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, 281 insertions, 0 deletions

diff --git a/intern/cycles/integrator/path_trace_work_cpu.cpp b/intern/cycles/integrator/path_trace_work_cpu.cpp
new file mode 100644
index 00000000000..b9a33b64051
--- /dev/null
+++ b/intern/cycles/integrator/path_trace_work_cpu.cpp
@@ -0,0 +1,281 @@
+/*
+ * 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.
+ */
+
+#include "integrator/path_trace_work_cpu.h"
+
+#include "device/cpu/kernel.h"
+#include "device/device.h"
+
+#include "integrator/pass_accessor_cpu.h"
+
+#include "render/buffers.h"
+#include "render/gpu_display.h"
+#include "render/scene.h"
+
+#include "util/util_atomic.h"
+#include "util/util_logging.h"
+#include "util/util_tbb.h"
+
+CCL_NAMESPACE_BEGIN
+
+/* Create TBB arena for execution of path tracing and rendering tasks. */
+static inline tbb::task_arena local_tbb_arena_create(const Device *device)
+{
+  /* TODO: limit this to number of threads of CPU device, it may be smaller than
+   * the system number of threads when we reduce the number of CPU threads in
+   * CPU + GPU rendering to dedicate some cores to handling the GPU device. */
+  return tbb::task_arena(device->info.cpu_threads);
+}
+
+/* Get CPUKernelThreadGlobals for the current thread. */
+static inline CPUKernelThreadGlobals *kernel_thread_globals_get(
+    vector<CPUKernelThreadGlobals> &kernel_thread_globals)
+{
+  const int thread_index = tbb::this_task_arena::current_thread_index();
+  DCHECK_GE(thread_index, 0);
+  DCHECK_LE(thread_index, kernel_thread_globals.size());
+
+  return &kernel_thread_globals[thread_index];
+}
+
+PathTraceWorkCPU::PathTraceWorkCPU(Device *device,
+                                   Film *film,
+                                   DeviceScene *device_scene,
+                                   bool *cancel_requested_flag)
+    : PathTraceWork(device, film, device_scene, cancel_requested_flag),
+      kernels_(*(device->get_cpu_kernels()))
+{
+  DCHECK_EQ(device->info.type, DEVICE_CPU);
+}
+
+void PathTraceWorkCPU::init_execution()
+{
+  /* Cache per-thread kernel globals. */
+  device_->get_cpu_kernel_thread_globals(kernel_thread_globals_);
+}
+
+void PathTraceWorkCPU::render_samples(RenderStatistics &statistics,
+                                      int start_sample,
+                                      int samples_num)
+{
+  const int64_t image_width = effective_buffer_params_.width;
+  const int64_t image_height = effective_buffer_params_.height;
+  const int64_t total_pixels_num = image_width * image_height;
+
+  for (CPUKernelThreadGlobals &kernel_globals : kernel_thread_globals_) {
+    kernel_globals.start_profiling();
+  }
+
+  tbb::task_arena local_arena = local_tbb_arena_create(device_);
+  local_arena.execute([&]() {
+    tbb::parallel_for(int64_t(0), total_pixels_num, [&](int64_t work_index) {
+      if (is_cancel_requested()) {
+        return;
+      }
+
+      const int y = work_index / image_width;
+      const int x = work_index - y * image_width;
+
+      KernelWorkTile work_tile;
+      work_tile.x = effective_buffer_params_.full_x + x;
+      work_tile.y = effective_buffer_params_.full_y + y;
+      work_tile.w = 1;
+      work_tile.h = 1;
+      work_tile.start_sample = start_sample;
+      work_tile.num_samples = 1;
+      work_tile.offset = effective_buffer_params_.offset;
+      work_tile.stride = effective_buffer_params_.stride;
+
+      CPUKernelThreadGlobals *kernel_globals = kernel_thread_globals_get(kernel_thread_globals_);
+
+      render_samples_full_pipeline(kernel_globals, work_tile, samples_num);
+    });
+  });
+
+  for (CPUKernelThreadGlobals &kernel_globals : kernel_thread_globals_) {
+    kernel_globals.stop_profiling();
+  }
+
+  statistics.occupancy = 1.0f;
+}
+
+void PathTraceWorkCPU::render_samples_full_pipeline(KernelGlobals *kernel_globals,
+                                                    const KernelWorkTile &work_tile,
+                                                    const int samples_num)
+{
+  const bool has_shadow_catcher = device_scene_->data.integrator.has_shadow_catcher;
+  const bool has_bake = device_scene_->data.bake.use;
+
+  IntegratorStateCPU integrator_states[2] = {};
+
+  IntegratorStateCPU *state = &integrator_states[0];
+  IntegratorStateCPU *shadow_catcher_state = &integrator_states[1];
+
+  KernelWorkTile sample_work_tile = work_tile;
+  float *render_buffer = buffers_->buffer.data();
+
+  for (int sample = 0; sample < samples_num; ++sample) {
+    if (is_cancel_requested()) {
+      break;
+    }
+
+    if (has_bake) {
+      if (!kernels_.integrator_init_from_bake(
