Cycles: Restructure kernel files organization

Since the kernel split work we're now having quite a few of new files, majority
of which are related on the kernel entry points. Keeping those files in the
root kernel folder will eventually make it really hard to follow which files are
actual implementation of Cycles kernel.

Those files are now moved to kernel/kernels/<device_type>. This way adding extra
entry points will be less noisy. It is also nice to have all device-specific
files grouped together.

Another change is in the way how split kernel invokes logic. Previously all the
logic was implemented directly in the .cl files, which makes it a bit tricky to
re-use the logic across other devices. Since we'll likely be looking into doing
same split work for CUDA devices eventually it makes sense to move logic from
.cl files to header files. Those files are stored in kernel/split. This does not
mean the header files will not give error messages when tried to be included
from other devices and their arguments will likely be changed, but having such
separation is a good start anyway.

There should be no functional changes.

Reviewers: juicyfruit, dingto

Differential Revision: https://developer.blender.org/D1314

1 files changed, 283 insertions, 0 deletions

diff --git a/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
new file mode 100644
index 00000000000..393ea4bcadc
--- /dev/null
+++ b/intern/cycles/kernel/split/kernel_holdout_emission_blurring_pathtermination_ao.h
@@ -0,0 +1,283 @@
+/*
+ * 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.
+ */
+
+#include "kernel_split_common.h"
+
+/*
+ * Note on kernel_holdout_emission_blurring_pathtermination_ao kernel.
+ * This is the sixth kernel in the ray tracing logic. This is the fifth
+ * of the path iteration kernels. This kernel takes care of the logic to process
+ * "material of type holdout", indirect primitive emission, bsdf blurring,
+ * probabilistic path termination and AO.
+ *
+ * This kernels determines the rays for which a shadow_blocked() function associated with AO should be executed.
+ * Those rays for which a shadow_blocked() function for AO must be executed are marked with flag RAY_SHADOW_RAY_CAST_ao and
+ * enqueued into the queue QUEUE_SHADOW_RAY_CAST_AO_RAYS
+ *
+ * Ray state of rays that are terminated in this kernel are changed to RAY_UPDATE_BUFFER
+ *
+ * The input and output are as follows,
+ *
+ * rng_coop ---------------------------------------------|--- kernel_holdout_emission_blurring_pathtermination_ao ---|--- Queue_index (QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS)
+ * throughput_coop --------------------------------------|                                                           |--- PathState_coop
+ * PathRadiance_coop ------------------------------------|                                                           |--- throughput_coop
+ * Intersection_coop ------------------------------------|                                                           |--- L_transparent_coop
+ * PathState_coop ---------------------------------------|                                                           |--- per_sample_output_buffers
+ * L_transparent_coop -----------------------------------|                                                           |--- PathRadiance_coop
+ * shader_data ------------------------------------------|                                                           |--- ShaderData
+ * ray_state --------------------------------------------|                                                           |--- ray_state
+ * Queue_data (QUEUE_ACTIVE_AND_REGENERATED_RAYS) -------|                                                           |--- Queue_data (QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS)
+ * Queue_index (QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS) ---|                                                           |--- AOAlpha_coop
+ * kg (globals + data) ----------------------------------|                                                           |--- AOBSDF_coop
+ * parallel_samples -------------------------------------|                                                           |--- AOLightRay_coop
+ * per_sample_output_buffers ----------------------------|                                                           |
+ * sw ---------------------------------------------------|                                                           |
+ * sh ---------------------------------------------------|                                                           |
+ * sx ---------------------------------------------------|                                                           |
