Cycles: merge of cycles-x branch, a major update to the renderer

This includes much improved GPU rendering performance, viewport interactivity,
new shadow catcher, revamped sampling settings, subsurface scattering anisotropy,
new GPU volume sampling, improved PMJ sampling pattern, and more.

Some features have also been removed or changed, breaking backwards compatibility.
Including the removal of the OpenCL backend, for which alternatives are under
development.

Release notes and code docs:
https://wiki.blender.org/wiki/Reference/Release_Notes/3.0/Cycles
https://wiki.blender.org/wiki/Source/Render/Cycles

Credits:
* Sergey Sharybin
* Brecht Van Lommel
* Patrick Mours (OptiX backend)
* Christophe Hery (subsurface scattering anisotropy)
* William Leeson (PMJ sampling pattern)
* Alaska (various fixes and tweaks)
* Thomas Dinges (various fixes)

For the full commit history, see the cycles-x branch. This squashes together
all the changes since intermediate changes would often fail building or tests.

Ref T87839, T87837, T87836
Fixes T90734, T89353, T80267, T80267, T77185, T69800

1 files changed, 0 insertions, 556 deletions

diff --git a/intern/cycles/kernel/kernel_path_branched.h b/intern/cycles/kernel/kernel_path_branched.h
deleted file mode 100644
index a1ee1bc107e..00000000000
--- a/intern/cycles/kernel/kernel_path_branched.h
+++ /dev/null
@@ -1,556 +0,0 @@
-/*
- * Copyright 2011-2013 Blender Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-CCL_NAMESPACE_BEGIN
-
-#ifdef __BRANCHED_PATH__
-
-ccl_device_inline void kernel_branched_path_ao(KernelGlobals *kg,
-                                               ShaderData *sd,
-                                               ShaderData *emission_sd,
-                                               PathRadiance *L,
-                                               ccl_addr_space PathState *state,
-                                               float3 throughput)
-{
-  int num_samples = kernel_data.integrator.ao_samples;
-  float num_samples_inv = 1.0f / num_samples;
-  float ao_factor = kernel_data.background.ao_factor;
-  float3 ao_N;
-  float3 ao_bsdf = shader_bsdf_ao(kg, sd, ao_factor, &ao_N);
-  float3 ao_alpha = shader_bsdf_alpha(kg, sd);
-
-  for (int j = 0; j < num_samples; j++) {
-    float bsdf_u, bsdf_v;
-    path_branched_rng_2D(
-        kg, state->rng_hash, state, j, num_samples, PRNG_BSDF_U, &bsdf_u, &bsdf_v);
-
-    float3 ao_D;
-    float ao_pdf;
-
-    sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
-
-    if (dot(sd->Ng, ao_D) > 0.0f && ao_pdf != 0.0f) {
-      Ray light_ray;
-      float3 ao_shadow;
-
-      light_ray.P = ray_offset(sd->P, sd->Ng);
-      light_ray.D = ao_D;
-      light_ray.t = kernel_data.background.ao_distance;
-      light_ray.time = sd->time;
-      light_ray.dP = sd->dP;
-      light_ray.dD = differential3_zero();
-
-      if (!shadow_blocked(kg, sd, emission_sd, state, &light_ray, &ao_shadow)) {
-        path_radiance_accum_ao(
-            kg, L, state, throughput * num_samples_inv, ao_alpha, ao_bsdf, ao_shadow);
-      }
-      else {
-        path_radiance_accum_total_ao(L, state, throughput * num_samples_inv, ao_bsdf);
-      }
-    }
-  }
-}
-
-#  ifndef __SPLIT_KERNEL__
-
-#    ifdef __VOLUME__
-ccl_device_forceinline void kernel_branched_path_volume(KernelGlobals *kg,
-                                                        ShaderData *sd,
-                                                        PathState *state,
-                                                        Ray *ray,
-                                                        float3 *throughput,
-                                                        ccl_addr_space Intersection *isect,
-                                                        bool hit,
-                                                        ShaderData *indirect_sd,
