paysages : Progress on bruneton atmospheric model (WIP).
git-svn-id: https://subversion.assembla.com/svn/thunderk/paysages@478 b1fd45b6-86a6-48da-8261-f70d1f35bdcc
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ThunderK
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983270ee56
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b765ae2cff
2 changed files with 159 additions and 85 deletions
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@ -19,13 +19,36 @@ static const double Rg = 6360.0;
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static const double Rt = 6420.0;
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static const double RL = 6421.0;
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static const double exposure = 0.4;
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static const float ISun = 100.0;
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static const double ISun = 100.0;
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#define RES_MU 128
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#define RES_MU_S 32
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#define RES_R 32
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#define RES_NU 8
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#define TRANSMITTANCE_INTEGRAL_SAMPLES 500
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/*#define SKY_W 64
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#define SKY_H 16*/
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#define SKY_W 640
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#define SKY_H 160
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typedef struct
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{
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int xsize;
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int ysize;
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Color* data;
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} Texture2D;
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typedef struct
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{
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int xsize;
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int ysize;
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int zsize;
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Color* data;
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} Texture3D;
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Texture2D _transmittanceTexture = {0, 0, 0};
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Texture2D _irrDeltaETexture;
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Texture3D _inscatterSampler;
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// Rayleigh
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static const double HR = 8.0;
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@ -49,8 +72,8 @@ static const vec3 betaMEx = betaMSca / 0.9;
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static const float mieG = 0.65;*/
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#define step(_a_,_b_) ((_a_) < (_b_) ? 0 : 1)
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#define max(_a_,_b_) ((_a_) < (_b_) ? (_a_) : (_b_))
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#define min(_a_,_b_) ((_a_) > (_b_) ? (_a_) : (_b_))
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#define max(_a_,_b_) ((_a_) > (_b_) ? (_a_) : (_b_))
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#define min(_a_,_b_) ((_a_) < (_b_) ? (_a_) : (_b_))
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#define sign(_a_) ((_a_) < 0.0 ? -1.0 : ((_a_) > 0.0 ? 1.0 : 0.0))
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#define mix(_x_,_y_,_a_) ((_x_) * (1.0 - (_a_)) + (_y_) * (_a_))
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static inline Color vec4mix(Color v1, Color v2, double a)
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@ -109,20 +132,48 @@ static inline Color vec4(double r, double g, double b, double a)
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return result;
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}
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typedef struct
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static Color _texture2D(Texture2D* tex, double x, double y)
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{
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int xsize;
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int ysize;
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Color* data;
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} Texture2D;
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if (x < 0.0) x = 0.0;
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if (x > 1.0) x = 1.0;
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if (y < 0.0) y = 0.0;
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if (y > 1.0) y = 1.0;
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/* TODO Interpolation */
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int ix = (int)round(x * ((double)(tex->xsize - 1)) + 0.5);
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int iy = (int)round(y * ((double)(tex->ysize - 1)) + 0.5);
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return tex->data[iy * tex->xsize + ix];
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}
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typedef struct
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static Color _texture3D(Texture3D* tex, Vector3 p)
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{
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int xsize;
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int ysize;
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int zsize;
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Color* data;
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} Texture3D;
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/* TODO Interpolation */
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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))];
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}
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static Color _texture4D(Texture3D* tex3d, double r, double mu, double muS, double nu)
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{
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double H = sqrt(Rt * Rt - Rg * Rg);
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double rho = sqrt(r * r - Rg * Rg);
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#ifdef INSCATTER_NON_LINEAR
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double rmu = r * mu;
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double delta = rmu * rmu - r * r + Rg * Rg;
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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));
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double uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
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double uMu = cst.a + (rmu * cst.r + sqrt(delta + cst.g)) / (rho + cst.b) * (0.5 - 1.0 / (double)(RES_MU));
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// paper formula
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//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));
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// better formula
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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));
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#else
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float uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
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float uMu = 0.5 / (double)(RES_MU) + (mu + 1.0) / 2.0 * (1.0 - 1.0 / (double)(RES_MU));
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float uMuS = 0.5 / (double)(RES_MU_S) + max(muS + 0.2, 0.0) / 1.2 * (1.0 - 1.0 / (double)(RES_MU_S));
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#endif
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double lerp = (nu + 1.0) / 2.0 * ((double)(RES_NU) - 1.0);
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double uNu = floor(lerp);