+ * sy ---------------------------------------------------|                                                           |
+ * stride -----------------------------------------------|                                                           |
+ * work_array -------------------------------------------|                                                           |
+ * queuesize --------------------------------------------|                                                           |
+ * start_sample -----------------------------------------|                                                           |
+ *
+ * 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_BUFFER
+ * 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_BUFFER, 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 and RAY_REGENERATED rays
+ * QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be filled with RAY_TO_REGENERATE rays.
+ * QUEUE_SHADOW_RAY_CAST_AO_RAYS will be empty.
+ * At exit,
+ * QUEUE_ACTIVE_AND_REGENERATED_RAYS will be filled with RAY_ACTIVE, RAY_REGENERATED and RAY_UPDATE_BUFFER rays
+ * QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be filled with RAY_TO_REGENERATE and RAY_UPDATE_BUFFER rays
+ * QUEUE_SHADOW_RAY_CAST_AO_RAYS will be filled with rays marked with flag RAY_SHADOW_RAY_CAST_AO
+ */
+
+ccl_device void kernel_holdout_emission_blurring_pathtermination_ao(
+	ccl_global char *globals,
+	ccl_constant KernelData *data,
+	ccl_global char *shader_data,               /* Required throughout the kernel except probabilistic path termination and AO */
+	ccl_global float *per_sample_output_buffers,
+	ccl_global uint *rng_coop,                  /* Required for "kernel_write_data_passes" and AO */
+	ccl_global float3 *throughput_coop,         /* Required for handling holdout material and AO */
+	ccl_global float *L_transparent_coop,       /* Required for handling holdout material */
+	PathRadiance *PathRadiance_coop, /* Required for "kernel_write_data_passes" and indirect primitive emission */
+	ccl_global PathState *PathState_coop,       /* Required throughout the kernel and AO */
+	Intersection *Intersection_coop, /* Required for indirect primitive emission */
+	ccl_global float3 *AOAlpha_coop,            /* Required for AO */
+	ccl_global float3 *AOBSDF_coop,             /* Required for AO */
+	ccl_global Ray *AOLightRay_coop,            /* Required for AO */
+	int sw, int sh, int sx, int sy, int stride,
+	ccl_global char *ray_state,                /* Denotes the state of each ray */
+	ccl_global unsigned int *work_array,       /* Denotes the work that each ray belongs to */
+	ccl_global int *Queue_data,                /* Queue memory */
+	ccl_global int *Queue_index,               /* Tracks the number of elements in each queue */
+	int queuesize,                             /* Size (capacity) of each queue */
+#ifdef __WORK_STEALING__
+	unsigned int start_sample,
+#endif
+	int parallel_samples                       /* Number of samples to be processed in parallel */
+	)
+{
+	ccl_local unsigned int local_queue_atomics_bg;
+	ccl_local unsigned int local_queue_atomics_ao;
+	if(get_local_id(0) == 0 && get_local_id(1) == 0) {
+		local_queue_atomics_bg = 0;
+		local_queue_atomics_ao = 0;
+	}
+	barrier(CLK_LOCAL_MEM_FENCE);
+
+	char enqueue_flag = 0;
+	char enqueue_flag_AO_SHADOW_RAY_CAST = 0;
+	int ray_index = get_global_id(1) * get_global_size(0) + get_global_id(0);
+	ray_index = get_ray_index(ray_index, QUEUE_ACTIVE_AND_REGENERATED_RAYS, Queue_data, queuesize, 0);
+
+#ifdef __COMPUTE_DEVICE_GPU__
+	/* If we are executing on a GPU device, we exit all threads that are not required
+	 * If we are executing on a CPU device, then we need to keep all threads active
+	 * since we have barrier() calls later in the kernel. CPU devices
+	 * expect all threads to execute barrier statement.
+	 */
+	if(ray_index == QUEUE_EMPTY_SLOT)
+		return;
+#endif
+
+#ifndef __COMPUTE_DEVICE_GPU__
+	if(ray_index != QUEUE_EMPTY_SLOT) {
+#endif
+		/* Load kernel globals structure and ShaderData structure */
+		KernelGlobals *kg = (KernelGlobals *)globals;
+		ShaderData *sd = (ShaderData *)shader_data;
+
+#ifdef __WORK_STEALING__
+		unsigned int my_work;
+		unsigned int pixel_x;
+		unsigned int pixel_y;
+#endif
+		unsigned int tile_x;
+		unsigned int tile_y;
+		int my_sample_tile;
+		unsigned int sample;
+
+		ccl_global RNG *rng = 0x0;
+		ccl_global PathState *state = 0x0;
+		float3 throughput;
+
+		if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
+
+			throughput = throughput_coop[ray_index];
+			state = &PathState_coop[ray_index];
+			rng = &rng_coop[ray_index];
+#ifdef __WORK_STEALING__
+			my_work = work_array[ray_index];
+			sample = get_my_sample(my_work, sw, sh, parallel_samples, ray_index) + start_sample;