-                                                        ShaderData *emission_sd,
-                                                        PathRadiance *L)
-{
-  /* Sanitize volume stack. */
-  if (!hit) {
-    kernel_volume_clean_stack(kg, state->volume_stack);
-  }
-
-  if (state->volume_stack[0].shader == SHADER_NONE) {
-    return;
-  }
-
-  /* volume attenuation, emission, scatter */
-  Ray volume_ray = *ray;
-  volume_ray.t = (hit) ? isect->t : FLT_MAX;
-
-  float step_size = volume_stack_step_size(kg, state->volume_stack);
-  const int object = sd->object;
-
-#      ifdef __VOLUME_DECOUPLED__
-  /* decoupled ray marching only supported on CPU */
-  if (kernel_data.integrator.volume_decoupled) {
-    /* cache steps along volume for repeated sampling */
-    VolumeSegment volume_segment;
-
-    shader_setup_from_volume(kg, sd, &volume_ray);
-    kernel_volume_decoupled_record(kg, state, &volume_ray, sd, &volume_segment, step_size);
-
-    /* direct light sampling */
-    if (volume_segment.closure_flag & SD_SCATTER) {
-      volume_segment.sampling_method = volume_stack_sampling_method(kg, state->volume_stack);
-
-      int all = kernel_data.integrator.sample_all_lights_direct;
-
-      kernel_branched_path_volume_connect_light(
-          kg, sd, emission_sd, *throughput, state, L, all, &volume_ray, &volume_segment);
-
-      /* indirect light sampling */
-      int num_samples = kernel_data.integrator.volume_samples;
-      float num_samples_inv = 1.0f / num_samples;
-
-      for (int j = 0; j < num_samples; j++) {
-        PathState ps = *state;
-        Ray pray = *ray;
-        float3 tp = *throughput;
-
-        /* branch RNG state */
-        path_state_branch(&ps, j, num_samples);
-
-        /* scatter sample. if we use distance sampling and take just one
-         * sample for direct and indirect light, we could share this
-         * computation, but makes code a bit complex */
-        float rphase = path_state_rng_1D(kg, &ps, PRNG_PHASE_CHANNEL);
-        float rscatter = path_state_rng_1D(kg, &ps, PRNG_SCATTER_DISTANCE);
-
-        VolumeIntegrateResult result = kernel_volume_decoupled_scatter(
-            kg, &ps, &pray, sd, &tp, rphase, rscatter, &volume_segment, NULL, false);
-
-        if (result == VOLUME_PATH_SCATTERED &&
-            kernel_path_volume_bounce(kg, sd, &tp, &ps, &L->state, &pray)) {
-          kernel_path_indirect(
-              kg, indirect_sd, emission_sd, &pray, tp * num_samples_inv, &ps, L, object);
-
-          /* for render passes, sum and reset indirect light pass variables
-           * for the next samples */
-          path_radiance_sum_indirect(L);
-          path_radiance_reset_indirect(L);
-        }
-      }
-    }
-
-    /* emission and transmittance */
-    if (volume_segment.closure_flag & SD_EMISSION)
-      path_radiance_accum_emission(kg, L, state, *throughput, volume_segment.accum_emission);
-    *throughput *= volume_segment.accum_transmittance;
-
-    /* free cached steps */
-    kernel_volume_decoupled_free(kg, &volume_segment);
-  }
-  else
-#      endif /* __VOLUME_DECOUPLED__ */
-  {
-    /* GPU: no decoupled ray marching, scatter probabilistically. */
-    int num_samples = kernel_data.integrator.volume_samples;
-    float num_samples_inv = 1.0f / num_samples;
-
-    /* todo: we should cache the shader evaluations from stepping
-     * through the volume, for now we redo them multiple times */
-
-    for (int j = 0; j < num_samples; j++) {
-      PathState ps = *state;
-      Ray pray = *ray;
-      float3 tp = (*throughput) * num_samples_inv;
-
-      /* branch RNG state */
-      path_state_branch(&ps, j, num_samples);
-
-      VolumeIntegrateResult result = kernel_volume_integrate(
-          kg, &ps, sd, &volume_ray, L, &tp, step_size);
-
-#      ifdef __VOLUME_SCATTER__
-      if (result == VOLUME_PATH_SCATTERED) {
-        /* todo: support equiangular, MIS and all light sampling.
