diff options
Diffstat (limited to 'intern/cycles/kernel/closure/bsdf_microfacet.h')
| -rw-r--r-- | intern/cycles/kernel/closure/bsdf_microfacet.h | 79 |
1 files changed, 39 insertions, 40 deletions
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h index aa21633070a..7bf7c2806d4 100644 --- a/intern/cycles/kernel/closure/bsdf_microfacet.h +++ b/intern/cycles/kernel/closure/bsdf_microfacet.h @@ -615,6 +615,36 @@ ccl_device void bsdf_microfacet_beckmann_blur(ShaderClosure *sc, float roughness sc->data1 = fmaxf(roughness, sc->data1); /* alpha_y */ } +ccl_device_inline float bsdf_beckmann_G1(float alpha, float cos_n) +{ + cos_n *= cos_n; + float invA = alpha * safe_sqrtf((1.0f - cos_n) / cos_n); + if(invA < 0.625f) { + return 1.0f; + } + + float a = 1.0f / invA; + return ((2.181f*a + 3.535f)*a) / ((2.577f*a + 2.276f)*a + 1.0f); +} + +ccl_device_inline float bsdf_beckmann_aniso_G1(float alpha_x, float alpha_y, float cos_n, float cos_phi, float sin_phi) +{ + cos_n *= cos_n; + sin_phi *= sin_phi; + cos_phi *= cos_phi; + alpha_x *= alpha_x; + alpha_y *= alpha_y; + + float alphaO2 = (cos_phi*alpha_x + sin_phi*alpha_y) / (cos_phi + sin_phi); + float invA = safe_sqrtf(alphaO2 * (1 - cos_n) / cos_n); + if(invA < 0.625f) { + return 1.0f; + } + + float a = 1.0f / invA; + return ((2.181f*a + 3.535f)*a) / ((2.577f*a + 2.276f)*a + 1.0f); +} + ccl_device float3 bsdf_microfacet_beckmann_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf) { float alpha_x = sc->data0; @@ -646,10 +676,8 @@ ccl_device float3 bsdf_microfacet_beckmann_eval_reflect(const ShaderClosure *sc, D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4); /* eq. 26, 27: now calculate G1(i,m) and G1(o,m) */ - float ao = 1 / (alpha_x * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO))); - float ai = 1 / (alpha_x * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI))); - G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f; - G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + G1o = bsdf_beckmann_G1(alpha_x, cosNO); + G1i = bsdf_beckmann_G1(alpha_x, cosNI); } else { /* anisotropic */ @@ -668,24 +696,8 @@ ccl_device float3 bsdf_microfacet_beckmann_eval_reflect(const ShaderClosure *sc, D = expf(-slope_x*slope_x - slope_y*slope_y) / (M_PI_F * alpha2 * cosThetaM4); /* G1(i,m) and G1(o,m) */ - float tanThetaO2 = (1 - cosNO * cosNO) / (cosNO * cosNO); - float cosPhiO = dot(I, X); - float sinPhiO = dot(I, Y); - - float alphaO2 = (cosPhiO*cosPhiO)*(alpha_x*alpha_x) + (sinPhiO*sinPhiO)*(alpha_y*alpha_y); - alphaO2 /= cosPhiO*cosPhiO + sinPhiO*sinPhiO; - - float tanThetaI2 = (1 - cosNI * cosNI) / (cosNI * cosNI); - float cosPhiI = dot(omega_in, X); - float sinPhiI = dot(omega_in, Y); - - float alphaI2 = (cosPhiI*cosPhiI)*(alpha_x*alpha_x) + (sinPhiI*sinPhiI)*(alpha_y*alpha_y); - alphaI2 /= cosPhiI*cosPhiI + sinPhiI*sinPhiI; - - float ao = 1 / (safe_sqrtf(alphaO2 * tanThetaO2)); - float ai = 1 / (safe_sqrtf(alphaI2 * tanThetaI2)); - G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f; - G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + G1o = bsdf_beckmann_aniso_G1(alpha_x, alpha_y, cosNO, dot(I, X), dot(I, Y)); + G1i = bsdf_beckmann_aniso_G1(alpha_x, alpha_y, cosNI, dot(omega_in, X), dot(omega_in, Y)); } float G = G1o * G1i; @@ -740,10 +752,8 @@ ccl_device float3 bsdf_microfacet_beckmann_eval_transmit(const ShaderClosure *sc float D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4); /* eq. 26, 27: now calculate G1(i,m) and G1(o,m) */ - float ao = 1 / (alpha_x * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO))); - float ai = 1 / (alpha_x * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI))); - float G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f; - float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + float G1o = bsdf_beckmann_G1(alpha_x, cosNO); + float G1i = bsdf_beckmann_G1(alpha_x, cosNI); float G = G1o * G1i; /* probability */ @@ -820,8 +830,7 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl float cosNI = dot(N, *omega_in); /* eq. 26, 27: now calculate G1(i,m) */ - float ai = 1 / (alpha_x * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI))); - G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + G1i = bsdf_beckmann_G1(alpha_x, cosNI); } else { /* anisotropic distribution */ @@ -836,16 +845,7 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl D = expf(-slope_x*slope_x - slope_y*slope_y) / (M_PI_F * alpha2 * cosThetaM4); /* G1(i,m) */ - float cosNI = dot(N, *omega_in); - float tanThetaI2 = (1 - cosNI * cosNI) / (cosNI * cosNI); - float cosPhiI = dot(*omega_in, X); - float sinPhiI = dot(*omega_in, Y); - - float alphaI2 = (cosPhiI*cosPhiI)*(alpha_x*alpha_x) + (sinPhiI*sinPhiI)*(alpha_y*alpha_y); - alphaI2 /= cosPhiI*cosPhiI + sinPhiI*sinPhiI; - - float ai = 1 / (safe_sqrtf(alphaI2 * tanThetaI2)); - G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + G1i = bsdf_beckmann_aniso_G1(alpha_x, alpha_y, dot(*omega_in, N), dot(*omega_in, X), dot(*omega_in, Y)); } float G = G1o * G1i; @@ -906,8 +906,7 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl float cosNI = dot(N, *omega_in); /* eq. 26, 27: now calculate G1(i,m) */ - float ai = 1 / (alpha_x * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI))); - float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f; + float G1i = bsdf_beckmann_G1(alpha_x, cosNI); float G = G1o * G1i; /* eq. 21 */ |