diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_subsurface.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_subsurface.h | 520 |
1 files changed, 293 insertions, 227 deletions
diff --git a/intern/cycles/kernel/kernel_subsurface.h b/intern/cycles/kernel/kernel_subsurface.h index 52c05b85aee..e8553d84547 100644 --- a/intern/cycles/kernel/kernel_subsurface.h +++ b/intern/cycles/kernel/kernel_subsurface.h @@ -20,134 +20,82 @@ CCL_NAMESPACE_BEGIN * * BSSRDF Importance Sampling, SIGGRAPH 2013 * http://library.imageworks.com/pdfs/imageworks-library-BSSRDF-sampling.pdf - * - */ - -/* TODO: - * - test using power heuristic for combing bssrdfs - * - try to reduce one sample model variance */ -#define BSSRDF_MULTI_EVAL - -ccl_device ShaderClosure *subsurface_scatter_pick_closure(KernelGlobals *kg, ShaderData *sd, float *probability) -{ - /* sum sample weights of bssrdf and bsdf */ - float bsdf_sum = 0.0f; - float bssrdf_sum = 0.0f; - - for(int i = 0; i < sd->num_closure; i++) { - ShaderClosure *sc = &sd->closure[i]; - - if(CLOSURE_IS_BSDF(sc->type)) - bsdf_sum += sc->sample_weight; - else if(CLOSURE_IS_BSSRDF(sc->type)) - bssrdf_sum += sc->sample_weight; - } - - /* use bsdf or bssrdf? */ - float r = sd->randb_closure*(bsdf_sum + bssrdf_sum); - - if(r < bsdf_sum) { - /* use bsdf, and adjust randb so we can reuse it for picking a bsdf */ - sd->randb_closure = r/bsdf_sum; - *probability = (bsdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/bsdf_sum: 1.0f; - return NULL; - } - - /* use bssrdf */ - r -= bsdf_sum; - - float sum = 0.0f; - - for(int i = 0; i < sd->num_closure; i++) { - ShaderClosure *sc = &sd->closure[i]; - - if(CLOSURE_IS_BSSRDF(sc->type)) { - sum += sc->sample_weight; - - if(r <= sum) { - sd->randb_closure = (r - (sum - sc->sample_weight))/sc->sample_weight; - -#ifdef BSSRDF_MULTI_EVAL - *probability = (bssrdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/bssrdf_sum: 1.0f; -#else - *probability = (bssrdf_sum > 0.0f)? (bsdf_sum + bssrdf_sum)/sc->sample_weight: 1.0f; -#endif - return sc; - } - } - } - - /* should never happen */ - sd->randb_closure = 0.0f; - *probability = 1.0f; - return NULL; -} - ccl_device_inline float3 subsurface_scatter_eval(ShaderData *sd, - ShaderClosure *sc, + const ShaderClosure *sc, float disk_r, float r, bool all) { -#ifdef BSSRDF_MULTI_EVAL /* this is the veach one-sample model with balance heuristic, some pdf * factors drop out when using balance heuristic weighting */ float3 eval_sum = make_float3(0.0f, 0.0f, 0.0f); float pdf_sum = 0.0f; - float sample_weight_sum = 0.0f; - int num_bssrdf = 0; + float sample_weight_inv = 0.0f; - for(int i = 0; i < sd->num_closure; i++) { - sc = &sd->closure[i]; - - if(CLOSURE_IS_BSSRDF(sc->type)) { - float sample_weight = (all)? 1.0f: sc->sample_weight; - sample_weight_sum += sample_weight; + if(!all) { + float sample_weight_sum = 0.0f; + + for(int i = 0; i < sd->num_closure; i++) { + sc = &sd->closure[i]; + + if(CLOSURE_IS_DISK_BSSRDF(sc->type)) { + sample_weight_sum += sc->sample_weight; + } } - } - float sample_weight_inv = 1.0f/sample_weight_sum; + sample_weight_inv = 1.0f/sample_weight_sum; + } for(int i = 0; i < sd->num_closure; i++) { sc = &sd->closure[i]; - if(CLOSURE_IS_BSSRDF(sc->type)) { + if(CLOSURE_IS_DISK_BSSRDF(sc->type)) { /* in case of branched path integrate we sample all bssrdf's once, * for path trace we pick one, so adjust pdf for that */ float sample_weight = (all)? 