-         * alternatively get decoupled ray marching working on the GPU */
-        kernel_path_volume_connect_light(kg, sd, emission_sd, tp, state, L);
-
-        if (kernel_path_volume_bounce(kg, sd, &tp, &ps, &L->state, &pray)) {
-          kernel_path_indirect(kg, indirect_sd, emission_sd, &pray, tp, &ps, L, object);
-
-          /* for render passes, sum and reset indirect light pass variables
-           * for the next samples */
-          path_radiance_sum_indirect(L);
-          path_radiance_reset_indirect(L);
-        }
-      }
-#      endif /* __VOLUME_SCATTER__ */
-    }
-
-    /* todo: avoid this calculation using decoupled ray marching */
-    kernel_volume_shadow(kg, emission_sd, state, &volume_ray, throughput);
-  }
-}
-#    endif /* __VOLUME__ */
-
-/* bounce off surface and integrate indirect light */
-ccl_device_noinline_cpu void kernel_branched_path_surface_indirect_light(KernelGlobals *kg,
-                                                                         ShaderData *sd,
-                                                                         ShaderData *indirect_sd,
-                                                                         ShaderData *emission_sd,
-                                                                         float3 throughput,
-                                                                         float num_samples_adjust,
-                                                                         PathState *state,
-                                                                         PathRadiance *L)
-{
-  float sum_sample_weight = 0.0f;
-#    ifdef __DENOISING_FEATURES__
-  if (state->denoising_feature_weight > 0.0f) {
-    for (int i = 0; i < sd->num_closure; i++) {
-      const ShaderClosure *sc = &sd->closure[i];
-
-      /* transparency is not handled here, but in outer loop */
-      if (!CLOSURE_IS_BSDF(sc->type) || CLOSURE_IS_BSDF_TRANSPARENT(sc->type)) {
-        continue;
-      }
-
-      sum_sample_weight += sc->sample_weight;
-    }
-  }
-  else {
-    sum_sample_weight = 1.0f;
-  }
-#    endif /* __DENOISING_FEATURES__ */
-
-  for (int i = 0; i < sd->num_closure; i++) {
-    const ShaderClosure *sc = &sd->closure[i];
-
-    /* transparency is not handled here, but in outer loop */
-    if (!CLOSURE_IS_BSDF(sc->type) || CLOSURE_IS_BSDF_TRANSPARENT(sc->type)) {
-      continue;
-    }
-
-    int num_samples;
-
-    if (CLOSURE_IS_BSDF_DIFFUSE(sc->type))
-      num_samples = kernel_data.integrator.diffuse_samples;
-    else if (CLOSURE_IS_BSDF_BSSRDF(sc->type))
-      num_samples = 1;
-    else if (CLOSURE_IS_BSDF_GLOSSY(sc->type))
-      num_samples = kernel_data.integrator.glossy_samples;
-    else
-      num_samples = kernel_data.integrator.transmission_samples;
-
-    num_samples = ceil_to_int(num_samples_adjust * num_samples);
-
-    float num_samples_inv = num_samples_adjust / num_samples;
-
-    for (int j = 0; j < num_samples; j++) {
-      PathState ps = *state;
-      float3 tp = throughput;
-      Ray bsdf_ray;
-#    ifdef __SHADOW_TRICKS__
-      float shadow_transparency = L->shadow_transparency;
-#    endif
-
-      ps.rng_hash = cmj_hash(state->rng_hash, i);
-
-      if (!kernel_branched_path_surface_bounce(
-              kg, sd, sc, j, num_samples, &tp, &ps, &L->state, &bsdf_ray, sum_sample_weight)) {
