diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_subsurface.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_subsurface.h | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/intern/cycles/kernel/kernel_subsurface.h b/intern/cycles/kernel/kernel_subsurface.h index 616ad71af3c..c79992ee99b 100644 --- a/intern/cycles/kernel/kernel_subsurface.h +++ b/intern/cycles/kernel/kernel_subsurface.h @@ -283,22 +283,23 @@ 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; @@ -417,20 +418,21 @@ ccl_device void subsurface_scatter_step(KernelGlobals *kg, ShaderData *sd, ccl_a /* setup new shading point */ shader_setup_from_subsurface(kg, sd, &ss_isect.hits[0], &ray); - /* probability densities for local frame axes */ + /* 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); + /* 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)); + w *= ss_isect.num_hits; - /* real distance to sampled point */ + /* Real distance to sampled point. */ float r = len(sd->P - origP); - /* evaluate */ - float w = (mis_weight * ss_isect.num_hits) / pdf_N; + /* Evaluate profiles. */ eval = subsurface_scatter_eval(sd, sc, disk_r, r, all) * w; } |