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, 163 insertions, 0 deletions

diff --git a/intern/cycles/kernel/integrator/integrator_state_template.h b/intern/cycles/kernel/integrator/integrator_state_template.h
new file mode 100644
index 00000000000..41dd1bfcdbf
--- /dev/null
+++ b/intern/cycles/kernel/integrator/integrator_state_template.h
@@ -0,0 +1,163 @@
+
+/*
+ * 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.
+ */
+
+/************************************ Path State *****************************/
+
+KERNEL_STRUCT_BEGIN(path)
+/* Index of a pixel within the device render buffer where this path will write its result.
+ * To get an actual offset within the buffer the value needs to be multiplied by the
+ * `kernel_data.film.pass_stride`.
+ *
+ * The multiplication is delayed for later, so that state can use 32bit integer. */
+KERNEL_STRUCT_MEMBER(path, uint32_t, render_pixel_index, KERNEL_FEATURE_PATH_TRACING)
+/* Current sample number. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, sample, KERNEL_FEATURE_PATH_TRACING)
+/* Current ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current diffuse ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, diffuse_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current glossy ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, glossy_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current transmission ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, transmission_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current volume ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, volume_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current volume bounds ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, volume_bounds_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current transparent ray bounce depth. */
+KERNEL_STRUCT_MEMBER(path, uint16_t, transparent_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* DeviceKernel bit indicating queued kernels.
+ * TODO: reduce size? */
+KERNEL_STRUCT_MEMBER(path, uint32_t, queued_kernel, KERNEL_FEATURE_PATH_TRACING)
+/* Random number generator seed. */
+KERNEL_STRUCT_MEMBER(path, uint32_t, rng_hash, KERNEL_FEATURE_PATH_TRACING)
+/* Random number dimension offset. */
+KERNEL_STRUCT_MEMBER(path, uint32_t, rng_offset, KERNEL_FEATURE_PATH_TRACING)
+/* enum PathRayFlag */
+KERNEL_STRUCT_MEMBER(path, uint32_t, flag, KERNEL_FEATURE_PATH_TRACING)
+/* Multiple importance sampling
+ * The PDF of BSDF sampling at the last scatter point, and distance to the
+ * last scatter point minus the last ray segment. This distance lets us
+ * compute the complete distance through transparent surfaces and volumes. */
+KERNEL_STRUCT_MEMBER(path, float, mis_ray_pdf, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(path, float, mis_ray_t, KERNEL_FEATURE_PATH_TRACING)
+/* Filter glossy. */
+KERNEL_STRUCT_MEMBER(path, float, min_ray_pdf, KERNEL_FEATURE_PATH_TRACING)
+/* Throughput. */
+KERNEL_STRUCT_MEMBER(path, float3, throughput, KERNEL_FEATURE_PATH_TRACING)
+/* Ratio of throughput to distinguish diffuse and glossy render passes. */
+KERNEL_STRUCT_MEMBER(path, float3, diffuse_glossy_ratio, KERNEL_FEATURE_LIGHT_PASSES)
+/* Denoising. */
+KERNEL_STRUCT_MEMBER(path, float3, denoising_feature_throughput, KERNEL_FEATURE_DENOISING)
+/* Shader sorting. */
+/* TODO: compress as uint16? or leave out entirely and recompute key in sorting code? */
+KERNEL_STRUCT_MEMBER(path, uint32_t, shader_sort_key, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END(path)
+
+/************************************** Ray ***********************************/
+
+KERNEL_STRUCT_BEGIN(ray)
+KERNEL_STRUCT_MEMBER(ray, float3, P, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(ray, float3, D, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(ray, float, t, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(ray, float, time, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(ray, float, dP, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(ray, float, dD, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END(ray)
+
+/*************************** Intersection result ******************************/
+
+/* Result from scene intersection. */
+KERNEL_STRUCT_BEGIN(isect)