-        continue;
-      }
-
-      ps.rng_hash = state->rng_hash;
-
-      kernel_path_indirect(
-          kg, indirect_sd, emission_sd, &bsdf_ray, tp * num_samples_inv, &ps, L, sd->object);
-
-      /* for render passes, sum and reset indirect light pass variables
-       * for the next samples */
-      path_radiance_sum_indirect(L);
-      path_radiance_reset_indirect(L);
-
-#    ifdef __SHADOW_TRICKS__
-      L->shadow_transparency = shadow_transparency;
-#    endif
-    }
-  }
-}
-
-#    ifdef __SUBSURFACE__
-ccl_device void kernel_branched_path_subsurface_scatter(KernelGlobals *kg,
-                                                        ShaderData *sd,
-                                                        ShaderData *indirect_sd,
-                                                        ShaderData *emission_sd,
-                                                        PathRadiance *L,
-                                                        PathState *state,
-                                                        Ray *ray,
-                                                        float3 throughput)
-{
-  for (int i = 0; i < sd->num_closure; i++) {
-    ShaderClosure *sc = &sd->closure[i];
-
-    if (!CLOSURE_IS_BSSRDF(sc->type))
-      continue;
-
-    /* set up random number generator */
-    uint lcg_state = lcg_state_init(state, 0x68bc21eb);
-    int num_samples = kernel_data.integrator.subsurface_samples * 3;
-    float num_samples_inv = 1.0f / num_samples;
-    uint bssrdf_rng_hash = cmj_hash(state->rng_hash, i);
-
-    /* do subsurface scatter step with copy of shader data, this will
-     * replace the BSSRDF with a diffuse BSDF closure */
-    for (int j = 0; j < num_samples; j++) {
-      PathState hit_state = *state;
-      path_state_branch(&hit_state, j, num_samples);
-      hit_state.rng_hash = bssrdf_rng_hash;
-
-      LocalIntersection ss_isect;
-      float bssrdf_u, bssrdf_v;
-      path_state_rng_2D(kg, &hit_state, PRNG_BSDF_U, &bssrdf_u, &bssrdf_v);
-      int num_hits = subsurface_scatter_multi_intersect(
-          kg, &ss_isect, sd, &hit_state, sc, &lcg_state, bssrdf_u, bssrdf_v, true);
-
-      hit_state.rng_offset += PRNG_BOUNCE_NUM;
-
-#      ifdef __VOLUME__
-      Ray volume_ray = *ray;
-      bool need_update_volume_stack = kernel_data.integrator.use_volumes &&
-                                      sd->object_flag & SD_OBJECT_INTERSECTS_VOLUME;
-#      endif /* __VOLUME__ */
-
-      /* compute lighting with the BSDF closure */
-      for (int hit = 0; hit < num_hits; hit++) {
-        ShaderData bssrdf_sd = *sd;
-        Bssrdf *bssrdf = (Bssrdf *)sc;
-        ClosureType bssrdf_type = sc->type;
-        float bssrdf_roughness = bssrdf->roughness;
-        subsurface_scatter_multi_setup(
-            kg, &ss_isect, hit, &bssrdf_sd, &hit_state, bssrdf_type, bssrdf_roughness);
-
-#      ifdef __VOLUME__
-        if (need_update_volume_stack) {
-          /* Setup ray from previous surface point to the new one. */
-          float3 P = ray_offset(bssrdf_sd.P, -bssrdf_sd.Ng);
-          volume_ray.D = normalize_len(P - volume_ray.P, &volume_ray.t);
-
-          for (int k = 0; k < VOLUME_STACK_SIZE; k++) {
-            hit_state.volume_stack[k] = state->volume_stack[k];
-          }
-
-          kernel_volume_stack_update_for_subsurface(
