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, 273 insertions, 0 deletions

diff --git a/intern/cycles/kernel/integrator/integrator_state_util.h b/intern/cycles/kernel/integrator/integrator_state_util.h
new file mode 100644
index 00000000000..cdf412fe22f
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_state_util.h
@@ -0,0 +1,273 @@
+/*
+ * Copyright 2011-2021 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.
+ */
+
+#pragma once
+
+#include "kernel/integrator/integrator_state.h"
+#include "kernel/kernel_differential.h"
+
+CCL_NAMESPACE_BEGIN
+
+/* Ray */
+
+ccl_device_forceinline void integrator_state_write_ray(INTEGRATOR_STATE_ARGS,
+                                                       const Ray *ccl_restrict ray)
+{
+  INTEGRATOR_STATE_WRITE(ray, P) = ray->P;
+  INTEGRATOR_STATE_WRITE(ray, D) = ray->D;
+  INTEGRATOR_STATE_WRITE(ray, t) = ray->t;
+  INTEGRATOR_STATE_WRITE(ray, time) = ray->time;
+  INTEGRATOR_STATE_WRITE(ray, dP) = ray->dP;
+  INTEGRATOR_STATE_WRITE(ray, dD) = ray->dD;
+}
+
+ccl_device_forceinline void integrator_state_read_ray(INTEGRATOR_STATE_CONST_ARGS,
+                                                      Ray *ccl_restrict ray)
+{
+  ray->P = INTEGRATOR_STATE(ray, P);
+  ray->D = INTEGRATOR_STATE(ray, D);
+  ray->t = INTEGRATOR_STATE(ray, t);
+  ray->time = INTEGRATOR_STATE(ray, time);
+  ray->dP = INTEGRATOR_STATE(ray, dP);
+  ray->dD = INTEGRATOR_STATE(ray, dD);
+}
+
+/* Shadow Ray */
+
+ccl_device_forceinline void integrator_state_write_shadow_ray(INTEGRATOR_STATE_ARGS,
+                                                              const Ray *ccl_restrict ray)
+{
+  INTEGRATOR_STATE_WRITE(shadow_ray, P) = ray->P;
+  INTEGRATOR_STATE_WRITE(shadow_ray, D) = ray->D;
+  INTEGRATOR_STATE_WRITE(shadow_ray, t) = ray->t;
+  INTEGRATOR_STATE_WRITE(shadow_ray, time) = ray->time;
+  INTEGRATOR_STATE_WRITE(shadow_ray, dP) = ray->dP;
+}
+
+ccl_device_forceinline void integrator_state_read_shadow_ray(INTEGRATOR_STATE_CONST_ARGS,
+                                                             Ray *ccl_restrict ray)
+{
+  ray->P = INTEGRATOR_STATE(shadow_ray, P);
+  ray->D = INTEGRATOR_STATE(shadow_ray, D);
+  ray->t = INTEGRATOR_STATE(shadow_ray, t);
+  ray->time = INTEGRATOR_STATE(shadow_ray, time);
+  ray->dP = INTEGRATOR_STATE(shadow_ray, dP);
+  ray->dD = differential_zero_compact();
+}
+
+/* Intersection */
+
+ccl_device_forceinline void integrator_state_write_isect(INTEGRATOR_STATE_ARGS,
+                                                         const Intersection *ccl_restrict isect)
+{
+  INTEGRATOR_STATE_WRITE(isect, t) = isect->t;
+  INTEGRATOR_STATE_WRITE(isect, u) = isect->u;
+  INTEGRATOR_STATE_WRITE(isect, v) = isect->v;
+  INTEGRATOR_STATE_WRITE(isect, object) = isect->object;
+  INTEGRATOR_STATE_WRITE(isect, prim) = isect->prim;
+  INTEGRATOR_STATE_WRITE(isect, type) = isect->type;
+#ifdef __EMBREE__
+  INTEGRATOR_STATE_WRITE(isect, Ng) = isect->Ng;
+#endif
+}
+
+ccl_device_forceinline void integrator_state_read_isect(INTEGRATOR_STATE_CONST_ARGS,
+                                                        Intersection *ccl_restrict isect)
+{
+  isect->prim = INTEGRATOR_STATE(isect, prim);
+  isect->object = INTEGRATOR_STATE(isect, object);
+  isect->type = INTEGRATOR_STATE(isect, type);
+  isect->u = INTEGRATOR_STATE(isect, u);
+  isect->v = INTEGRATOR_STATE(isect, v);
+  isect->t = INTEGRATOR_STATE(isect, t);
+#ifdef __EMBREE__
+  isect->Ng = INTEGRATOR_STATE(isect, Ng);
+#endif
+}
+
