diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_subsurface.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_subsurface.h | 822 |
1 files changed, 391 insertions, 431 deletions
diff --git a/intern/cycles/kernel/kernel_subsurface.h b/intern/cycles/kernel/kernel_subsurface.h index 96b717530ce..7510e50a962 100644 --- a/intern/cycles/kernel/kernel_subsurface.h +++ b/intern/cycles/kernel/kernel_subsurface.h @@ -22,317 +22,295 @@ CCL_NAMESPACE_BEGIN * http://library.imageworks.com/pdfs/imageworks-library-BSSRDF-sampling.pdf */ -ccl_device_inline float3 subsurface_scatter_eval(ShaderData *sd, - const ShaderClosure *sc, - float disk_r, - float r, - bool all) +ccl_device_inline float3 +subsurface_scatter_eval(ShaderData *sd, const ShaderClosure *sc, float disk_r, float r, bool all) { - /* 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_inv = 0.0f; + /* 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_inv = 0.0f; - if(!all) { - float sample_weight_sum = 0.0f; + if (!all) { + float sample_weight_sum = 0.0f; - for(int i = 0; i < sd->num_closure; i++) { - sc = &sd->closure[i]; + 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; - } - } + if (CLOSURE_IS_DISK_BSSRDF(sc->type)) { + sample_weight_sum += sc->sample_weight; + } + } - 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]; + for (int i = 0; i < sd->num_closure; i++) { + sc = &sd->closure[i]; - 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; + 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 */ - float3 eval = bssrdf_eval(sc, r); - float pdf = bssrdf_pdf(sc, disk_r); + /* compute pdf */ + float3 eval = bssrdf_eval(sc, r); + float pdf = bssrdf_pdf(sc, disk_r); - eval_sum += sc->weight * eval; - pdf_sum += sample_weight * pdf; - } - } + 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); + return (pdf_sum > 0.0f) ? eval_sum / pdf_sum : make_float3(0.0f, 0.0f, 0.0f); } /* replace closures with a single diffuse bsdf closure after scatter step */ -ccl_device void subsurface_scatter_setup_diffuse_bsdf(KernelGlobals *kg, ShaderData *sd, ClosureType type, float roughness, float3 weight, float3 N) +ccl_device void subsurface_scatter_setup_diffuse_bsdf( + KernelGlobals *kg, ShaderData *sd, ClosureType type, float roughness, float3 weight, float3 N) { - sd->flag &= ~SD_CLOSURE_FLAGS; - sd->num_closure = 0; - sd->num_closure_left = kernel_data.integrator.max_closures; + sd->flag &= ~SD_CLOSURE_FLAGS; + sd->num_closure = 0; + sd->num_closure_left = kernel_data.integrator.max_closures; #ifdef __PRINCIPLED__ - if(type == CLOSURE_BSSRDF_PRINCIPLED_ID || - type == CLOSURE_BSSRDF_PRINCIPLED_RANDOM_WALK_ID) - { - PrincipledDiffuseBsdf *bsdf = (PrincipledDiffuseBsdf*)bsdf_alloc(sd, sizeof(PrincipledDiffuseBsdf), weight); - - if(bsdf) { - bsdf->N = N; - bsdf->roughness = roughness; - sd->flag |= bsdf_principled_diffuse_setup(bsdf); - - /* 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(type) || - CLOSURE_IS_BSSRDF(type)) -#endif /* __PRINCIPLED__ */ - { - DiffuseBsdf *bsdf = (DiffuseBsdf*)bsdf_alloc(sd, sizeof(DiffuseBsdf), weight); - - if(bsdf) { - bsdf->N = N; - sd->flag |= bsdf_diffuse_setup(bsdf); - - /* replace CLOSURE_BSDF_DIFFUSE_ID with this special ID so render passes - * can recognize it as not being a regular diffuse closure */ - bsdf->type = CLOSURE_BSDF_BSSRDF_ID; - } - } + if (type == CLOSURE_BSSRDF_PRINCIPLED_ID || type == CLOSURE_BSSRDF_PRINCIPLED_RANDOM_WALK_ID) { + PrincipledDiffuseBsdf *bsdf = (PrincipledDiffuseBsdf *)bsdf_alloc( + sd, sizeof(PrincipledDiffuseBsdf), weight); + + if (bsdf) { + bsdf->N = N; + bsdf->roughness = roughness; + sd->flag |= bsdf_principled_diffuse_setup(bsdf); + + /* 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(type) || CLOSURE_IS_BSSRDF(type)) +#endif /* __PRINCIPLED__ */ + { + DiffuseBsdf *bsdf = (DiffuseBsdf *)bsdf_alloc(sd, sizeof(DiffuseBsdf), weight); + + if (bsdf) { + bsdf->N = N; + sd->flag |= bsdf_diffuse_setup(bsdf); + + /* replace CLOSURE_BSDF_DIFFUSE_ID with this special ID so render passes + * can recognize it as not being a regular diffuse closure */ + bsdf->type = CLOSURE_BSDF_BSSRDF_ID; + } + } } /* optionally do blurring of color and/or bump mapping, at the cost of a shader evaluation */ ccl_device float3 subsurface_color_pow(float3 color, float exponent) { - color = max(color, make_float3(0.0f, 0.0f, 0.0f)); - - if(exponent == 1.0f) { - /* nothing to do */ - } - else if(exponent == 0.5f) { - color.x = sqrtf(color.x); - color.y = sqrtf(color.y); - color.z = sqrtf(color.z); - } - else { - color.x = powf(color.x, exponent); - color.y = powf(color.y, exponent); - color.z = powf(color.z, exponent); - } - - return color; + color = max(color, make_float3(0.0f, 0.0f, 0.0f)); + + if (exponent == 1.0f) { + /* nothing to do */ + } + else if (exponent == 0.5f) { + color.x = sqrtf(color.x); + color.y = sqrtf(color.y); + color.z = sqrtf(color.z); + } + else { + color.x = powf(color.x, exponent); + color.y = powf(color.y, exponent); + color.z = powf(color.z, exponent); + } + + return color; } -ccl_device void subsurface_color_bump_blur(KernelGlobals *kg, - ShaderData *sd, - ccl_addr_space PathState *state, - float3 *eval, - float3 *N) +ccl_device void subsurface_color_bump_blur( + KernelGlobals *kg, ShaderData *sd, ccl_addr_space PathState *state, float3 *eval, float3 *N) { - /* average color and texture blur at outgoing point */ - float texture_blur; - float3 out_color = shader_bssrdf_sum(sd, NULL, &texture_blur); - - /* do we have bump mapping? */ - bool bump = (sd->flag & SD_HAS_BSSRDF_BUMP) != 0; - - if(bump || texture_blur > 0.0f) { - /* average color and normal at incoming point */ - 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 - * of the other one. we could try to do this per closure but it's quite - * tricky to match closures between shader evaluations, their number and - * order may change, this is simpler */ - if(texture_blur > 0.0f) { - out_color = subsurface_color_pow(out_color, texture_blur); - in_color = subsurface_color_pow(in_color, texture_blur); - - *eval *= safe_divide_color(in_color, out_color); - } - } + /* average color and texture blur at outgoing point */ + float texture_blur; + float3 out_color = shader_bssrdf_sum(sd, NULL, &texture_blur); + + /* do we have bump mapping? */ + bool bump = (sd->flag & SD_HAS_BSSRDF_BUMP) != 0; + + if (bump || texture_blur > 0.0f) { + /* average color and normal at incoming point */ + 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 + * of the other one. we could try to do this per closure but it's quite + * tricky to match closures between shader evaluations, their number and + * order may change, this is simpler */ + if (texture_blur > 0.0f) { + out_color = subsurface_color_pow(out_color, texture_blur); + in_color = subsurface_color_pow(in_color, texture_blur); + + *eval *= safe_divide_color(in_color, out_color); + } + } } /* Subsurface scattering step, from a point on the surface to other * nearby points on the same object. */ -ccl_device_inline int subsurface_scatter_disk( - KernelGlobals *kg, - LocalIntersection *ss_isect, - ShaderData *sd, - const ShaderClosure *sc, - uint *lcg_state, - float disk_u, - float disk_v, - bool all) +ccl_device_inline int subsurface_scatter_disk(KernelGlobals *kg, + LocalIntersection *ss_isect, + ShaderData *sd, + const ShaderClosure *sc, + uint *lcg_state, + float disk_u, + float disk_v, + bool all) { - /* 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; - - disk_N = sd->Ng; - make_orthonormals(disk_N, &disk_T, &disk_B); - - if(disk_v < 0.5f) { - pick_pdf_N = 0.5f; - pick_pdf_T = 0.25f; - pick_pdf_B = 0.25f; - disk_v *= 2.0f; - } - 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; - disk_v = (disk_v - 0.5f)*4.0f; - } - 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; - disk_v = (disk_v - 0.75f)*4.0f; - } - - /* sample point on disk */ - float phi = M_2PI_F * disk_v; - float disk_height, disk_r; - - 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 */ + /* 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; + + disk_N = sd->Ng; + make_orthonormals(disk_N, &disk_T, &disk_B); + + if (disk_v < 0.5f) { + pick_pdf_N = 0.5f; + pick_pdf_T = 0.25f; + pick_pdf_B = 0.25f; + disk_v *= 2.0f; + } + 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; + disk_v = (disk_v - 0.5f) * 4.0f; + } + 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; + disk_v = (disk_v - 0.75f) * 4.0f; + } + + /* sample point on disk */ + float phi = M_2PI_F * disk_v; + float disk_height, disk_r; + + 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; + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; #else - Ray *ray = &ss_isect->ray; + 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; - ray->dP = sd->dP; - ray->dD = differential3_zero(); - ray->time = sd->time; - - /* 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_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(sd->type & PRIMITIVE_TRIANGLE) { - hit_P = triangle_refine_local(kg, - sd, - &ss_isect->hits[hit], - 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 use at most BSSRDF_MAX_HITS hits, a random subset of all 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 (sd->type & PRIMITIVE_TRIANGLE) { + hit_P = triangle_refine_local(kg, sd, &ss_isect->hits[hit], ray); + } #ifdef __OBJECT_MOTION__ - else if(sd->type & PRIMITIVE_MOTION_TRIANGLE) { - float3 verts[3]; - motion_triangle_vertices( - kg, - sd->object, - kernel_tex_fetch(__prim_index, ss_isect->hits[hit].prim), - sd->time, - verts); - hit_P = motion_triangle_refine_local(kg, - sd, - &ss_isect->hits[hit], - ray, - verts); - } -#endif /* __OBJECT_MOTION__ */ - else { - ss_isect->weight[hit] = make_float3(0.0f, 0.0f, 0.0f); - continue; - } - - float3 hit_Ng = ss_isect->Ng[hit]; - if(ss_isect->hits[hit].object != OBJECT_NONE) { - object_normal_transform(kg, sd, &hit_Ng); - } - - /* 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. 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. */ - float r = len(hit_P - sd->P); - - /* Evaluate profiles. */ - float3 eval = subsurface_scatter_eval(sd, sc, disk_r, r, all) * w; - - ss_isect->weight[hit] = eval; - } + else if (sd->type & PRIMITIVE_MOTION_TRIANGLE) { + float3 verts[3]; + motion_triangle_vertices(kg, + sd->object, + kernel_tex_fetch(__prim_index, ss_isect->hits[hit].prim), + sd->time, + verts); + hit_P = motion_triangle_refine_local(kg, sd, &ss_isect->hits[hit], ray, verts); + } +#endif /* __OBJECT_MOTION__ */ + else { + ss_isect->weight[hit] = make_float3(0.0f, 0.0f, 0.0f); + continue; + } + + float3 hit_Ng = ss_isect->Ng[hit]; + if (ss_isect->hits[hit].object != OBJECT_NONE) { + object_normal_transform(kg, sd, &hit_Ng); + } + + /* 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. 