-              kg, emission_sd, &volume_ray, hit_state.volume_stack);
-        }
-#      endif /* __VOLUME__ */
-
-#      ifdef __EMISSION__
-        /* direct light */
-        if (kernel_data.integrator.use_direct_light) {
-          int all = (kernel_data.integrator.sample_all_lights_direct) ||
-                    (hit_state.flag & PATH_RAY_SHADOW_CATCHER);
-          kernel_branched_path_surface_connect_light(
-              kg, &bssrdf_sd, emission_sd, &hit_state, throughput, num_samples_inv, L, all);
-        }
-#      endif /* __EMISSION__ */
-
-        /* indirect light */
-        kernel_branched_path_surface_indirect_light(
-            kg, &bssrdf_sd, indirect_sd, emission_sd, throughput, num_samples_inv, &hit_state, L);
-      }
-    }
-  }
-}
-#    endif /* __SUBSURFACE__ */
-
-ccl_device void kernel_branched_path_integrate(KernelGlobals *kg,
-                                               uint rng_hash,
-                                               int sample,
-                                               Ray ray,
-                                               ccl_global float *buffer,
-                                               PathRadiance *L)
-{
-  /* initialize */
-  float3 throughput = one_float3();
-
-  path_radiance_init(kg, L);
-
-  /* shader data memory used for both volumes and surfaces, saves stack space */
-  ShaderData sd;
-  /* shader data used by emission, shadows, volume stacks, indirect path */
-  ShaderDataTinyStorage emission_sd_storage;
-  ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
-  ShaderData indirect_sd;
-
-  PathState state;
-  path_state_init(kg, emission_sd, &state, rng_hash, sample, &ray);
-
-  /* Main Loop
-   * Here we only handle transparency intersections from the camera ray.
-   * Indirect bounces are handled in kernel_branched_path_surface_indirect_light().
-   */
-  for (;;) {
-    /* Find intersection with objects in scene. */
-    Intersection isect;
-    bool hit = kernel_path_scene_intersect(kg, &state, &ray, &isect, L, sd.object);
-
-#    ifdef __VOLUME__
-    /* Volume integration. */
-    kernel_branched_path_volume(
-        kg, &sd, &state, &ray, &throughput, &isect, hit, &indirect_sd, emission_sd, L);
-#    endif /* __VOLUME__ */
-
-    /* Shade background. */
-    if (!hit) {
-      kernel_path_background(kg, &state, &ray, throughput, &sd, buffer, L);
-      break;
-    }
-
-    /* Setup and evaluate shader. */
-    shader_setup_from_ray(kg, &sd, &isect, &ray);
-
-    /* Skip most work for volume bounding surface. */
-#    ifdef __VOLUME__
-    if (!(sd.flag & SD_HAS_ONLY_VOLUME)) {
-#    endif
-
-      shader_eval_surface(kg, &sd, &state, buffer, state.flag);
-      shader_merge_closures(&sd);
-
-      /* Apply shadow catcher, holdout, emission. */
-      if (!kernel_path_shader_apply(kg, &sd, &state, &ray, throughput, emission_sd, L, buffer)) {
-        break;
-      }
-
-      /* transparency termination */
-      if (state.flag & PATH_RAY_TRANSPARENT) {
-        /* path termination. this is a strange place to put the termination, it's
-         * mainly due to the mixed in MIS that we use. gives too many unneeded
-         * shader evaluations, only need emission if we are going to terminate */
-        float probability = path_state_continuation_probability(kg, &state, throughput);
-