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lerp = lerp - uNu;
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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);
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}
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/* Rayleigh phase function */
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static double _phaseFunctionR(double mu)
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@ -170,15 +221,92 @@ static double _opticalDepth(double H, double r, double mu, double d)
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static Texture3D _precomputeInscatterSampler()
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{
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Texture3D result;
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int x, y;
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result.xsize = 0;
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result.ysize = 0;
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result.zsize = 0;
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result.data = 0;
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#if 0
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result.xsize = 256;
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result.ysize = 64;
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result.data = malloc(sizeof(Color) * result.xsize * result.ysize); /* TODO free */
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for (x = 0; x < result.xsize; x++)
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{
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for (y = 0; y < result.ysize; y++)
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{
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double r, muS;
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_getTransmittanceRMu((double)x / result.xsize, (double)y / result.ysize, &r, &muS);
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double depth1 = _opticalDepthTransmittance(HR, r, muS);
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double depth2 = _opticalDepthTransmittance(HM, r, muS);
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Color trans;
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trans.r = exp(-(betaR.r * depth1 + betaMEx.x * depth2));
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trans.g = exp(-(betaR.g * depth1 + betaMEx.y * depth2));
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trans.b = exp(-(betaR.b * depth1 + betaMEx.z * depth2));
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trans.a = 1.0;
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result.data[y * result.xsize + x] = trans; /* Eq (5) */
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}
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}
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#endif
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return result;
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}
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static inline void _getTransmittanceUV(double r, double mu, double* u, double* v)
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{
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#ifdef TRANSMITTANCE_NON_LINEAR
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*v = sqrt((r - Rg) / (Rt - Rg));
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*u = atan((mu + 0.15) / (1.0 + 0.15) * tan(1.5)) / 1.5;
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#else
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*v = (r - Rg) / (Rt - Rg);
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*u = (mu + 0.15) / (1.0 + 0.15);
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#endif
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}
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/* transmittance(=transparency) of atmosphere for infinite ray (r,mu)
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(mu=cos(view zenith angle)), intersections with ground ignored */
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static Color _transmittance(double r, double mu)
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{
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double u, v;
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_getTransmittanceUV(r, mu, &u, &v);
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return _texture2D(&_transmittanceTexture, u, v);
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}
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static void _getIrradianceRMuS(double x, double y, double* r, double* muS)
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{
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*r = Rg + y * (Rt - Rg);
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*muS = -0.2 + x * (1.0 + 0.2);
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}
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static Texture2D _precomputeIrrDeltaETexture()
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{
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Texture2D result;
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int x, y;
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result.xsize = SKY_W;
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result.ysize = SKY_H;
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result.data = malloc(sizeof(Color) * result.xsize * result.ysize); /* TODO free */
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/* Irradiance program */
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for (x = 0; x < result.xsize; x++)
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{
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for (y = 0; y < result.ysize; y++)
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{
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double r, muS, u, v;
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Color trans, irr;
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_getIrradianceRMuS((double)x / result.xsize, (double)y / result.ysize, &r, &muS);
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trans = _transmittance(r, muS);
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_getTransmittanceUV(r, muS, &u, &v);
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//printf("%d %d -> %f %f -> %f %f %f\n", x, y, u, v, trans.r, trans.g, trans.b);
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irr.r = trans.r * max(muS, 0.0);
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irr.g = trans.g * max(muS, 0.0);
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irr.b = trans.b * max(muS, 0.0);
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irr.a = 1.0;
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result.data[y * result.xsize + x] = irr;
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}
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}
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return result;
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}
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Texture3D _inscatterSampler;
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/* nearest intersection of ray r,mu with ground or top atmosphere boundary
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* mu=cos(ray zenith angle at ray origin) */
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@ -188,7 +316,7 @@ static double limit(double r, double mu)
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double delta2 = r * r * (mu * mu - 1.0) + Rg * Rg;
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if (delta2 >= 0.0)
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{
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float din = -r * mu - sqrt(delta2);
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double din = -r * mu - sqrt(delta2);
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if (din >= 0.0) {
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dout = min(dout, din);
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}
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@ -230,7 +358,7 @@ static Color _debugSave2D(void* data, int x, int y)