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. */ + float r = len(hit_P - sd->P); + + /* 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; + ss_isect->ray = *ray; #endif - return num_eval_hits; + return num_eval_hits; } -ccl_device_noinline void subsurface_scatter_multi_setup( - KernelGlobals *kg, - LocalIntersection* ss_isect, - int hit, - ShaderData *sd, - ccl_addr_space PathState *state, - ClosureType type, - float roughness) +ccl_device_noinline void subsurface_scatter_multi_setup(KernelGlobals *kg, + LocalIntersection *ss_isect, + int hit, + ShaderData *sd, + ccl_addr_space PathState *state, + ClosureType type, + float roughness) { #ifdef __SPLIT_KERNEL__ - Ray ray_object = ss_isect->ray; - Ray *ray = &ray_object; + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; #else - Ray *ray = &ss_isect->ray; + Ray *ray = &ss_isect->ray; #endif - /* Workaround for AMD GPU OpenCL compiler. Most probably cache bypass issue. */ + /* 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; + kernel_split_params.dummy_sd_flag = sd->flag; #endif - /* Setup new shading point. */ - shader_setup_from_subsurface(kg, sd, &ss_isect->hits[hit], ray); + /* Setup new shading point. */ + 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, &weight, &N); + /* Optionally blur colors and bump mapping. */ + float3 weight = ss_isect->weight[hit]; + float3 N = sd->N; + subsurface_color_bump_blur(kg, sd, state, &weight, &N); - /* Setup diffuse BSDF. */ - subsurface_scatter_setup_diffuse_bsdf(kg, sd, type, roughness, weight, N); + /* Setup diffuse BSDF. */ + subsurface_scatter_setup_diffuse_bsdf(kg, sd, type, roughness, weight, N); } /* Random walk subsurface scattering. @@ -340,196 +318,178 @@ ccl_device_noinline void subsurface_scatter_multi_setup( * "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) +ccl_device void subsurface_random_walk_remap(const float A, + const float d, + float *sigma_t, + float *sigma_s) { - /* 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); + /* 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); - *sigma_t = 1.0f / fmaxf(d * s, 1e-16f); - *sigma_s = *sigma_t * a; + *sigma_t = 1.0f / fmaxf(d * s, 1e-16f); + *sigma_s = *sigma_t * a; } -ccl_device void subsurface_random_walk_coefficients( - const ShaderClosure *sc, - float3 *sigma_t, - float3 *sigma_s, - float3 *weight) +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; + 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; - 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); + 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); + *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); + /* 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) +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; - } - - /* 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. */ + /* 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; + } + + /* 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; + Ray ray_object = ss_isect->ray; + Ray *ray = &ray_object; #else - Ray *ray = &ss_isect->ray; + 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; - - /* 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); - - /* Random walk until we hit the surface again. */ - bool hit = false; - - 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; - } - - kernel_assert(isfinite_safe(throughput.x) && - isfinite_safe(throughput.y) && - isfinite_safe(throughput.z)); - - 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; + ray->P = ray_offset(sd->P, -sd->Ng); + ray->D = D; + ray->t = FLT_MAX; + ray->time = sd->time; + + /* 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); + + /* Random walk until we hit the surface again. */ + bool hit = false; + + 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; + } + + kernel_assert(isfinite_safe(throughput.x) && isfinite_safe(throughput.y) && + isfinite_safe(throughput.z)); + + 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; + ss_isect->ray = *ray; #endif - return 1; + 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) +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); - } + 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 |