d7aee5a580
Previously, the Principled BSDF used the Subsurface input to scale the radius. When it was zero, it used a diffuse closure, otherwise a subsurface closure. This sort of scaling input makes sense, but it should be specified in distance units, rather than a 0..1 factor, so this commit changes the unit and renames the input to Subsurface Scale. Additionally, it adds support for mixing diffuse and subsurface components. This is part of e.g. the OpenPBR spec, and the logic behind it is to support modeling e.g. dirt or paint on top of skin. Before, materials would be either fully diffuse (radius=0) or fully subsurface. For typical materials, this mixing factor will be either zero or one (just like metallic or transmission), but supporting fractional inputs makes sense for e.g. smooth transitions at boundaries. Another change is that there is no separate Subsurface Color anymore - before, this was mixed with the Base Color using the Subsurface input as the factor, but this was not really useful since that input was generally very small. And finally, the handling of how the path enters the material for random walk subsurface scattering is changed. Before, this always used lambertian (diffuse) transmission, but this caused some problems, like overly white edges. Instead, two different methods are now used, depending on the selected mode. In Fixed Radius mode, the code assumes a simple medium boundary, and performs refraction into the material using the main Roughness and IOR inputs. Meanwhile, when not using Fixed Radius, the code assumes a more complex boundary (as typically found on organic materials, e.g. skin), so the entry bounce has a 50/50 chance of being either diffuse transmission or refraction using the separate Subsurface IOR input and a fixed roughness of 1. Credit for this method goes to Christophe Hery. Pull Request: https://projects.blender.org/blender/blender/pulls/110989
148 lines
8.0 KiB
C
148 lines
8.0 KiB
C
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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/************************************ Path State *****************************/
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KERNEL_STRUCT_BEGIN(path)
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/* Index of a pixel within the device render buffer where this path will write its result.
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* To get an actual offset within the buffer the value needs to be multiplied by the
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* `kernel_data.film.pass_stride`.
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*
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* The multiplication is delayed for later, so that state can use 32bit integer. */
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KERNEL_STRUCT_MEMBER(path, uint32_t, render_pixel_index, KERNEL_FEATURE_PATH_TRACING)
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/* Current sample number. */
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KERNEL_STRUCT_MEMBER(path, uint32_t, sample, KERNEL_FEATURE_PATH_TRACING)
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/* Current ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current transparent ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, transparent_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current diffuse ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, diffuse_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current glossy ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, glossy_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current transmission ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, transmission_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current volume ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, volume_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* Current volume bounds ray bounce depth. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, volume_bounds_bounce, KERNEL_FEATURE_PATH_TRACING)
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/* DeviceKernel bit indicating queued kernels. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, queued_kernel, KERNEL_FEATURE_PATH_TRACING)
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/* Random number generator seed. */
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KERNEL_STRUCT_MEMBER(path, uint32_t, rng_hash, KERNEL_FEATURE_PATH_TRACING)
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/* Random number dimension offset. */
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KERNEL_STRUCT_MEMBER(path, uint16_t, rng_offset, KERNEL_FEATURE_PATH_TRACING)
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/* enum PathRayFlag */
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KERNEL_STRUCT_MEMBER(path, uint32_t, flag, KERNEL_FEATURE_PATH_TRACING)
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/* enum PathRayMNEE */
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KERNEL_STRUCT_MEMBER(path, uint8_t, mnee, KERNEL_FEATURE_PATH_TRACING)
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/* Multiple importance sampling
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* The PDF of BSDF sampling at the last scatter point, which is at ray distance
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* zero and distance. Note that transparency and volume attenuation increase
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* the ray tmin but keep P unmodified so that this works. */
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KERNEL_STRUCT_MEMBER(path, float, mis_ray_pdf, KERNEL_FEATURE_PATH_TRACING)
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/* Object at last scatter point for light linking. */
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KERNEL_STRUCT_MEMBER(path, int, mis_ray_object, KERNEL_FEATURE_LIGHT_LINKING)
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/* Normal at last scatter point for light tree. */
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KERNEL_STRUCT_MEMBER(path, packed_float3, mis_origin_n, KERNEL_FEATURE_PATH_TRACING)
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/* Filter glossy. */
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KERNEL_STRUCT_MEMBER(path, float, min_ray_pdf, KERNEL_FEATURE_PATH_TRACING)
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/* Continuation probability for path termination. */
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KERNEL_STRUCT_MEMBER(path, float, continuation_probability, KERNEL_FEATURE_PATH_TRACING)
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/* Throughput. */
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KERNEL_STRUCT_MEMBER(path, PackedSpectrum, throughput, KERNEL_FEATURE_PATH_TRACING)
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/* Factor to multiple with throughput to get remove any guiding PDFS.
