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, 82 insertions, 0 deletions

diff --git a/intern/cycles/integrator/path_trace_work_cpu.h b/intern/cycles/integrator/path_trace_work_cpu.h
new file mode 100644
index 00000000000..ab729bbf879
--- /dev/null
+++ b/intern/cycles/integrator/path_trace_work_cpu.h
@@ -0,0 +1,82 @@
+/*
+ * 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 "device/cpu/kernel_thread_globals.h"
+#include "device/device_queue.h"
+
+#include "integrator/path_trace_work.h"
+
+#include "util/util_vector.h"
+
+CCL_NAMESPACE_BEGIN
+
+struct KernelWorkTile;
+struct KernelGlobals;
+
+class CPUKernels;
+
+/* Implementation of PathTraceWork which schedules work on to queues pixel-by-pixel,
+ * for CPU devices.
+ *
+ * NOTE: For the CPU rendering there are assumptions about TBB arena size and number of concurrent
+ * queues on the render device which makes this work be only usable on CPU. */
+class PathTraceWorkCPU : public PathTraceWork {
+ public:
+  PathTraceWorkCPU(Device *device,
+                   Film *film,
+                   DeviceScene *device_scene,
+                   bool *cancel_requested_flag);
+
+  virtual void init_execution() override;
+
+  virtual void render_samples(RenderStatistics &statistics,
+                              int start_sample,
+                              int samples_num) override;
+
+  virtual void copy_to_gpu_display(GPUDisplay *gpu_display,
+                                   PassMode pass_mode,
+                                   int num_samples) override;
+  virtual void destroy_gpu_resources(GPUDisplay *gpu_display) override;
+
+  virtual bool copy_render_buffers_from_device() override;
+  virtual bool copy_render_buffers_to_device() override;
+  virtual bool zero_render_buffers() override;
+
+  virtual int adaptive_sampling_converge_filter_count_active(float threshold, bool reset) override;
+  virtual void cryptomatte_postproces() override;
+
+ protected:
+  /* Core path tracing routine. Renders given work time on the given queue. */
+  void render_samples_full_pipeline(KernelGlobals *kernel_globals,
+                                    const KernelWorkTile &work_tile,
+                                    const int samples_num);
+
+  /* CPU kernels. */
+  const CPUKernels &kernels_;
+
+  /* Copy of kernel globals which is suitable for concurrent access from multiple threads.
+   *
+   * More specifically, the `kernel_globals_` is local to each threads and nobody else is
+   * accessing it, but some "localization" is required to decouple from kernel globals stored
+   * on the device level. */
+  vector<CPUKernelThreadGlobals> kernel_thread_globals_;
+};
+
+CCL_NAMESPACE_END