+              kernel_globals, state, &sample_work_tile, render_buffer)) {
+        break;
+      }
+    }
+    else {
+      if (!kernels_.integrator_init_from_camera(
+              kernel_globals, state, &sample_work_tile, render_buffer)) {
+        break;
+      }
+    }
+
+    kernels_.integrator_megakernel(kernel_globals, state, render_buffer);
+
+    if (has_shadow_catcher) {
+      kernels_.integrator_megakernel(kernel_globals, shadow_catcher_state, render_buffer);
+    }
+
+    ++sample_work_tile.start_sample;
+  }
+}
+
+void PathTraceWorkCPU::copy_to_gpu_display(GPUDisplay *gpu_display,
+                                           PassMode pass_mode,
+                                           int num_samples)
+{
+  half4 *rgba_half = gpu_display->map_texture_buffer();
+  if (!rgba_half) {
+    /* TODO(sergey): Look into using copy_to_gpu_display() if mapping failed. Might be needed for
+     * some implementations of GPUDisplay which can not map memory? */
+    return;
+  }
+
+  const KernelFilm &kfilm = device_scene_->data.film;
+
+  const PassAccessor::PassAccessInfo pass_access_info = get_display_pass_access_info(pass_mode);
+
+  const PassAccessorCPU pass_accessor(pass_access_info, kfilm.exposure, num_samples);
+
+  PassAccessor::Destination destination = get_gpu_display_destination_template(gpu_display);
+  destination.pixels_half_rgba = rgba_half;
+
+  tbb::task_arena local_arena = local_tbb_arena_create(device_);
+  local_arena.execute([&]() {
+    pass_accessor.get_render_tile_pixels(buffers_.get(), effective_buffer_params_, destination);
+  });
+
+  gpu_display->unmap_texture_buffer();
+}
+
+void PathTraceWorkCPU::destroy_gpu_resources(GPUDisplay * /*gpu_display*/)
+{
+}
+
+bool PathTraceWorkCPU::copy_render_buffers_from_device()
+{
+  return buffers_->copy_from_device();
+}
+
+bool PathTraceWorkCPU::copy_render_buffers_to_device()
+{
+  buffers_->buffer.copy_to_device();
+  return true;
+}
+
+bool PathTraceWorkCPU::zero_render_buffers()
+{
+  buffers_->zero();
+  return true;
+}
+
+int PathTraceWorkCPU::adaptive_sampling_converge_filter_count_active(float threshold, bool reset)
+{
+  const int full_x = effective_buffer_params_.full_x;
+  const int full_y = effective_buffer_params_.full_y;
+  const int width = effective_buffer_params_.width;
+  const int height = effective_buffer_params_.height;
+  const int offset = effective_buffer_params_.offset;
+  const int stride = effective_buffer_params_.stride;
+
+  float *render_buffer = buffers_->buffer.data();
+
+  uint num_active_pixels = 0;
+
+  tbb::task_arena local_arena = local_tbb_arena_create(device_);
+
+  /* Check convergency and do x-filter in a single `parallel_for`, to reduce threading overhead. */
+  local_arena.execute([&]() {
+    tbb::parallel_for(full_y, full_y + height, [&](int y) {
+      CPUKernelThreadGlobals *kernel_globals = &kernel_thread_globals_[0];
+
+      bool row_converged = true;
+      uint num_row_pixels_active = 0;
+      for (int x = 0; x < width; ++x) {
+        if (!kernels_.adaptive_sampling_convergence_check(
+                kernel_globals, render_buffer, full_x + x, y, threshold, reset, offset, stride)) {
+          ++num_row_pixels_active;
+          row_converged = false;
+        }
+      }
+
+      atomic_fetch_and_add_uint32(&num_active_pixels, num_row_pixels_active);
+
+      if (!row_converged) {
+        kernels_.adaptive_sampling_filter_x(
+            kernel_globals, render_buffer, y, full_x, width, offset, stride);
+      }
+    });
+  });
+
+  if (num_active_pixels) {
+    local_arena.execute([&]() {
+      tbb::parallel_for(full_x, full_x + width, [&](int x) {
+        CPUKernelThreadGlobals *kernel_globals = &kernel_thread_globals_[0];
+        kernels_.adaptive_sampling_filter_y(
+            kernel_globals, render_buffer, x, full_y, height, offset, stride);
+      });
+    });
+  }
+
+  return num_active_pixels;
+}
+
+void PathTraceWorkCPU::cryptomatte_postproces()
+{
+  const int width = effective_buffer_params_.width;
+  const int height = effective_buffer_params_.height;
+
+  float *render_buffer = buffers_->buffer.data();
+
+  tbb::task_arena local_arena = local_tbb_arena_create(device_);
+
+  /* Check convergency and do x-filter in a single `parallel_for`, to reduce threading overhead. */
+  local_arena.execute([&]() {
+    tbb::parallel_for(0, height, [&](int y) {
+      CPUKernelThreadGlobals *kernel_globals = &kernel_thread_globals_[0];
+      int pixel_index = y * width;
+
+      for (int x = 0; x < width; ++x, ++pixel_index) {
+        kernels_.cryptomatte_postprocess(kernel_globals, render_buffer, pixel_index);
+      }
+    });
+  });
+}
+
+CCL_NAMESPACE_END