1.0f: sc->sample_weight * sample_weight_inv; /* compute pdf */ - float pdf = bssrdf_pdf(sc, r); - float disk_pdf = bssrdf_pdf(sc, disk_r); + float3 eval = bssrdf_eval(sc, r); + float pdf = bssrdf_pdf(sc, disk_r); - /* TODO power heuristic is not working correct here */ - eval_sum += sc->weight*pdf; //*sample_weight*disk_pdf; - pdf_sum += sample_weight*disk_pdf; //*sample_weight*disk_pdf; - - num_bssrdf++; + eval_sum += sc->weight * eval; + pdf_sum += sample_weight * pdf; } } return (pdf_sum > 0.0f)? eval_sum / pdf_sum : make_float3(0.0f, 0.0f, 0.0f); -#else - float pdf = bssrdf_pdf(pick_sc, r); - float disk_pdf = bssrdf_pdf(pick_sc, disk_r); - - return pick_sc->weight * pdf / disk_pdf; -#endif } /* replace closures with a single diffuse bsdf closure after scatter step */ -ccl_device void subsurface_scatter_setup_diffuse_bsdf(ShaderData *sd, float3 weight, bool hit, float3 N) +ccl_device void subsurface_scatter_setup_diffuse_bsdf(KernelGlobals *kg, ShaderData *sd, const ShaderClosure *sc, float3 weight, float3 N) { sd->flag &= ~SD_CLOSURE_FLAGS; - sd->randb_closure = 0.0f; sd->num_closure = 0; - sd->num_closure_extra = 0; + sd->num_closure_left = kernel_data.integrator.max_closures; + + Bssrdf *bssrdf = (Bssrdf *)sc; +#ifdef __PRINCIPLED__ + if(bssrdf->type == CLOSURE_BSSRDF_PRINCIPLED_ID || + bssrdf->type == CLOSURE_BSSRDF_PRINCIPLED_RANDOM_WALK_ID) + { + PrincipledDiffuseBsdf *bsdf = (PrincipledDiffuseBsdf*)bsdf_alloc(sd, sizeof(PrincipledDiffuseBsdf), weight); + + if(bsdf) { + bsdf->N = N; + bsdf->roughness = bssrdf->roughness; + sd->flag |= bsdf_principled_diffuse_setup(bsdf); - if(hit) { + /* replace CLOSURE_BSDF_PRINCIPLED_DIFFUSE_ID with this special ID so render passes + * can recognize it as not being a regular Disney principled diffuse closure */ + bsdf->type = CLOSURE_BSDF_BSSRDF_PRINCIPLED_ID; + } + } + else if(CLOSURE_IS_BSDF_BSSRDF(bssrdf->type) || + CLOSURE_IS_BSSRDF(bssrdf->type)) +#endif /* __PRINCIPLED__ */ + { DiffuseBsdf *bsdf = (DiffuseBsdf*)bsdf_alloc(sd, sizeof(DiffuseBsdf), weight); if(bsdf) { @@ -185,8 +133,7 @@ ccl_device float3 subsurface_color_pow(float3 color, float exponent) ccl_device void subsurface_color_bump_blur(KernelGlobals *kg, ShaderData *sd, - PathState *state, - int state_flag, + ccl_addr_space PathState *state, float3 *eval, float3 *N) { @@ -199,7 +146,7 @@ ccl_device void subsurface_color_bump_blur(KernelGlobals *kg, if(bump || texture_blur > 0.0f) { /* average color and normal at incoming point */ - shader_eval_surface(kg, sd, NULL, state, 0.0f, state_flag, SHADER_CONTEXT_SSS); + shader_eval_surface(kg, sd, state, state->flag); float3 in_color = shader_bssrdf_sum(sd, (bump)? N: NULL, NULL); /* we simply divide out the average color and multiply with the average @@ -218,11 +165,11 @@ ccl_device void subsurface_color_bump_blur(KernelGlobals *kg, /* Subsurface scattering step, from a point on the surface to other * nearby points on the same object. */ -ccl_device_inline int subsurface_scatter_multi_intersect( +ccl_device_inline int subsurface_scatter_disk( KernelGlobals *kg, - SubsurfaceIntersection *ss_isect, + LocalIntersection *ss_isect, ShaderData *sd, - ShaderClosure *sc, + const ShaderClosure *sc, uint *lcg_state, float disk_u, float disk_v, @@ -235,26 +182,20 @@ ccl_device_inline int subsurface_scatter_multi_intersect( disk_N = sd->Ng; make_orthonormals(disk_N, &disk_T, &disk_B); - /* reusing