intern/cycles/kernel/split/kernel_direct_lighting.h

   1 /*
   2  * Copyright 2011-2015 Blender Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "kernel_split_common.h"
  18
  19 /* Note on kernel_direct_lighting kernel.
  20  * This is the eighth kernel in the ray tracing logic. This is the seventh
  21  * of the path iteration kernels. This kernel takes care of direct lighting
  22  * logic. However, the "shadow ray cast" part of direct lighting is handled
  23  * in the next kernel.
  24  *
  25  * This kernels determines the rays for which a shadow_blocked() function associated with direct lighting should be executed.
  26  * Those rays for which a shadow_blocked() function for direct-lighting must be executed, are marked with flag RAY_SHADOW_RAY_CAST_DL and
  27  * enqueued into the queue QUEUE_SHADOW_RAY_CAST_DL_RAYS
  28  *
  29  * The input and output are as follows,
  30  *
  31  * rng_coop -----------------------------------------|--- kernel_direct_lighting --|--- BSDFEval_coop
  32  * PathState_coop -----------------------------------|                             |--- ISLamp_coop
  33  * sd -----------------------------------------------|                             |--- LightRay_coop
  34  * ray_state ----------------------------------------|                             |--- ray_state
  35  * Queue_data (QUEUE_ACTIVE_AND_REGENERATED_RAYS) ---|                             |
  36  * kg (globals) -------------------------------------|                             |
  37  * queuesize ----------------------------------------|                             |
  38  *
  39  * note on sd_DL : sd_DL is neither input nor output to this kernel; sd_DL is filled and consumed in this kernel itself.
  40  * Note on Queues :
  41  * This kernel only reads from the QUEUE_ACTIVE_AND_REGENERATED_RAYS queue and processes
  42  * only the rays of state RAY_ACTIVE; If a ray needs to execute the corresponding shadow_blocked
  43  * part, after direct lighting, the ray is marked with RAY_SHADOW_RAY_CAST_DL flag.
  44  *
  45  * State of queues when this kernel is called :
  46  * state of queues QUEUE_ACTIVE_AND_REGENERATED_RAYS and QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be same
  47  * before and after this kernel call.
  48  * QUEUE_SHADOW_RAY_CAST_DL_RAYS queue will be filled with rays for which a shadow_blocked function must be executed, after this
  49  * kernel call. Before this kernel call the QUEUE_SHADOW_RAY_CAST_DL_RAYS will be empty.
  50  */
  51 ccl_device char kernel_direct_lighting(
  52         KernelGlobals *kg,
  53         ShaderData *sd,                         /* Required for direct lighting */
  54         ShaderData *sd_DL,                      /* Required for direct lighting */
  55         ccl_global uint *rng_coop,              /* Required for direct lighting */
  56         ccl_global PathState *PathState_coop,   /* Required for direct lighting */
  57         ccl_global int *ISLamp_coop,            /* Required for direct lighting */
  58         ccl_global Ray *LightRay_coop,          /* Required for direct lighting */
  59         ccl_global BsdfEval *BSDFEval_coop,     /* Required for direct lighting */
  60         ccl_global char *ray_state,             /* Denotes the state of each ray */
  61         int ray_index)
  62 {
  63         char enqueue_flag = 0;
  64         if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
  65                 ccl_global PathState *state = &PathState_coop[ray_index];
  66
  67                 /* direct lighting */
  68 #ifdef __EMISSION__
  69                 if((kernel_data.integrator.use_direct_light &&
  70                     (ccl_fetch(sd, flag) & SD_BSDF_HAS_EVAL)))
  71                 {
  72                         /* Sample illumination from lights to find path contribution. */
  73                         ccl_global RNG* rng = &rng_coop[ray_index];
  74                         float light_t = path_state_rng_1D(kg, rng, state, PRNG_LIGHT);
  75                         float light_u, light_v;
  76                         path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
  77
  78                         LightSample ls;
  79                         light_sample(kg,
  80                                      light_t, light_u, light_v,
  81                                      ccl_fetch(sd, time),
  82                                      ccl_fetch(sd, P),
  83                                      state->bounce,
  84                                      &ls);
  85
  86                         Ray light_ray;
  87 #ifdef __OBJECT_MOTION__
  88                         light_ray.time = ccl_fetch(sd, time);
  89 #endif
  90
  91                         BsdfEval L_light;
  92                         bool is_lamp;
  93                         if(direct_emission(kg, sd, &ls, state, &light_ray, &L_light, &is_lamp,
  94                                            sd_DL))
  95                         {
  96                                 /* Write intermediate data to global memory to access from
  97                                  * the next kernel.
  98                                  */
  99                                 LightRay_coop[ray_index] = light_ray;
 100                                 BSDFEval_coop[ray_index] = L_light;
 101                                 ISLamp_coop[ray_index] = is_lamp;
 102                                 /* Mark ray state for next shadow kernel. */
 103                                 ADD_RAY_FLAG(ray_state, ray_index, RAY_SHADOW_RAY_CAST_DL);
 104                                 enqueue_flag = 1;
 105                         }
 106                 }
 107 #endif  /* __EMISSION__ */
 108         }
 109         return enqueue_flag;
 110 }