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, 185 insertions, 0 deletions

diff --git a/intern/cycles/kernel/integrator/integrator_state.h b/intern/cycles/kernel/integrator/integrator_state.h
new file mode 100644
index 00000000000..8cef9cf31e2
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_state.h
@@ -0,0 +1,185 @@
+/*
+ * 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.
+ */
+
+/* Integrator State
+ *
+ * This file defines the data structures that define the state of a path. Any state that is
+ * preserved and passed between kernel executions is part of this.
+ *
+ * The size of this state must be kept as small as possible, to reduce cache misses and keep memory
+ * usage under control on GPUs that may execute millions of kernels.
+ *
+ * Memory may be allocated and passed along in different ways depending on the device. There may
+ * be a scalar layout, or AoS or SoA layout for batches. The state may be passed along as a pointer
+ * to every kernel, or the pointer may exist at program scope or in constant memory. To abstract
+ * these differences between devices and experiment with different layouts, macros are used.
+ *
+ * INTEGRATOR_STATE_ARGS: prepend to argument definitions for every function that accesses
+ * path state.
+ * INTEGRATOR_STATE_CONST_ARGS: same as INTEGRATOR_STATE_ARGS, when state is read-only
+ * INTEGRATOR_STATE_PASS: use to pass along state to other functions access it.
+ *
+ * INTEGRATOR_STATE(x, y): read nested struct member x.y of IntegratorState
+ * INTEGRATOR_STATE_WRITE(x, y): write to nested struct member x.y of IntegratorState
+ *
+ * INTEGRATOR_STATE_ARRAY(x, index, y): read x[index].y
+ * INTEGRATOR_STATE_ARRAY_WRITE(x, index, y): write x[index].y
+ *
+ * INTEGRATOR_STATE_COPY(to_x, from_x): copy contents of one nested struct to another
+ *
+ * INTEGRATOR_STATE_IS_NULL: test if any integrator state is available, for shader evaluation
+ * INTEGRATOR_STATE_PASS_NULL: use to pass empty state to other functions.
+ *
+ * NOTE: if we end up with a device that passes no arguments, the leading comma will be a problem.
+ * Can solve it with more macros if we encouter it, but rather ugly so postpone for now.
+ */
+
+#include "kernel/kernel_types.h"
+
+#include "util/util_types.h"
+
+#pragma once
+
+CCL_NAMESPACE_BEGIN
+
+/* Constants
+ *
+ * TODO: these could be made dynamic depending on the features used in the scene. */
+
+#define INTEGRATOR_VOLUME_STACK_SIZE VOLUME_STACK_SIZE
+#define INTEGRATOR_SHADOW_ISECT_SIZE 4
+
+/* Data structures */
+
+/* Integrator State
+ *
+ * CPU rendering path state with AoS layout. */
+typedef struct IntegratorStateCPU {
+#define KERNEL_STRUCT_BEGIN(name) struct {
+#define KERNEL_STRUCT_MEMBER(parent_struct, type, name, feature) type name;
+#define KERNEL_STRUCT_ARRAY_MEMBER KERNEL_STRUCT_MEMBER
+#define KERNEL_STRUCT_END(name) \
+  } \
+  name;
+#define KERNEL_STRUCT_END_ARRAY(name, size) \
+  } \
+  name[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
+} IntegratorStateCPU;
+
+/* Path Queue
+ *
+ * Keep track of which kernels are queued to be executed next in the path
+ * for GPU rendering. */
+typedef struct IntegratorQueueCounter {
+  int num_queued[DEVICE_KERNEL_INTEGRATOR_NUM];
+} IntegratorQueueCounter;
+
+/* Integrator State GPU
+ *
+ * GPU rendering path state with SoA layout. */
+typedef struct IntegratorStateGPU {
+#define KERNEL_STRUCT_BEGIN(name) struct {
+#define KERNEL_STRUCT_MEMBER(parent_struct, type, name, feature) type *name;
+#define KERNEL_STRUCT_ARRAY_MEMBER KERNEL_STRUCT_MEMBER
+#define KERNEL_STRUCT_END(name) \
+  } \
+  name;
+#define KERNEL_STRUCT_END_ARRAY(name, size) \
+  } \
+  name[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
+
+  /* Count number of queued kernels. */
+  IntegratorQueueCounter *queue_counter;
+
+  /* Count number of kernels queued for specific shaders. */
+  int *sort_key_counter[DEVICE_KERNEL_INTEGRATOR_NUM];
+
+  /* Index of path which will be used by a next shadow catcher split.  */
+  int *next_shadow_catcher_path_index;
+} IntegratorStateGPU;
+
+/* Abstraction
+ *
+ * Macros to access data structures on different devices.
+ *
+ * Note that there is a special access function for the shadow catcher state. This access is to
+ * happen from a kernel which operates on a "main" path. Attempt to use shadow catcher accessors
+ * from a kernel which operates on a shadow catcher state will cause bad memory acces. */
+
+#ifdef __KERNEL_CPU__
+
+/* Scalar access on CPU. */
+
+typedef IntegratorStateCPU *ccl_restrict IntegratorState;
+
+#  define INTEGRATOR_STATE_ARGS \
+    ccl_attr_maybe_unused const KernelGlobals *ccl_restrict kg, \
+        IntegratorStateCPU *ccl_restrict state
+#  define INTEGRATOR_STATE_CONST_ARGS \
+    ccl_attr_maybe_unused const KernelGlobals *ccl_restrict kg, \
+        const IntegratorStateCPU *ccl_restrict state
+#  define INTEGRATOR_STATE_PASS kg, state
+
+#  define INTEGRATOR_STATE_PASS_NULL kg, NULL
+#  define INTEGRATOR_STATE_IS_NULL (state == NULL)
+
+#  define INTEGRATOR_STATE(nested_struct, member) \
+    (((const IntegratorStateCPU *)state)->nested_struct.member)
+#  define INTEGRATOR_STATE_WRITE(nested_struct, member) (state->nested_struct.member)
+
+#  define INTEGRATOR_STATE_ARRAY(nested_struct, array_index, member) \
+    (((const IntegratorStateCPU *)state)->nested_struct[array_index].member)
+#  define INTEGRATOR_STATE_ARRAY_WRITE(nested_struct, array_index, member) \
+    ((state)->nested_struct[array_index].member)
+
+#else /* __KERNEL_CPU__ */
+
+/* Array access on GPU with Structure-of-Arrays. */
+
+typedef int IntegratorState;
+
+#  define INTEGRATOR_STATE_ARGS const KernelGlobals *ccl_restrict kg, const IntegratorState state
+#  define INTEGRATOR_STATE_CONST_ARGS \
+    const KernelGlobals *ccl_restrict kg, const IntegratorState state
+#  define INTEGRATOR_STATE_PASS kg, state
+
+#  define INTEGRATOR_STATE_PASS_NULL kg, -1
+#  define INTEGRATOR_STATE_IS_NULL (state == -1)
+
+#  define INTEGRATOR_STATE(nested_struct, member) \
+    kernel_integrator_state.nested_struct.member[state]
+#  define INTEGRATOR_STATE_WRITE(nested_struct, member) INTEGRATOR_STATE(nested_struct, member)
+
+#  define INTEGRATOR_STATE_ARRAY(nested_struct, array_index, member) \
+    kernel_integrator_state.nested_struct[array_index].member[state]
+#  define INTEGRATOR_STATE_ARRAY_WRITE(nested_struct, array_index, member) \
+    INTEGRATOR_STATE_ARRAY(nested_struct, array_index, member)
+
+#endif /* __KERNEL_CPU__ */
+
+CCL_NAMESPACE_END