text: /*
   * Copyright 2011-2015 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
  
  /*This kernel takes care of setting up ray for the next iteration of
   * path-iteration and accumulating radiance corresponding to AO and
   * direct-lighting
   *
   * Ray state of rays that are terminated in this kernel are changed
   * to RAY_UPDATE_BUFFER.
   *
   * Note on queues:
   * This kernel fetches rays from the queue QUEUE_ACTIVE_AND_REGENERATED_RAYS
   * and processes only the rays of state RAY_ACTIVE.
   * There are different points in this kernel where a ray may terminate and
   * reach RAY_UPDATE_BUFF state. These rays are enqueued into
   * QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS queue. These rays will still be present
   * in QUEUE_ACTIVE_AND_REGENERATED_RAYS queue, but since their ray-state has
   * been changed to RAY_UPDATE_BUFF, there is no problem.
   *
   * State of queues when this kernel is called:
   * At entry,
   *   - QUEUE_ACTIVE_AND_REGENERATED_RAYS will be filled with RAY_ACTIVE,
   *     RAY_REGENERATED, RAY_UPDATE_BUFFER rays.
   *   - QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be filled with
   *     RAY_TO_REGENERATE and RAY_UPDATE_BUFFER rays.
   * At exit,
   *   - QUEUE_ACTIVE_AND_REGENERATED_RAYS will be filled with RAY_ACTIVE,
   *     RAY_REGENERATED and more RAY_UPDATE_BUFFER rays.
   *   - QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be filled with
   *     RAY_TO_REGENERATE and more RAY_UPDATE_BUFFER rays.
   */
  
  #ifdef __BRANCHED_PATH__
  ccl_device_inline void kernel_split_branched_indirect_light_init(KernelGlobals *kg, int ray_index)
  {
    kernel_split_branched_path_indirect_loop_init(kg, ray_index);
  
    ADD_RAY_FLAG(kernel_split_state.ray_state, ray_index, RAY_BRANCHED_LIGHT_INDIRECT);
  }
  
  ccl_device void kernel_split_branched_transparent_bounce(KernelGlobals *kg, int ray_index)
  {
    ccl_global float3 *throughput = &kernel_split_state.throughput[ray_index];
    ShaderData *sd = kernel_split_sd(sd, ray_index);
    ccl_global PathState *state = &kernel_split_state.path_state[ray_index];
    ccl_global Ray *ray = &kernel_split_state.ray[ray_index];
  
  #  ifdef __VOLUME__
    if (!(sd->flag & SD_HAS_ONLY_VOLUME)) {
  #  endif
      /* continue in case of transparency */
      *throughput *= shader_bsdf_transparency(kg, sd);
  
      if (is_zero(*throughput)) {
        kernel_split_path_end(kg, ray_index);
        return;
      }
  
      /* Update Path State */
      path_state_next(kg, state, LABEL_TRANSPARENT);
  #  ifdef __VOLUME__
    }
    else {
      if (!path_state_volume_next(kg, state)) {
        kernel_split_path_end(kg, ray_index);
        return;
      }
    }
  #  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__ */
  }
  #endif /* __BRANCHED_PATH__ */
  
  ccl_device void kernel_next_iteration_setup(KernelGlobals *kg,
                                              ccl_local_param unsigned int *local_queue_atomics)
  {
    if (ccl_local_id(0) == 0 && ccl_local_id(1) == 0) {
      *local_queue_atomics = 0;
    }
    ccl_barrier(CCL_LOCAL_MEM_FENCE);
  
    if (ccl_global_id(0) == 0 && ccl_global_id(1) == 0) {
      /* If we are here, then it means that scene-intersect kernel
      * has already been executed atleast once. From the next time,
      * scene-intersect kernel may operate on queues to fetch ray index
      */
      *kernel_split_params.use_queues_flag = 1;
  
      /* Mark queue indices of QUEUE_SHADOW_RAY_CAST_AO_RAYS and
       * QUEUE_SHADOW_RAY_CAST_DL_RAYS queues that were made empty during the
       * previous kernel.
       */
      kernel_split_params.queue_index[QUEUE_SHADOW_RAY_CAST_AO_RAYS] = 0;
      kernel_split_params.queue_index[QUEUE_SHADOW_RAY_CAST_DL_RAYS] = 0;
    }
  
    int ray_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
    ray_index = get_ray_index(kg,
                              ray_index,
                              QUEUE_ACTIVE_AND_REGENERATED_RAYS,
                              kernel_split_state.queue_data,
                              kernel_split_params.queue_size,
                              0);
  
    ccl_global char *ray_state = kernel_split_state.ray_state;
  
  #ifdef __VOLUME__
    /* Reactivate only volume rays here, most surface work was skipped. */
    if (IS_STATE(ray_state, ray_index, RAY_HAS_ONLY_VOLUME)) {
      ASSIGN_RAY_STATE(ray_state, ray_index, RAY_ACTIVE);
    }
  #endif
  
    bool active = IS_STATE(ray_state, ray_index, RAY_ACTIVE);
    if (active) {
      ccl_global float3 *throughput = &kernel_split_state.throughput[ray_index];
      ccl_global Ray *ray = &kernel_split_state.ray[ray_index];
      ShaderData *sd = kernel_split_sd(sd, ray_index);
      ccl_global PathState *state = &kernel_split_state.path_state[ray_index];
      PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
  
