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, 93 insertions, 0 deletions

diff --git a/intern/cycles/kernel/integrator/integrator_megakernel.h b/intern/cycles/kernel/integrator/integrator_megakernel.h
new file mode 100644
index 00000000000..91363ea1c7f
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_megakernel.h
@@ -0,0 +1,93 @@
+/*
+ * 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_init_from_camera.h"
+#include "kernel/integrator/integrator_intersect_closest.h"
+#include "kernel/integrator/integrator_intersect_shadow.h"
+#include "kernel/integrator/integrator_intersect_subsurface.h"
+#include "kernel/integrator/integrator_intersect_volume_stack.h"
+#include "kernel/integrator/integrator_shade_background.h"
+#include "kernel/integrator/integrator_shade_light.h"
+#include "kernel/integrator/integrator_shade_shadow.h"
+#include "kernel/integrator/integrator_shade_surface.h"
+#include "kernel/integrator/integrator_shade_volume.h"
+
+CCL_NAMESPACE_BEGIN
+
+ccl_device void integrator_megakernel(INTEGRATOR_STATE_ARGS,
+                                      ccl_global float *ccl_restrict render_buffer)
+{
+  /* Each kernel indicates the next kernel to execute, so here we simply
+   * have to check what that kernel is and execute it.
+   *
+   * TODO: investigate if we can use device side enqueue for GPUs to avoid
+   * having to compile this big kernel. */
+  while (true) {
+    if (INTEGRATOR_STATE(shadow_path, queued_kernel)) {
+      /* First handle any shadow paths before we potentially create more shadow paths. */
+      switch (INTEGRATOR_STATE(shadow_path, queued_kernel)) {
+        case DEVICE_KERNEL_INTEGRATOR_INTERSECT_SHADOW:
+          integrator_intersect_shadow(INTEGRATOR_STATE_PASS);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_SHADOW:
+          integrator_shade_shadow(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        default:
+          kernel_assert(0);
+          break;
+      }
+    }
+    else if (INTEGRATOR_STATE(path, queued_kernel)) {
+      /* Then handle regular path kernels. */
+      switch (INTEGRATOR_STATE(path, queued_kernel)) {
+        case DEVICE_KERNEL_INTEGRATOR_INTERSECT_CLOSEST:
+          integrator_intersect_closest(INTEGRATOR_STATE_PASS);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_BACKGROUND:
+          integrator_shade_background(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_SURFACE:
+          integrator_shade_surface(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_VOLUME:
+          integrator_shade_volume(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_SURFACE_RAYTRACE:
+          integrator_shade_surface_raytrace(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT:
+          integrator_shade_light(INTEGRATOR_STATE_PASS, render_buffer);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_INTERSECT_SUBSURFACE:
+          integrator_intersect_subsurface(INTEGRATOR_STATE_PASS);
+          break;
+        case DEVICE_KERNEL_INTEGRATOR_INTERSECT_VOLUME_STACK:
+          integrator_intersect_volume_stack(INTEGRATOR_STATE_PASS);
+          break;
+        default:
+          kernel_assert(0);
+          break;
+      }
+    }
+    else {
+      break;
+    }
+  }
+}
+
+CCL_NAMESPACE_END