance.rgb * (max(muS, 0.0) * sunLight + groundSkyLight) * ISun / M_PI;
// water specular color due to sunLight
if (reflectance.w > 0.0)
{
vec3 h = normalize(s - v);
float fresnel = 0.02 + 0.98 * pow(1.0 - dot(-v, h), 5.0);
float waterBrdf = fresnel * pow(max(dot(h, n), 0.0), 150.0);
groundColor += reflectance.w * max(waterBrdf, 0.0) * sunLight * ISun;
}
result = attenuation * groundColor; //=R[L0]+R[L*]
}
else
{ // ray looking at the sky
return COLOR_BLACK;
}
return result;
}*/
/* transmittance(=transparency) of atmosphere for infinite ray (r,mu)
(mu=cos(view zenith angle)), or zero if ray intersects ground */
static Color _transmittanceWithShadow(double r, double mu)
{
return mu < -sqrt(1.0 - (Rg / r) * (Rg / r)) ? COLOR_BLACK : _transmittance(r, mu);
}
/* direct sun light for ray x+tv, when sun in direction s (=L0) */
static Color _sunColor(Vector3 x, double t, Vector3 v, Vector3 s, double r, double mu)
{
if (t > 0.0)
{
return COLOR_BLACK;
}
else
{
Color transmittance = r <= Rt ? _transmittanceWithShadow(r, mu) : COLOR_WHITE; // T(x,xo)
double isun = step(cos(M_PI / 180.0), v3Dot(v, s)) * ISun; // Lsun
transmittance.r *= isun;
transmittance.g *= isun;
transmittance.b *= isun;
transmittance.a *= isun;
return transmittance; // Eq (9)
}
}
static Color _hdr(Color c1, Color c2, Color c3)
{
Color L = {c1.r + c2.r + c3.r, c1.g + c2.g + c3.g, c1.b + c2.b + c3.b, 1.0};
L.r *= exposure;
L.g *= exposure;
L.b *= exposure;
L.a *= exposure;
L.r = L.r < 1.413 ? pow(L.r * 0.38317, 1.0 / 2.2) : 1.0 - exp(-L.r);
L.g = L.g < 1.413 ? pow(L.g * 0.38317, 1.0 / 2.2) : 1.0 - exp(-L.g);
L.b = L.b < 1.413 ? pow(L.b * 0.38317, 1.0 / 2.2) : 1.0 - exp(-L.b);
return L;
}
Color brunetonGetSkyColor(AtmosphereDefinition* definition, Vector3 eye, Vector3 direction, Vector3 sun_position)
{
Vector3 x = {0.0, Rg + eye.y, 0.0};
Vector3 v = v3Normalize(direction);
Vector3 s = v3Normalize(v3Sub(sun_position, eye));
double r = v3Norm(x);
double mu = v3Dot(x, v) / r;
double t = -r * mu - sqrt(r * r * (mu * mu - 1.0) + Rg * Rg);
Vector3 g = {0.0, 0.0, Rg + 10.0};
g = v3Sub(x, g);
double a = v.x * v.x + v.y * v.y - v.z * v.z;
double b = 2.0 * (g.x * v.x + g.y * v.y - g.z * v.z);
double c = g.x * g.x + g.y * g.y - g.z * g.z;
double d = -(b + sqrt(b * b - 4.0 * a * c)) / (2.0 * a);
int cone = d > 0.0 && fabs(x.z + d * v.z - Rg) <= 10.0;
if (t > 0.0)
{
if (cone && d < t)
{
t = d;
}
}
else if (cone)
{
t = d;
}
Vector3 attenuation;
Color inscatterColor = _inscatter(&x, &t, v, s, &r, &mu, &attenuation); //S[L]-T(x,xs)S[l]|xs
/*Color groundColor = _groundColor(x, t, v, s, r, mu, attenuation); //R[L0]+R[L*]*/
Color groundColor = COLOR_BLACK;
Color sunColor = _sunColor(x, t, v, s, r, mu); //L0
return _hdr(sunColor, groundColor, inscatterColor); // Eq (16)
}
#else
Color brunetonGetSkyColor(AtmosphereDefinition* definition, Vector3 eye, Vector3 direction, Vector3 sun_position)
{
return COLOR_BLACK;
}
#endif
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