  #ifdef __BRANCHED_PATH__
      if (!kernel_data.integrator.branched || IS_FLAG(ray_state, ray_index, RAY_BRANCHED_INDIRECT)) {
  #endif
        /* Compute direct lighting and next bounce. */
        if (!kernel_path_surface_bounce(kg, sd, throughput, state, &L->state, ray)) {
          kernel_split_path_end(kg, ray_index);
        }
  #ifdef __BRANCHED_PATH__
      }
      else if (sd->flag & SD_HAS_ONLY_VOLUME) {
        kernel_split_branched_transparent_bounce(kg, ray_index);
      }
      else {
        kernel_split_branched_indirect_light_init(kg, ray_index);
  
        if (kernel_split_branched_path_surface_indirect_light_iter(
                kg, ray_index, 1.0f, kernel_split_sd(branched_state_sd, ray_index), true, true)) {
          ASSIGN_RAY_STATE(ray_state, ray_index, RAY_REGENERATED);
        }
        else {
          kernel_split_branched_path_indirect_loop_end(kg, ray_index);
          kernel_split_branched_transparent_bounce(kg, ray_index);
        }
      }
  #endif /* __BRANCHED_PATH__ */
    }
  
    /* Enqueue RAY_UPDATE_BUFFER rays. */
    enqueue_ray_index_local(ray_index,
                            QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS,
                            IS_STATE(ray_state, ray_index, RAY_UPDATE_BUFFER) && active,
                            kernel_split_params.queue_size,
                            local_queue_atomics,
                            kernel_split_state.queue_data,
                            kernel_split_params.queue_index);
  
  #ifdef __BRANCHED_PATH__
    /* iter loop */
    if (ccl_global_id(0) == 0 && ccl_global_id(1) == 0) {
      kernel_split_params.queue_index[QUEUE_LIGHT_INDIRECT_ITER] = 0;
    }
  
    ray_index = get_ray_index(kg,
                              ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0),
                              QUEUE_LIGHT_INDIRECT_ITER,
                              kernel_split_state.queue_data,
                              kernel_split_params.queue_size,
                              1);
  
    if (IS_STATE(ray_state, ray_index, RAY_LIGHT_INDIRECT_NEXT_ITER)) {
      /* for render passes, sum and reset indirect light pass variables
       * for the next samples */
      PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
  
      path_radiance_sum_indirect(L);
      path_radiance_reset_indirect(L);
  
      if (kernel_split_branched_path_surface_indirect_light_iter(
              kg, ray_index, 1.0f, kernel_split_sd(branched_state_sd, ray_index), true, true)) {
        ASSIGN_RAY_STATE(ray_state, ray_index, RAY_REGENERATED);
      }
      else {
        kernel_split_branched_path_indirect_loop_end(kg, ray_index);
        kernel_split_branched_transparent_bounce(kg, ray_index);
      }
    }
  
  #  ifdef __VOLUME__
    /* Enqueue RAY_VOLUME_INDIRECT_NEXT_ITER rays */
    ccl_barrier(CCL_LOCAL_MEM_FENCE);
    if (ccl_local_id(0) == 0 && ccl_local_id(1) == 0) {
      *local_queue_atomics = 0;
    }
    ccl_barrier(CCL_LOCAL_MEM_FENCE);
  
    ray_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
    enqueue_ray_index_local(
        ray_index,
        QUEUE_VOLUME_INDIRECT_ITER,
        IS_STATE(kernel_split_state.ray_state, ray_index, RAY_VOLUME_INDIRECT_NEXT_ITER),
        kernel_split_params.queue_size,
        local_queue_atomics,
        kernel_split_state.queue_data,
        kernel_split_params.queue_index);
  
  #  endif /* __VOLUME__ */
  
  #  ifdef __SUBSURFACE__
    /* Enqueue RAY_SUBSURFACE_INDIRECT_NEXT_ITER rays */
    ccl_barrier(CCL_LOCAL_MEM_FENCE);
    if (ccl_local_id(0) == 0 && ccl_local_id(1) == 0) {
      *local_queue_atomics = 0;
    }
    ccl_barrier(CCL_LOCAL_MEM_FENCE);
  
    ray_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
    enqueue_ray_index_local(
        ray_index,
        QUEUE_SUBSURFACE_INDIRECT_ITER,
        IS_STATE(kernel_split_state.ray_state, ray_index, RAY_SUBSURFACE_INDIRECT_NEXT_ITER),
        kernel_split_params.queue_size,
        local_queue_atomics,
        kernel_split_state.queue_data,
        kernel_split_params.queue_index);
  #  endif /* __SUBSURFACE__ */
  #endif   /* __BRANCHED_PATH__ */
  }
  
  CCL_NAMESPACE_END
  