-        if (probability == 0.0f) {
-          break;
-        }
-        else if (probability != 1.0f) {
-          float terminate = path_state_rng_1D(kg, &state, PRNG_TERMINATE);
-
-          if (terminate >= probability)
-            break;
-
-          throughput /= probability;
-        }
-      }
-
-#    ifdef __DENOISING_FEATURES__
-      kernel_update_denoising_features(kg, &sd, &state, L);
-#    endif
-
-#    ifdef __AO__
-      /* ambient occlusion */
-      if (kernel_data.integrator.use_ambient_occlusion) {
-        kernel_branched_path_ao(kg, &sd, emission_sd, L, &state, throughput);
-      }
-#    endif /* __AO__ */
-
-#    ifdef __SUBSURFACE__
-      /* bssrdf scatter to a different location on the same object */
-      if (sd.flag & SD_BSSRDF) {
-        kernel_branched_path_subsurface_scatter(
-            kg, &sd, &indirect_sd, emission_sd, L, &state, &ray, throughput);
-      }
-#    endif /* __SUBSURFACE__ */
-
-      PathState hit_state = state;
-
-#    ifdef __EMISSION__
-      /* direct light */
-      if (kernel_data.integrator.use_direct_light) {
-        int all = (kernel_data.integrator.sample_all_lights_direct) ||
-                  (state.flag & PATH_RAY_SHADOW_CATCHER);
-        kernel_branched_path_surface_connect_light(
-            kg, &sd, emission_sd, &hit_state, throughput, 1.0f, L, all);
-      }
-#    endif /* __EMISSION__ */
-
-      /* indirect light */
-      kernel_branched_path_surface_indirect_light(
-          kg, &sd, &indirect_sd, emission_sd, throughput, 1.0f, &hit_state, L);
-
-      /* continue in case of transparency */
-      throughput *= shader_bsdf_transparency(kg, &sd);
-
-      if (is_zero(throughput))
-        break;
-
-      /* Update Path State */
-      path_state_next(kg, &state, LABEL_TRANSPARENT);
-
-#    ifdef __VOLUME__
-    }
-    else {
-      if (!path_state_volume_next(kg, &state)) {
-        break;
-      }
-    }
-#    endif
-
-    ray.P = ray_offset(sd.P, -sd.Ng);
-    ray.t -= sd.ray_length; /* clipping works through transparent */
-
-#    ifdef __RAY_DIFFERENTIALS__
-    ray.dP = sd.dP;
-    ray.dD.dx = -sd.dI.dx;
-    ray.dD.dy = -sd.dI.dy;
-#    endif /* __RAY_DIFFERENTIALS__ */
-
-#    ifdef __VOLUME__
-    /* enter/exit volume */
-    kernel_volume_stack_enter_exit(kg, &sd, state.volume_stack);
-#    endif /* __VOLUME__ */
-  }
-}
-
-ccl_device void kernel_branched_path_trace(
-    KernelGlobals *kg, ccl_global float *buffer, int sample, int x, int y, int offset, int stride)
-{
-  /* buffer offset */
-  int index = offset + x + y * stride;
-  int pass_stride = kernel_data.film.pass_stride;
-
-  buffer += index * pass_stride;
-
-  if (kernel_data.film.pass_adaptive_aux_buffer) {
-    ccl_global float4 *aux = (ccl_global float4 *)(buffer +
-                                                   kernel_data.film.pass_adaptive_aux_buffer);
-    if ((*aux).w > 0.0f) {
-      return;
-    }
-  }
-
-  /* initialize random numbers and ray */
-  uint rng_hash;
-  Ray ray;
-
-  kernel_path_trace_setup(kg, sample, x, y, &rng_hash, &ray);
-
-  /* integrate */
-  PathRadiance L;
-
-  if (ray.t != 0.0f) {
-    kernel_branched_path_integrate(kg, rng_hash, sample, ray, buffer, &L);
-    kernel_write_result(kg, buffer, sample, &L);
-  }
-}
-
-#  endif /* __SPLIT_KERNEL__ */
-
-#endif /* __BRANCHED_PATH__ */
-
-CCL_NAMESPACE_END