+KERNEL_STRUCT_MEMBER(isect, float, t, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(isect, float, u, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(isect, float, v, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(isect, int, prim, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(isect, int, object, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(isect, int, type, KERNEL_FEATURE_PATH_TRACING)
+/* TODO: exclude for GPU. */
+KERNEL_STRUCT_MEMBER(isect, float3, Ng, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END(isect)
+
+/*************** Subsurface closure state for subsurface kernel ***************/
+
+KERNEL_STRUCT_BEGIN(subsurface)
+KERNEL_STRUCT_MEMBER(subsurface, float3, albedo, KERNEL_FEATURE_SUBSURFACE)
+KERNEL_STRUCT_MEMBER(subsurface, float3, radius, KERNEL_FEATURE_SUBSURFACE)
+KERNEL_STRUCT_MEMBER(subsurface, float, anisotropy, KERNEL_FEATURE_SUBSURFACE)
+KERNEL_STRUCT_MEMBER(subsurface, float, roughness, KERNEL_FEATURE_SUBSURFACE)
+KERNEL_STRUCT_END(subsurface)
+
+/********************************** Volume Stack ******************************/
+
+KERNEL_STRUCT_BEGIN(volume_stack)
+KERNEL_STRUCT_ARRAY_MEMBER(volume_stack, int, object, KERNEL_FEATURE_VOLUME)
+KERNEL_STRUCT_ARRAY_MEMBER(volume_stack, int, shader, KERNEL_FEATURE_VOLUME)
+KERNEL_STRUCT_END_ARRAY(volume_stack, INTEGRATOR_VOLUME_STACK_SIZE)
+
+/********************************* Shadow Path State **************************/
+
+KERNEL_STRUCT_BEGIN(shadow_path)
+/* Current ray bounce depth. */
+KERNEL_STRUCT_MEMBER(shadow_path, uint16_t, bounce, KERNEL_FEATURE_PATH_TRACING)
+/* Current transparent ray bounce depth. */
+KERNEL_STRUCT_MEMBER(shadow_path, uint16_t, transparent_bounce, KERNEL_FEATURE_PATH_TRACING)
+/* DeviceKernel bit indicating queued kernels.
+ * TODO: reduce size? */
+KERNEL_STRUCT_MEMBER(shadow_path, uint32_t, queued_kernel, KERNEL_FEATURE_PATH_TRACING)
+/* enum PathRayFlag */
+KERNEL_STRUCT_MEMBER(shadow_path, uint32_t, flag, KERNEL_FEATURE_PATH_TRACING)
+/* Throughput. */
+KERNEL_STRUCT_MEMBER(shadow_path, float3, throughput, KERNEL_FEATURE_PATH_TRACING)
+/* Throughput for shadow pass. */
+KERNEL_STRUCT_MEMBER(shadow_path, float3, unshadowed_throughput, KERNEL_FEATURE_SHADOW_PASS)
+/* Ratio of throughput to distinguish diffuse and glossy render passes. */
+KERNEL_STRUCT_MEMBER(shadow_path, float3, diffuse_glossy_ratio, KERNEL_FEATURE_LIGHT_PASSES)
+/* Number of intersections found by ray-tracing. */
+KERNEL_STRUCT_MEMBER(shadow_path, uint16_t, num_hits, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END(shadow_path)
+
+/********************************** Shadow Ray *******************************/
+
+KERNEL_STRUCT_BEGIN(shadow_ray)
+KERNEL_STRUCT_MEMBER(shadow_ray, float3, P, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(shadow_ray, float3, D, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(shadow_ray, float, t, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(shadow_ray, float, time, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_MEMBER(shadow_ray, float, dP, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END(shadow_ray)
+
+/*********************** Shadow Intersection result **************************/
+
+/* Result from scene intersection. */
+KERNEL_STRUCT_BEGIN(shadow_isect)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, float, t, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, float, u, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, float, v, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, int, prim, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, int, object, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, int, type, KERNEL_FEATURE_PATH_TRACING)
+/* TODO: exclude for GPU. */
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_isect, float3, Ng, KERNEL_FEATURE_PATH_TRACING)
+KERNEL_STRUCT_END_ARRAY(shadow_isect, INTEGRATOR_SHADOW_ISECT_SIZE)
+
+/**************************** Shadow Volume Stack *****************************/
+
+KERNEL_STRUCT_BEGIN(shadow_volume_stack)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_volume_stack, int, object, KERNEL_FEATURE_VOLUME)
+KERNEL_STRUCT_ARRAY_MEMBER(shadow_volume_stack, int, shader, KERNEL_FEATURE_VOLUME)
+KERNEL_STRUCT_END_ARRAY(shadow_volume_stack, INTEGRATOR_VOLUME_STACK_SIZE)