variable for picking the closure gives a bit nicer stratification - * for path tracer, for branched we do all closures so it doesn't help */ - float axisu = (all)? disk_u: sd->randb_closure; - - if(axisu < 0.5f) { + if(disk_v < 0.5f) { pick_pdf_N = 0.5f; pick_pdf_T = 0.25f; pick_pdf_B = 0.25f; - if(all) - disk_u *= 2.0f; + disk_v *= 2.0f; } - else if(axisu < 0.75f) { + else if(disk_v < 0.75f) { float3 tmp = disk_N; disk_N = disk_T; disk_T = tmp; pick_pdf_N = 0.25f; pick_pdf_T = 0.5f; pick_pdf_B = 0.25f; - if(all) - disk_u = (disk_u - 0.5f)*4.0f; + disk_v = (disk_v - 0.5f)*4.0f; } else { float3 tmp = disk_N; @@ -263,21 +204,24 @@ ccl_device_inline int subsurface_scatter_multi_intersect( pick_pdf_N = 0.25f; pick_pdf_T = 0.25f; pick_pdf_B = 0.5f; - if(all) - disk_u = (disk_u - 0.75f)*4.0f; + disk_v = (disk_v - 0.75f)*4.0f; } /* sample point on disk */ - float phi = M_2PI_F * disk_u; - float disk_r = disk_v; - float disk_height; + float phi = M_2PI_F * disk_v; + float disk_height, disk_r; - bssrdf_sample(sc, disk_r, &disk_r, &disk_height); + bssrdf_sample(sc, disk_u, &disk_r, &disk_height); float3 disk_P = (disk_r*cosf(phi)) * disk_T + (disk_r*sinf(phi)) * disk_B; /* create ray */ +#ifdef __SPLIT_KERNEL__ + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; +#else Ray *ray = &ss_isect->ray; +#endif ray->P = sd->P + disk_N*disk_height + disk_P; ray->D = -disk_N; ray->t = 2.0f*disk_height; @@ -287,37 +231,37 @@ ccl_device_inline int subsurface_scatter_multi_intersect( /* intersect with the same object. if multiple intersections are found it * will use at most BSSRDF_MAX_HITS hits, a random subset of all hits */ - scene_intersect_subsurface(kg, - ray, - ss_isect, - sd->object, - lcg_state, - BSSRDF_MAX_HITS); + scene_intersect_local(kg, + *ray, + ss_isect, + sd->object, + lcg_state, + BSSRDF_MAX_HITS); int num_eval_hits = min(ss_isect->num_hits, BSSRDF_MAX_HITS); for(int hit = 0; hit < num_eval_hits; hit++) { /* Quickly retrieve P and Ng without setting up ShaderData. */ float3 hit_P; - if(ccl_fetch(sd, type) & PRIMITIVE_TRIANGLE) { - hit_P = triangle_refine_subsurface(kg, - sd, - &ss_isect->hits[hit], - ray); + if(sd->type & PRIMITIVE_TRIANGLE) { + hit_P = triangle_refine_local(kg, + sd, + &ss_isect->hits[hit], + ray); } #ifdef __OBJECT_MOTION__ - else if(ccl_fetch(sd, type) & PRIMITIVE_MOTION_TRIANGLE) { + else if(sd->type & PRIMITIVE_MOTION_TRIANGLE) { float3 verts[3]; motion_triangle_vertices( kg, - ccl_fetch(sd, object), + sd->object, kernel_tex_fetch(__prim_index, ss_isect->hits[hit].prim), - ccl_fetch(sd, time), + sd->time, verts); - hit_P = motion_triangle_refine_subsurface(kg, - sd, - &ss_isect->hits[hit], - ray, - verts); + hit_P = motion_triangle_refine_local(kg, + sd, + &ss_isect->hits[hit], + ray, + verts); } #endif /* __OBJECT_MOTION__ */ else { @@ -330,140 +274,262 @@ ccl_device_inline int subsurface_scatter_multi_intersect( object_normal_transform(kg, sd, &hit_Ng); } - /* probability densities for local frame axes */ + /* Probability densities for local frame axes. */ float pdf_N = pick_pdf_N * fabsf(dot(disk_N, hit_Ng)); float pdf_T = pick_pdf_T * fabsf(dot(disk_T, hit_Ng)); float pdf_B = pick_pdf_B * fabsf(dot(disk_B, hit_Ng)); - /* multiple importance sample between 3 axes, power heuristic - * found to be slightly better than balance heuristic */ - float mis_weight = power_heuristic_3(pdf_N, pdf_T, pdf_B); + /* Multiple