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, 138 insertions, 0 deletions

diff --git a/intern/cycles/kernel/split/kernel_direct_lighting.h b/intern/cycles/kernel/split/kernel_direct_lighting.h
new file mode 100644
index 00000000000..6b83d892057
--- /dev/null
+++ b/intern/cycles/kernel/split/kernel_direct_lighting.h
@@ -0,0 +1,138 @@
+/*
+ * 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_direct_lighting kernel.
+ * This is the eighth kernel in the ray tracing logic. This is the seventh
+ * of the path iteration kernels. This kernel takes care of direct lighting
+ * logic. However, the "shadow ray cast" part of direct lighting is handled
+ * in the next kernel.
+ *
+ * This kernels determines the rays for which a shadow_blocked() function associated with direct lighting should be executed.
+ * Those rays for which a shadow_blocked() function for direct-lighting must be executed, are marked with flag RAY_SHADOW_RAY_CAST_DL and
+ * enqueued into the queue QUEUE_SHADOW_RAY_CAST_DL_RAYS
+ *
+ * The input and output are as follows,
+ *
+ * rng_coop -----------------------------------------|--- kernel_direct_lighting --|--- BSDFEval_coop
+ * PathState_coop -----------------------------------|                             |--- ISLamp_coop
+ * shader_data --------------------------------------|                             |--- LightRay_coop
+ * ray_state ----------------------------------------|                             |--- ray_state
+ * Queue_data (QUEUE_ACTIVE_AND_REGENERATED_RAYS) ---|                             |
+ * kg (globals + data) ------------------------------|                             |
+ * queuesize ----------------------------------------|                             |
+ *
+ * note on shader_DL : shader_DL is neither input nor output to this kernel; shader_DL is filled and consumed in this kernel itself.
+ * Note on Queues :
+ * This kernel only reads from the QUEUE_ACTIVE_AND_REGENERATED_RAYS queue and processes
+ * only the rays of state RAY_ACTIVE; If a ray needs to execute the corresponding shadow_blocked
+ * part, after direct lighting, the ray is marked with RAY_SHADOW_RAY_CAST_DL flag.
+ *
+ * State of queues when this kernel is called :
+ * state of queues QUEUE_ACTIVE_AND_REGENERATED_RAYS and QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS will be same
+ * before and after this kernel call.
+ * QUEUE_SHADOW_RAY_CAST_DL_RAYS queue will be filled with rays for which a shadow_blocked function must be executed, after this
+ * kernel call. Before this kernel call the QUEUE_SHADOW_RAY_CAST_DL_RAYS will be empty.
+ */
+ccl_device void kernel_direct_lighting(
+	ccl_global char *globals,
+	ccl_constant KernelData *data,
+	ccl_global char *shader_data,           /* Required for direct lighting */
+	ccl_global char *shader_DL,             /* Required for direct lighting */
+	ccl_global uint *rng_coop,              /* Required for direct lighting */
+	ccl_global PathState *PathState_coop,   /* Required for direct lighting */
+	ccl_global int *ISLamp_coop,            /* Required for direct lighting */
+	ccl_global Ray *LightRay_coop,          /* Required for direct lighting */
+	ccl_global BsdfEval *BSDFEval_coop,     /* Required for direct lighting */
+	ccl_global char *ray_state,             /* Denotes the state of each ray */
+	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 */
+	)
+{
+	ccl_local unsigned int local_queue_atomics;
+	if(get_local_id(0) == 0 && get_local_id(1) == 0) {
+		local_queue_atomics = 0;
+	}
+	barrier(CLK_LOCAL_MEM_FENCE);
+
+	char enqueue_flag = 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
+		if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
+			/* Load kernel globals structure and ShaderData structure */
+			KernelGlobals *kg = (KernelGlobals *)globals;
+			ShaderData *sd = (ShaderData *)shader_data;
+			ShaderData *sd_DL  = (ShaderData *)shader_DL;
+
+			ccl_global PathState *state = &PathState_coop[ray_index];
+
+			/* direct lighting */
+#ifdef __EMISSION__
+			if((kernel_data.integrator.use_direct_light && (ccl_fetch(sd, flag) & SD_BSDF_HAS_EVAL))) {
+				/* sample illumination from lights to find path contribution */
+				ccl_global RNG* rng = &rng_coop[ray_index];
+				float light_t = path_state_rng_1D(kg, rng, state, PRNG_LIGHT);
+				float light_u, light_v;
+				path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
+
+				LightSample ls;
+				light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls);
+
+				Ray light_ray;
+#ifdef __OBJECT_MOTION__
+				light_ray.time = ccl_fetch(sd, time);
+#endif
+
+				BsdfEval L_light;
+				bool is_lamp;
+				if(direct_emission(kg, sd, &ls, &light_ray, &L_light, &is_lamp, state->bounce, state->transparent_bounce, sd_DL)) {
+					/* write intermediate data to global memory to access from the next kernel */
+					LightRay_coop[ray_index] = light_ray;
+					BSDFEval_coop[ray_index] = L_light;
+					ISLamp_coop[ray_index] = is_lamp;
+					/// mark ray state for next shadow kernel
+					ADD_RAY_FLAG(ray_state, ray_index, RAY_SHADOW_RAY_CAST_DL);
+					enqueue_flag = 1;
+				}
+			}
+#endif
+		}
+#ifndef __COMPUTE_DEVICE_GPU__
+	}
+#endif
+
+#ifdef __EMISSION__
+	/* Enqueue RAY_SHADOW_RAY_CAST_DL rays */
+	enqueue_ray_index_local(ray_index, QUEUE_SHADOW_RAY_CAST_DL_RAYS, enqueue_flag, queuesize, &local_queue_atomics, Queue_data, Queue_index);
+#endif
+}