+ccl_device_forceinline VolumeStack integrator_state_read_volume_stack(INTEGRATOR_STATE_CONST_ARGS,
+                                                                      int i)
+{
+  VolumeStack entry = {INTEGRATOR_STATE_ARRAY(volume_stack, i, object),
+                       INTEGRATOR_STATE_ARRAY(volume_stack, i, shader)};
+  return entry;
+}
+
+ccl_device_forceinline void integrator_state_write_volume_stack(INTEGRATOR_STATE_ARGS,
+                                                                int i,
+                                                                VolumeStack entry)
+{
+  INTEGRATOR_STATE_ARRAY_WRITE(volume_stack, i, object) = entry.object;
+  INTEGRATOR_STATE_ARRAY_WRITE(volume_stack, i, shader) = entry.shader;
+}
+
+ccl_device_forceinline bool integrator_state_volume_stack_is_empty(INTEGRATOR_STATE_CONST_ARGS)
+{
+  return (kernel_data.kernel_features & KERNEL_FEATURE_VOLUME) ?
+             INTEGRATOR_STATE_ARRAY(volume_stack, 0, shader) == SHADER_NONE :
+             true;
+}
+
+/* Shadow Intersection */
+
+ccl_device_forceinline void integrator_state_write_shadow_isect(
+    INTEGRATOR_STATE_ARGS, const Intersection *ccl_restrict isect, const int index)
+{
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, t) = isect->t;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, u) = isect->u;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, v) = isect->v;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, object) = isect->object;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, prim) = isect->prim;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, type) = isect->type;
+#ifdef __EMBREE__
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_isect, index, Ng) = isect->Ng;
+#endif
+}
+
+ccl_device_forceinline void integrator_state_read_shadow_isect(INTEGRATOR_STATE_CONST_ARGS,
+                                                               Intersection *ccl_restrict isect,
+                                                               const int index)
+{
+  isect->prim = INTEGRATOR_STATE_ARRAY(shadow_isect, index, prim);
+  isect->object = INTEGRATOR_STATE_ARRAY(shadow_isect, index, object);
+  isect->type = INTEGRATOR_STATE_ARRAY(shadow_isect, index, type);
+  isect->u = INTEGRATOR_STATE_ARRAY(shadow_isect, index, u);
+  isect->v = INTEGRATOR_STATE_ARRAY(shadow_isect, index, v);
+  isect->t = INTEGRATOR_STATE_ARRAY(shadow_isect, index, t);
+#ifdef __EMBREE__
+  isect->Ng = INTEGRATOR_STATE_ARRAY(shadow_isect, index, Ng);
+#endif
+}
+
+ccl_device_forceinline void integrator_state_copy_volume_stack_to_shadow(INTEGRATOR_STATE_ARGS)
+{
+  if (kernel_data.kernel_features & KERNEL_FEATURE_VOLUME) {
+    for (int i = 0; i < INTEGRATOR_VOLUME_STACK_SIZE; i++) {
+      INTEGRATOR_STATE_ARRAY_WRITE(shadow_volume_stack, i, object) = INTEGRATOR_STATE_ARRAY(
+          volume_stack, i, object);
+      INTEGRATOR_STATE_ARRAY_WRITE(shadow_volume_stack, i, shader) = INTEGRATOR_STATE_ARRAY(
+          volume_stack, i, shader);
+    }
+  }
+}
+
+ccl_device_forceinline VolumeStack
+integrator_state_read_shadow_volume_stack(INTEGRATOR_STATE_CONST_ARGS, int i)
+{
+  VolumeStack entry = {INTEGRATOR_STATE_ARRAY(shadow_volume_stack, i, object),
+                       INTEGRATOR_STATE_ARRAY(shadow_volume_stack, i, shader)};
+  return entry;
+}
+
+ccl_device_forceinline bool integrator_state_shadow_volume_stack_is_empty(
+    INTEGRATOR_STATE_CONST_ARGS)
+{
+  return (kernel_data.kernel_features & KERNEL_FEATURE_VOLUME) ?