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return tex->data[y * tex->xsize + x];
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}
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static Texture2D _precomputeTransmittanceSampler()
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static Texture2D _precomputeTransmittanceTexture()
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{
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Texture2D result;
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int x, y;
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@ -256,58 +384,24 @@ static Texture2D _precomputeTransmittanceSampler()
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}
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}
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/* DEBUG */
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systemSavePictureFile("debug.png", _debugSave2D, &result, result.xsize, result.ysize);
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return result;
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}
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Texture2D _transmittanceSampler;
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void brunetonInit()
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{
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_inscatterSampler = _precomputeInscatterSampler();
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_transmittanceSampler = _precomputeTransmittanceSampler();
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if (_transmittanceTexture.xsize == 0) /* TEMP */
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{
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_transmittanceTexture = _precomputeTransmittanceTexture();
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_irrDeltaETexture = _precomputeIrrDeltaETexture();
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//_inscatterSampler = _precomputeInscatterSampler();
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}
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/* DEBUG */
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systemSavePictureFile("transmittance.png", _debugSave2D, &_transmittanceTexture, _transmittanceTexture.xsize, _transmittanceTexture.ysize);
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systemSavePictureFile("irrdeltae.png", _debugSave2D, &_irrDeltaETexture, _irrDeltaETexture.xsize, _irrDeltaETexture.ysize);
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exit(1);
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}
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static Color _texture2D(Texture2D* tex, double x, double y)
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{
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/* TODO Sampling */
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return COLOR_BLACK;
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}
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static Color _texture3D(Texture3D* tex, Vector3 location)
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{
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/* TODO Sampling */
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return COLOR_BLACK;
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}
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static Color _texture4D(Texture3D* tex3d, double r, double mu, double muS, double nu)
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{
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double H = sqrt(Rt * Rt - Rg * Rg);
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double rho = sqrt(r * r - Rg * Rg);
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#ifdef INSCATTER_NON_LINEAR
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double rmu = r * mu;
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double delta = rmu * rmu - r * r + Rg * Rg;
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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));
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double uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
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double uMu = cst.a + (rmu * cst.r + sqrt(delta + cst.g)) / (rho + cst.b) * (0.5 - 1.0 / (double)(RES_MU));
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// paper formula
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//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));
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// better formula
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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));
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#else
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float uR = 0.5 / (double)(RES_R) + rho / H * (1.0 - 1.0 / (double)(RES_R));
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float uMu = 0.5 / (double)(RES_MU) + (mu + 1.0) / 2.0 * (1.0 - 1.0 / (double)(RES_MU));
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float uMuS = 0.5 / (double)(RES_MU_S) + max(muS + 0.2, 0.0) / 1.2 * (1.0 - 1.0 / (double)(RES_MU_S));
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#endif
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double lerp = (nu + 1.0) / 2.0 * ((double)(RES_NU) - 1.0);
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double uNu = floor(lerp);
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lerp = lerp - uNu;
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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);
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}
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/* transmittance(=transparency) of atmosphere for ray (r,mu) of length d
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(mu=cos(view zenith angle)), intersections with ground ignored
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uses analytic formula instead of transmittance texture */
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@ -483,26 +577,6 @@ static Color _inscatter(Vector3* _x, double* _t, Vector3 v, Vector3 s, double* _
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return result;
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}*/
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static inline void _getTransmittanceUV(double r, double mu, double* u, double* v)
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{
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#ifdef TRANSMITTANCE_NON_LINEAR
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*v = sqrt((r - Rg) / (Rt - Rg));
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*u = atan((mu + 0.15) / (1.0 + 0.15) * tan(1.5)) / 1.5;
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#else
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*v = (r - Rg) / (Rt - Rg);
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*u = (mu + 0.15) / (1.0 + 0.15);
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#endif
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}
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/* transmittance(=transparency) of atmosphere for infinite ray (r,mu)
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(mu=cos(view zenith angle)), intersections with ground ignored */
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static Color _transmittance(double r, double mu)
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{
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double u, v;
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_getTransmittanceUV(r, mu, &u, &v);
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return _texture2D(&_transmittanceSampler, u, v);
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}
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/* transmittance(=transparency) of atmosphere for infinite ray (r,mu)
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(mu=cos(view zenith angle)), or zero if ray intersects ground */
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static Color _transmittanceWithShadow(double r, double mu)
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