+			get_pixel_tile_position(&pixel_x, &pixel_y, &tile_x, &tile_y, my_work, sw, sh, sx, sy, parallel_samples, ray_index);
+			my_sample_tile = 0;
+#else // __WORK_STEALING__
+			sample = work_array[ray_index];
+			/* buffer's stride is "stride"; Find x and y using ray_index */
+			int tile_index = ray_index / parallel_samples;
+			tile_x = tile_index % sw;
+			tile_y = tile_index / sw;
+			my_sample_tile = ray_index - (tile_index * parallel_samples);
+#endif // __WORK_STEALING__
+			per_sample_output_buffers += (((tile_x + (tile_y * stride)) * parallel_samples) + my_sample_tile) * kernel_data.film.pass_stride;
+
+			/* holdout */
+#ifdef __HOLDOUT__
+			if((ccl_fetch(sd, flag) & (SD_HOLDOUT|SD_HOLDOUT_MASK)) && (state->flag & PATH_RAY_CAMERA)) {
+				if(kernel_data.background.transparent) {
+					float3 holdout_weight;
+
+					if(ccl_fetch(sd, flag) & SD_HOLDOUT_MASK)
+						holdout_weight = make_float3(1.0f, 1.0f, 1.0f);
+					else
+						holdout_weight = shader_holdout_eval(kg, sd);
+
+					/* any throughput is ok, should all be identical here */
+					L_transparent_coop[ray_index] += average(holdout_weight*throughput);
+				}
+
+				if(ccl_fetch(sd, flag) & SD_HOLDOUT_MASK) {
+					ASSIGN_RAY_STATE(ray_state, ray_index, RAY_UPDATE_BUFFER);
+					enqueue_flag = 1;
+				}
+			}
+#endif
+		}
+
+		if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
+
+			PathRadiance *L = &PathRadiance_coop[ray_index];
+			/* holdout mask objects do not write data passes */
+			kernel_write_data_passes(kg, per_sample_output_buffers, L, sd, sample, state, throughput);
+
+			/* blurring of bsdf after bounces, for rays that have a small likelihood
+				* of following this particular path (diffuse, rough glossy) */
+			if(kernel_data.integrator.filter_glossy != FLT_MAX) {
+				float blur_pdf = kernel_data.integrator.filter_glossy*state->min_ray_pdf;
+
+				if(blur_pdf < 1.0f) {
+					float blur_roughness = sqrtf(1.0f - blur_pdf)*0.5f;
+					shader_bsdf_blur(kg, sd, blur_roughness);
+				}
+			}
+
+#ifdef __EMISSION__
+			/* emission */
+			if(ccl_fetch(sd, flag) & SD_EMISSION) {
+				/* todo: is isect.t wrong here for transparent surfaces? */
+				float3 emission = indirect_primitive_emission(kg, sd, Intersection_coop[ray_index].t, state->flag, state->ray_pdf);
+				path_radiance_accum_emission(L, throughput, emission, state->bounce);
+			}
+#endif
+
+			/* 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_terminate_probability(kg, state, throughput);
+
+			if(probability == 0.0f) {
+				ASSIGN_RAY_STATE(ray_state, ray_index, RAY_UPDATE_BUFFER);
+				enqueue_flag = 1;
+			}
+
+			if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
+				if(probability != 1.0f) {
+					float terminate = path_state_rng_1D_for_decision(kg, rng, state, PRNG_TERMINATE);
+
+					if(terminate >= probability) {
+						ASSIGN_RAY_STATE(ray_state, ray_index, RAY_UPDATE_BUFFER);
+						enqueue_flag = 1;
+					} else {
+						throughput_coop[ray_index] = throughput/probability;
+					}
+				}
+			}
+		}
+
+#ifdef __AO__
+		if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
+			/* ambient occlusion */
+			if(kernel_data.integrator.use_ambient_occlusion || (ccl_fetch(sd, flag) & SD_AO)) {
+				/* todo: solve correlation */
+				float bsdf_u, bsdf_v;
+				path_state_rng_2D(kg, rng, state, PRNG_BSDF_U, &bsdf_u, &bsdf_v);
+
+				float ao_factor = kernel_data.background.ao_factor;
+				float3 ao_N;
+				AOBSDF_coop[ray_index] = shader_bsdf_ao(kg, sd, ao_factor, &ao_N);
+				AOAlpha_coop[ray_index] = shader_bsdf_alpha(kg, sd);
+
+				float3 ao_D;
+				float ao_pdf;
+				sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
+
+				if(dot(ccl_fetch(sd, Ng), ao_D) > 0.0f && ao_pdf != 0.0f) {
+					Ray _ray;
+					_ray.P = ray_offset(ccl_fetch(sd, P), ccl_fetch(sd, Ng));
+					_ray.D = ao_D;
+					_ray.t = kernel_data.background.ao_distance;
+#ifdef __OBJECT_MOTION__
+					_ray.time = ccl_fetch(sd, time);
+#endif
+					_ray.dP = ccl_fetch(sd, dP);
+					_ray.dD = differential3_zero();
+					AOLightRay_coop[ray_index] = _ray;
+
+					ADD_RAY_FLAG(ray_state, ray_index, RAY_SHADOW_RAY_CAST_AO);
+					enqueue_flag_AO_SHADOW_RAY_CAST = 1;
+				}
+			}
+		}
+#endif
+#ifndef __COMPUTE_DEVICE_GPU__
+	}
+#endif
+
+	/* Enqueue RAY_UPDATE_BUFFER rays */
+	enqueue_ray_index_local(ray_index, QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS, enqueue_flag, queuesize, &local_queue_atomics_bg, Queue_data, Queue_index);
+#ifdef __AO__
+	/* Enqueue to-shadow-ray-cast rays */
+	enqueue_ray_index_local(ray_index, QUEUE_SHADOW_RAY_CAST_AO_RAYS, enqueue_flag_AO_SHADOW_RAY_CAST, queuesize, &local_queue_atomics_ao, Queue_data, Queue_index);
+#endif
+}