+             INTEGRATOR_STATE_ARRAY(shadow_volume_stack, 0, shader) == SHADER_NONE :
+             true;
+}
+
+ccl_device_forceinline void integrator_state_write_shadow_volume_stack(INTEGRATOR_STATE_ARGS,
+                                                                       int i,
+                                                                       VolumeStack entry)
+{
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_volume_stack, i, object) = entry.object;
+  INTEGRATOR_STATE_ARRAY_WRITE(shadow_volume_stack, i, shader) = entry.shader;
+}
+
+#if defined(__KERNEL_GPU__)
+ccl_device_inline void integrator_state_copy_only(const IntegratorState to_state,
+                                                  const IntegratorState state)
+{
+  int index;
+
+  /* Rely on the compiler to optimize out unused assignments and `while(false)`'s. */
+
+#  define KERNEL_STRUCT_BEGIN(name) \
+    index = 0; \
+    do {
+
+#  define KERNEL_STRUCT_MEMBER(parent_struct, type, name, feature) \
+    if (kernel_integrator_state.parent_struct.name != nullptr) { \
+      kernel_integrator_state.parent_struct.name[to_state] = \
+          kernel_integrator_state.parent_struct.name[state]; \
+    }
+
+#  define KERNEL_STRUCT_ARRAY_MEMBER(parent_struct, type, name, feature) \
+    if (kernel_integrator_state.parent_struct[index].name != nullptr) { \
+      kernel_integrator_state.parent_struct[index].name[to_state] = \
+          kernel_integrator_state.parent_struct[index].name[state]; \
+    }
+
+#  define KERNEL_STRUCT_END(name) \
+    } \
+    while (false) \
+      ;
+
+#  define KERNEL_STRUCT_END_ARRAY(name, array_size) \
+    ++index; \
+    } \
+    while (index < array_size) \
+      ;
+
+#  include "kernel/integrator/integrator_state_template.h"
+
+#  undef KERNEL_STRUCT_BEGIN
+#  undef KERNEL_STRUCT_MEMBER
+#  undef KERNEL_STRUCT_ARRAY_MEMBER
+#  undef KERNEL_STRUCT_END
+#  undef KERNEL_STRUCT_END_ARRAY
+}
+
+ccl_device_inline void integrator_state_move(const IntegratorState to_state,
+                                             const IntegratorState state)
+{
+  integrator_state_copy_only(to_state, state);
+
+  INTEGRATOR_STATE_WRITE(path, queued_kernel) = 0;
+  INTEGRATOR_STATE_WRITE(shadow_path, queued_kernel) = 0;
+}
+
+#endif
+
+/* NOTE: Leaves kernel scheduling information untouched. Use INIT semantic for one of the paths
+ * after this function. */
+ccl_device_inline void integrator_state_shadow_catcher_split(INTEGRATOR_STATE_ARGS)
+{
+#if defined(__KERNEL_GPU__)
+  const IntegratorState to_state = atomic_fetch_and_add_uint32(
+      &kernel_integrator_state.next_shadow_catcher_path_index[0], 1);
+
+  integrator_state_copy_only(to_state, state);
+
+  kernel_integrator_state.path.flag[to_state] |= PATH_RAY_SHADOW_CATCHER_PASS;
+
+  /* Sanity check: expect to split in the intersect-closest kernel, where there is no shadow ray
+   * and no sorting yet. */
+  kernel_assert(INTEGRATOR_STATE(shadow_path, queued_kernel) == 0);
+  kernel_assert(kernel_integrator_state.sort_key_counter[INTEGRATOR_STATE(path, queued_kernel)] ==
+                nullptr);
+#else
+
+  IntegratorStateCPU *ccl_restrict split_state = state + 1;
+
+  *split_state = *state;
+
+  split_state->path.flag |= PATH_RAY_SHADOW_CATCHER_PASS;
+#endif
+}
+
+CCL_NAMESPACE_END