importance sample between 3 axes, power heuristic + * found to be slightly better than balance heuristic. pdf_N + * in the MIS weight and denominator cancelled out. */ + float w = pdf_N / (sqr(pdf_N) + sqr(pdf_T) + sqr(pdf_B)); + if(ss_isect->num_hits > BSSRDF_MAX_HITS) { + w *= ss_isect->num_hits/(float)BSSRDF_MAX_HITS; + } - /* real distance to sampled point */ + /* Real distance to sampled point. */ float r = len(hit_P - sd->P); - /* evaluate */ - float w = mis_weight / pdf_N; - if(ss_isect->num_hits > BSSRDF_MAX_HITS) - w *= ss_isect->num_hits/(float)BSSRDF_MAX_HITS; + /* Evaluate profiles. */ float3 eval = subsurface_scatter_eval(sd, sc, disk_r, r, all) * w; ss_isect->weight[hit] = eval; } +#ifdef __SPLIT_KERNEL__ + ss_isect->ray = *ray; +#endif + return num_eval_hits; } ccl_device_noinline void subsurface_scatter_multi_setup( KernelGlobals *kg, - SubsurfaceIntersection* ss_isect, + LocalIntersection* ss_isect, int hit, ShaderData *sd, - PathState *state, - int state_flag, - ShaderClosure *sc, - bool all) + ccl_addr_space PathState *state, + const ShaderClosure *sc) { +#ifdef __SPLIT_KERNEL__ + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; +#else + Ray *ray = &ss_isect->ray; +#endif + + /* Workaround for AMD GPU OpenCL compiler. Most probably cache bypass issue. */ +#if defined(__SPLIT_KERNEL__) && defined(__KERNEL_OPENCL_AMD__) && defined(__KERNEL_GPU__) + kernel_split_params.dummy_sd_flag = sd->flag; +#endif + /* Setup new shading point. */ - shader_setup_from_subsurface(kg, sd, &ss_isect->hits[hit], &ss_isect->ray); + shader_setup_from_subsurface(kg, sd, &ss_isect->hits[hit], ray); /* Optionally blur colors and bump mapping. */ float3 weight = ss_isect->weight[hit]; float3 N = sd->N; - subsurface_color_bump_blur(kg, sd, state, state_flag, &weight, &N); + subsurface_color_bump_blur(kg, sd, state, &weight, &N); /* Setup diffuse BSDF. */ - subsurface_scatter_setup_diffuse_bsdf(sd, weight, true, N); + subsurface_scatter_setup_diffuse_bsdf(kg, sd, sc, weight, N); } -/* subsurface scattering step, from a point on the surface to another nearby point on the same object */ -ccl_device void subsurface_scatter_step(KernelGlobals *kg, ShaderData *sd, PathState *state, - int state_flag, ShaderClosure *sc, uint *lcg_state, float disk_u, float disk_v, bool all) +/* Random walk subsurface scattering. + * + * "Practical and Controllable Subsurface Scattering for Production Path + * Tracing". Matt Jen-Yuan Chiang, Peter Kutz, Brent Burley. SIGGRAPH 2016. */ + +ccl_device void subsurface_random_walk_remap( + const float A, + const float d, + float *sigma_t, + float *sigma_s) { - float3 eval = make_float3(0.0f, 0.0f, 0.0f); + /* Compute attenuation and scattering coefficients from albedo. */ + const float a = 1.0f - expf(A * (-5.09406f + A * (2.61188f - A * 4.31805f))); + const float s = 1.9f - A + 3.5f * sqr(A - 0.8f); - /* pick random axis in local frame and point on disk */ - float3 disk_N, disk_T, disk_B; - float pick_pdf_N, pick_pdf_T, pick_pdf_B; + *sigma_t = 1.0f / fmaxf(d * s, 1e-16f); + *sigma_s = *sigma_t * a; +} - disk_N = sd->Ng; - make_orthonormals(disk_N, &disk_T, &disk_B); +ccl_device void subsurface_random_walk_coefficients( + const ShaderClosure *sc, + float3 *sigma_t, + float3 *sigma_s, + float3 *weight) +{ + const Bssrdf *bssrdf = (const Bssrdf*)sc; + const float3 A = bssrdf->albedo; + const float3 d = bssrdf->radius; + float sigma_t_x, sigma_t_y, sigma_t_z; + float sigma_s_x, sigma_s_y, sigma_s_z; - if(sd->randb_closure < 0.5f) { - pick_pdf_N = 0.5f; - pick_pdf_T = 0.25f; - pick_pdf_B = 0.25f; - } - else if(sd->randb_closure < 0.75f) { - float3 tmp = disk_N; - disk_N = disk_T; - disk_T = tmp; - pick_pdf_N = 0.25f; - pick_pdf_T = 0.5f; - pick_pdf_B = 0.25f; - } - else { - float3 tmp = disk_N; - disk_N = disk_B; - disk_B = tmp; - pick_pdf_N = 0.25f; - pick_pdf_T = 0.25f; - pick_pdf_B = 0.5f; + subsurface_random_walk_remap(A.x, d.x, &sigma_t_x, &sigma_s_x); + subsurface_random_walk_remap(A.y, d.y, &sigma_t_y, &sigma_s_y); + subsurface_random_walk_remap(A.z, d.z, &sigma_t_z, &sigma_s_z); + + *sigma_t = make_float3(sigma_t_x, sigma_t_y, sigma_t_z); + *sigma_s = make_float3(sigma_s_x, sigma_s_y, sigma_s_z); + + /* Closure mixing and Fresnel weights separate from albedo. */ + *weight = safe_divide_color(bssrdf->weight, A); +} + +ccl_device_noinline bool subsurface_random_walk( + KernelGlobals *kg, + LocalIntersection *ss_isect, + ShaderData *sd, + ccl_addr_space PathState *state, + const ShaderClosure *sc, + const float bssrdf_u, + const float bssrdf_v) +{ + /* Sample diffuse surface scatter into the object. */ + float3 D; + float pdf; + sample_cos_hemisphere(-sd->N, bssrdf_u, bssrdf_v, &D, &pdf); + if(dot(-sd->Ng, D) <= 0.0f) { + return 0; } - /* sample point on disk */ - float phi = M_2PI_F * disk_u; - float disk_r = disk_v; - float disk_height; + /* Convert subsurface to volume coefficients. */ + float3 sigma_t, sigma_s; + float3 throughput = make_float3(1.0f, 1.0f, 1.0f); + subsurface_random_walk_coefficients(sc, &sigma_t, &sigma_s, &throughput); + + /* Setup ray. */ +#ifdef __SPLIT_KERNEL__ + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; +#else + Ray *ray = &ss_isect->ray; +#endif + ray->P = ray_offset(sd->P, -sd->Ng); + ray->D = D; + ray->t = FLT_MAX; + ray->time = sd->time; - bssrdf_sample(sc, disk_r, &disk_r, &disk_height); + /* Modify state for RNGs, decorrelated from other paths. */ + uint prev_rng_offset = state->rng_offset; + uint prev_rng_hash = state->rng_hash; + state->rng_hash = cmj_hash(state->rng_hash + state->rng_offset, 0xdeadbeef); - float3 disk_P = (disk_r*cosf(phi)) * disk_T + (disk_r*sinf(phi)) * disk_B; + /* Random walk until we hit the surface again. */ + bool hit = false; - /* create ray */ - Ray ray; - ray.P = sd->P + disk_N*disk_height + disk_P; - ray.D = -disk_N; - ray.t = 2.0f*disk_height; - ray.dP = sd->dP; - ray.dD = differential3_zero(); - ray.time = sd->time; - - /* intersect with the same object. if multiple intersections are - * found it will randomly pick one of them */ - SubsurfaceIntersection ss_isect; - scene_intersect_subsurface(kg, &ray, &ss_isect, sd->object, lcg_state, 1); - - /* evaluate bssrdf */ - if(ss_isect.num_hits > 0) { - float3 origP = sd->P; - - /* setup new shading point */ - shader_setup_from_subsurface(kg, sd, &ss_isect.hits[0], &ray); - - /* probability densities for local frame axes */ - float pdf_N = pick_pdf_N * fabsf(dot(disk_N, sd->Ng)); - float pdf_T = pick_pdf_T * fabsf(dot(disk_T, sd->Ng)); - float pdf_B = pick_pdf_B * fabsf(dot(disk_B, sd->Ng)); - - /* multiple importance sample between 3 axes, power heuristic - * found to be slightly better than balance heuristic */ - float mis_weight = power_heuristic_3(pdf_N, pdf_T, pdf_B); - - /* real distance to sampled point */ - float r = len(sd->P - origP); - - /* evaluate */ - float w = (mis_weight * ss_isect.num_hits) / pdf_N; - eval = subsurface_scatter_eval(sd, sc, disk_r, r, all) * w; + for(int bounce = 0; bounce < BSSRDF_MAX_BOUNCES; bounce++) { + /* Advance random number offset. */ + state->rng_offset += PRNG_BOUNCE_NUM; + + if(bounce > 0) { + /* Sample scattering direction. */ + const float anisotropy = 0.0f; + float scatter_u, scatter_v; + path_state_rng_2D(kg, state, PRNG_BSDF_U, &scatter_u, &scatter_v); + ray->D = henyey_greenstrein_sample(ray->D, anisotropy, scatter_u, scatter_v, NULL); + } + + /* Sample color channel, use MIS with balance heuristic. */ + float rphase = path_state_rng_1D(kg, state, PRNG_PHASE_CHANNEL); + float3 albedo = safe_divide_color(sigma_s, sigma_t); + float3 channel_pdf; + int channel = kernel_volume_sample_channel(albedo, throughput, rphase, &channel_pdf); + + /* Distance sampling. */ + float rdist = path_state_rng_1D(kg, state, PRNG_SCATTER_DISTANCE); + float sample_sigma_t = kernel_volume_channel_get(sigma_t, channel); + float t = -logf(1.0f - rdist)/sample_sigma_t; + + ray->t = t; + scene_intersect_local(kg, *ray, ss_isect, sd->object, NULL, 1); + hit = (ss_isect->num_hits > 0); + + if(hit) { + /* Compute world space distance to surface hit. */ + float3 D = ray->D; + object_inverse_dir_transform(kg, sd, &D); + D = normalize(D) * ss_isect->hits[0].t; + object_dir_transform(kg, sd, &D); + t = len(D); + } + + /* Advance to new scatter location. */ + ray->P += t * ray->D; + + /* Update throughput. */ + float3 transmittance = volume_color_transmittance(sigma_t, t); + float pdf = dot(channel_pdf, (hit)? transmittance: sigma_t * transmittance); + throughput *= ((hit)? transmittance: sigma_s * transmittance) / pdf; + + if(hit) { + /* If we hit the surface, we are done. */ + break; + } + + /* Russian roulette. */ + float terminate = path_state_rng_1D(kg, state, PRNG_TERMINATE); + float probability = min(max3(fabs(throughput)), 1.0f); + if(terminate >= probability) { + break; + } + throughput /= probability; } - /* optionally blur colors and bump mapping */ - float3 N = sd->N; - subsurface_color_bump_blur(kg, sd, state, state_flag, &eval, &N); + kernel_assert(isfinite_safe(throughput.x) && + isfinite_safe(throughput.y) && + isfinite_safe(throughput.z)); - /* setup diffuse bsdf */ - subsurface_scatter_setup_diffuse_bsdf(sd, eval, (ss_isect.num_hits > 0), N); + state->rng_offset = prev_rng_offset; + state->rng_hash = prev_rng_hash; + + /* Return number of hits in ss_isect. */ + if(!hit) { + return 0; + } + + /* TODO: gain back performance lost from merging with disk BSSRDF. We + * only need to return on hit so this indirect ray push/pop overhead + * is not actually needed, but it does keep the code simpler. */ + ss_isect->weight[0] = throughput; +#ifdef __SPLIT_KERNEL__ + ss_isect->ray = *ray; +#endif + + return 1; +} + +ccl_device_inline int subsurface_scatter_multi_intersect( + KernelGlobals *kg, + LocalIntersection *ss_isect, + ShaderData *sd, + ccl_addr_space PathState *state, + const ShaderClosure *sc, + uint *lcg_state, + float bssrdf_u, + float bssrdf_v, + bool all) +{ + if(CLOSURE_IS_DISK_BSSRDF(sc->type)) { + return subsurface_scatter_disk(kg, + ss_isect, + sd, + sc, + lcg_state, + bssrdf_u, + bssrdf_v, + all); + } + else { + return subsurface_random_walk(kg, + ss_isect, + sd, + state, + sc, + bssrdf_u, + bssrdf_v); + } } CCL_NAMESPACE_END |