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, 120 insertions, 0 deletions

diff --git a/intern/cycles/kernel/integrator/integrator_init_from_camera.h b/intern/cycles/kernel/integrator/integrator_init_from_camera.h
new file mode 100644
index 00000000000..58e7bde4c94
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_init_from_camera.h
@@ -0,0 +1,120 @@
+/*
+ * 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/kernel_accumulate.h"
+#include "kernel/kernel_adaptive_sampling.h"
+#include "kernel/kernel_camera.h"
+#include "kernel/kernel_path_state.h"
+#include "kernel/kernel_random.h"
+#include "kernel/kernel_shadow_catcher.h"
+
+CCL_NAMESPACE_BEGIN
+
+ccl_device_inline void integrate_camera_sample(const KernelGlobals *ccl_restrict kg,
+                                               const int sample,
+                                               const int x,
+                                               const int y,
+                                               const uint rng_hash,
+                                               Ray *ray)
+{
+  /* Filter sampling. */
+  float filter_u, filter_v;
+
+  if (sample == 0) {
+    filter_u = 0.5f;
+    filter_v = 0.5f;
+  }
+  else {
+    path_rng_2D(kg, rng_hash, sample, PRNG_FILTER_U, &filter_u, &filter_v);
+  }
+
+  /* Depth of field sampling. */
+  float lens_u = 0.0f, lens_v = 0.0f;
+  if (kernel_data.cam.aperturesize > 0.0f) {
+    path_rng_2D(kg, rng_hash, sample, PRNG_LENS_U, &lens_u, &lens_v);
+  }
+
+  /* Motion blur time sampling. */
+  float time = 0.0f;
+#ifdef __CAMERA_MOTION__
+  if (kernel_data.cam.shuttertime != -1.0f)
+    time = path_rng_1D(kg, rng_hash, sample, PRNG_TIME);
+#endif
+
+  /* Generate camera ray. */
+  camera_sample(kg, x, y, filter_u, filter_v, lens_u, lens_v, time, ray);
+}
+
+/* Return false to indicate that this pixel is finished.
+ * Used by CPU implementation to not attempt to sample pixel for multiple samples once its known
+ * that the pixel did converge. */
+ccl_device bool integrator_init_from_camera(INTEGRATOR_STATE_ARGS,
+                                            const ccl_global KernelWorkTile *ccl_restrict tile,
+                                            ccl_global float *render_buffer,
+                                            const int x,
+                                            const int y,
+                                            const int scheduled_sample)
+{
+  PROFILING_INIT(kg, PROFILING_RAY_SETUP);
+
+  /* Initialize path state to give basic buffer access and allow early outputs. */
+  path_state_init(INTEGRATOR_STATE_PASS, tile, x, y);
+
+  /* Check whether the pixel has converged and should not be sampled anymore. */
+  if (!kernel_need_sample_pixel(INTEGRATOR_STATE_PASS, render_buffer)) {
+    return false;
+  }
+
+  /* Count the sample and get an effective sample for this pixel.
+   *
+   * This logic allows to both count actual number of samples per pixel, and to add samples to this
+   * pixel after it was converged and samples were added somewhere else (in which case the
+   * `scheduled_sample` will be different from actual number of samples in this pixel). */
+  const int sample = kernel_accum_sample(INTEGRATOR_STATE_PASS, render_buffer, scheduled_sample);
+
+  /* Initialize random number seed for path. */
+  const uint rng_hash = path_rng_hash_init(kg, sample, x, y);
+
+  {
+    /* Generate camera ray. */
+    Ray ray;
+    integrate_camera_sample(kg, sample, x, y, rng_hash, &ray);
+    if (ray.t == 0.0f) {
+      return true;
+    }
+
+    /* Write camera ray to state. */
+    integrator_state_write_ray(INTEGRATOR_STATE_PASS, &ray);
+  }
+
+  /* Initialize path state for path integration. */
+  path_state_init_integrator(INTEGRATOR_STATE_PASS, sample, rng_hash);
+
+  /* Continue with intersect_closest kernel, optionally initializing volume
+   * stack before that if the camera may be inside a volume. */
+  if (kernel_data.cam.is_inside_volume) {
+    INTEGRATOR_PATH_INIT(DEVICE_KERNEL_INTEGRATOR_INTERSECT_VOLUME_STACK);
+  }
+  else {
+    INTEGRATOR_PATH_INIT(DEVICE_KERNEL_INTEGRATOR_INTERSECT_CLOSEST);
+  }
+
+  return true;
+}
+
+CCL_NAMESPACE_END