diff options
Diffstat (limited to 'intern/cycles/kernel/closure/bsdf_microfacet.h')
| -rw-r--r-- | intern/cycles/kernel/closure/bsdf_microfacet.h | 50 |
1 files changed, 43 insertions, 7 deletions
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h index 38364bb1026..81ecfd0ebd3 100644 --- a/intern/cycles/kernel/closure/bsdf_microfacet.h +++ b/intern/cycles/kernel/closure/bsdf_microfacet.h @@ -370,6 +370,18 @@ ccl_device int bsdf_microfacet_ggx_refraction_setup(MicrofacetBsdf *bsdf) return SD_BSDF|SD_BSDF_HAS_EVAL; } +ccl_device int bsdf_microfacet_ggx_refraction_thin_setup(MicrofacetBsdf *bsdf) +{ + bsdf->extra = NULL; + + bsdf->alpha_x = saturate(bsdf->alpha_x); + bsdf->alpha_y = bsdf->alpha_x; + + bsdf->type = CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID; + + return SD_BSDF|SD_BSDF_HAS_EVAL; +} + ccl_device void bsdf_microfacet_ggx_blur(ShaderClosure *sc, float roughness) { MicrofacetBsdf *bsdf = (MicrofacetBsdf*)sc; @@ -383,7 +395,7 @@ ccl_device float3 bsdf_microfacet_ggx_eval_reflect(const ShaderClosure *sc, cons const MicrofacetBsdf *bsdf = (const MicrofacetBsdf*)sc; float alpha_x = bsdf->alpha_x; float alpha_y = bsdf->alpha_y; - bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID || bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID; float3 N = bsdf->N; if(m_refractive || alpha_x*alpha_y <= 1e-7f) @@ -494,7 +506,7 @@ ccl_device float3 bsdf_microfacet_ggx_eval_transmit(const ShaderClosure *sc, con float alpha_x = bsdf->alpha_x; float alpha_y = bsdf->alpha_y; float m_eta = bsdf->ior; - bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID || bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID; float3 N = bsdf->N; if(!m_refractive || alpha_x*alpha_y <= 1e-7f) @@ -507,7 +519,15 @@ ccl_device float3 bsdf_microfacet_ggx_eval_transmit(const ShaderClosure *sc, con return make_float3(0.0f, 0.0f, 0.0f); /* vectors on same side -- not possible */ /* compute half-vector of the refraction (eq. 16) */ - float3 ht = -(m_eta * omega_in + I); + float3 ht; + if(bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID) { + /* for thin surfaces refraction approximately cancels and thus specular transmission is modelled + * using a microfacet distribution which is simply reflected to the other side */ + ht = -(omega_in + I); + } + else { + ht = -(m_eta * omega_in + I); + } float3 Ht = normalize(ht); float cosHO = dot(Ht, I); float cosHI = dot(Ht, omega_in); @@ -536,7 +556,13 @@ ccl_device float3 bsdf_microfacet_ggx_eval_transmit(const ShaderClosure *sc, con /* out = fabsf(cosHI * cosHO) * (m_eta * m_eta) * G * D / (cosNO * Ht2) * pdf = pm * (m_eta * m_eta) * fabsf(cosHI) / Ht2 */ - float common = D * (m_eta * m_eta) / (cosNO * Ht2); + float common; + if(bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID) { + common = D * 0.25f / cosNO; + } + else { + common = D * (m_eta * m_eta) / (cosNO * Ht2); + } float out = G * fabsf(cosHI * cosHO) * common; *pdf = G1o * fabsf(cosHO * cosHI) * common; @@ -548,7 +574,7 @@ ccl_device int bsdf_microfacet_ggx_sample(KernelGlobals *kg, const ShaderClosure const MicrofacetBsdf *bsdf = (const MicrofacetBsdf*)sc; float alpha_x = bsdf->alpha_x; float alpha_y = bsdf->alpha_y; - bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + bool m_refractive = bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID || bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID; float3 N = bsdf->N; float cosNO = dot(N, I); @@ -686,6 +712,10 @@ ccl_device int bsdf_microfacet_ggx_sample(KernelGlobals *kg, const ShaderClosure float m_eta = bsdf->ior, fresnel; bool inside; + if(bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID) { + m_eta = 1.0f; + } + fresnel = fresnel_dielectric(m_eta, m, I, &R, &T, #ifdef __RAY_DIFFERENTIALS__ dIdx, dIdy, &dRdx, &dRdy, &dTdx, &dTdy, @@ -1055,7 +1085,7 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl *domega_in_dy = dTdy; #endif - if(alpha_x*alpha_y <= 1e-7f || fabsf(m_eta - 1.0f) < 1e-4f) { + if(alpha_x*alpha_y <= 1e-7f || (fabsf(m_eta - 1.0f) < 1e-4f && bsdf->type != CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID)) { /* some high number for MIS */ *pdf = 1e6f; *eval = make_float3(1e6f, 1e6f, 1e6f); @@ -1082,7 +1112,13 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl Ht2 *= Ht2; /* see eval function for derivation */ - float common = D * (m_eta * m_eta) / (cosNO * Ht2); + float common; + if(bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_THIN_ID) { + common = D * 0.25f / cosNO; + } + else { + common = D * (m_eta * m_eta) / (cosNO * Ht2); + } float out = G * fabsf(cosHI * cosHO) * common; *pdf = G1o * cosHO * fabsf(cosHI) * common; |