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* Such throughput without guiding PDFS is used for Russian roulette termination. */
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KERNEL_STRUCT_MEMBER(path, float, unguided_throughput, KERNEL_FEATURE_PATH_GUIDING)
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/* Ratio of throughput to distinguish diffuse / glossy / transmission render passes. */
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KERNEL_STRUCT_MEMBER(path, PackedSpectrum, pass_diffuse_weight, KERNEL_FEATURE_LIGHT_PASSES)
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KERNEL_STRUCT_MEMBER(path, PackedSpectrum, pass_glossy_weight, KERNEL_FEATURE_LIGHT_PASSES)
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/* Denoising. */
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KERNEL_STRUCT_MEMBER(path, PackedSpectrum, denoising_feature_throughput, KERNEL_FEATURE_DENOISING)
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/* Shader sorting. */
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/* TODO: compress as uint16? or leave out entirely and recompute key in sorting code? */
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KERNEL_STRUCT_MEMBER(path, uint32_t, shader_sort_key, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_END(path)
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/************************************** Ray ***********************************/
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KERNEL_STRUCT_BEGIN(ray)
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KERNEL_STRUCT_MEMBER(ray, packed_float3, P, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, packed_float3, D, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, float, tmin, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, float, tmax, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, float, time, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, float, dP, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(ray, float, dD, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_END(ray)
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/*************************** Intersection result ******************************/
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/* Result from scene intersection. */
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KERNEL_STRUCT_BEGIN(isect)
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KERNEL_STRUCT_MEMBER(isect, float, t, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(isect, float, u, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(isect, float, v, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(isect, int, prim, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(isect, int, object, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_MEMBER(isect, int, type, KERNEL_FEATURE_PATH_TRACING)
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KERNEL_STRUCT_END(isect)
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/*************** Subsurface closure state for subsurface kernel ***************/
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KERNEL_STRUCT_BEGIN(subsurface)
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KERNEL_STRUCT_MEMBER(subsurface, PackedSpectrum, albedo, KERNEL_FEATURE_SUBSURFACE)
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KERNEL_STRUCT_MEMBER(subsurface, PackedSpectrum, radius, KERNEL_FEATURE_SUBSURFACE)
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KERNEL_STRUCT_MEMBER(subsurface, float, anisotropy, KERNEL_FEATURE_SUBSURFACE)
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KERNEL_STRUCT_MEMBER(subsurface, packed_float3, N, KERNEL_FEATURE_SUBSURFACE)
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KERNEL_STRUCT_END(subsurface)
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/********************************** Volume Stack ******************************/
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KERNEL_STRUCT_BEGIN(volume_stack)
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KERNEL_STRUCT_ARRAY_MEMBER(volume_stack, int, object, KERNEL_FEATURE_VOLUME)
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KERNEL_STRUCT_ARRAY_MEMBER(volume_stack, int, shader, KERNEL_FEATURE_VOLUME)
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KERNEL_STRUCT_END_ARRAY(volume_stack,
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KERNEL_STRUCT_VOLUME_STACK_SIZE,
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KERNEL_STRUCT_VOLUME_STACK_SIZE)
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/************************************ Path Guiding *****************************/
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KERNEL_STRUCT_BEGIN(guiding)
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#ifdef __PATH_GUIDING__
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/* Current path segment of the random walk/path. */
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KERNEL_STRUCT_MEMBER(guiding,
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openpgl::cpp::PathSegment *,
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path_segment,
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KERNEL_FEATURE_PATH_GUIDING)
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#else
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/* Current path segment of the random walk/path. */
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KERNEL_STRUCT_MEMBER(guiding, uint64_t, path_segment, KERNEL_FEATURE_PATH_GUIDING)
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#endif
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/* If surface guiding is enabled */
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KERNEL_STRUCT_MEMBER(guiding, bool, use_surface_guiding, KERNEL_FEATURE_PATH_GUIDING)
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/* Random number used for additional guiding decisions (e.g., cache query, selection to use guiding
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* or BSDF sampling) */
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KERNEL_STRUCT_MEMBER(guiding, float, sample_surface_guiding_rand, KERNEL_FEATURE_PATH_GUIDING)
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/* The probability to use surface guiding (i.e., diffuse sampling prob * guiding prob)*/
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KERNEL_STRUCT_MEMBER(guiding, float, surface_guiding_sampling_prob, KERNEL_FEATURE_PATH_GUIDING)
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/* Probability of sampling a BSSRDF closure instead of a BSDF closure. */
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KERNEL_STRUCT_MEMBER(guiding, float, bssrdf_sampling_prob, KERNEL_FEATURE_PATH_GUIDING)
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/* If volume guiding is enabled */
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KERNEL_STRUCT_MEMBER(guiding, bool, use_volume_guiding, KERNEL_FEATURE_PATH_GUIDING)
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/* Random number used for additional guiding decisions (e.g., cache query, selection to use guiding
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* or BSDF sampling) */
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KERNEL_STRUCT_MEMBER(guiding, float, sample_volume_guiding_rand, KERNEL_FEATURE_PATH_GUIDING)
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/* The probability to use surface guiding (i.e., diffuse sampling prob * guiding prob). */
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KERNEL_STRUCT_MEMBER(guiding, float, volume_guiding_sampling_prob, KERNEL_FEATURE_PATH_GUIDING)
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KERNEL_STRUCT_END(guiding)
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/******************************* Shadow linking *******************************/
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KERNEL_STRUCT_BEGIN(shadow_link)
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KERNEL_STRUCT_MEMBER(shadow_link, float, dedicated_light_weight, KERNEL_FEATURE_SHADOW_LINKING)
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/* Copy of primitive and object from the last main path intersection. */
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KERNEL_STRUCT_MEMBER(shadow_link, int, last_isect_prim, KERNEL_FEATURE_SHADOW_LINKING)
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KERNEL_STRUCT_MEMBER(shadow_link, int, last_isect_object, KERNEL_FEATURE_SHADOW_LINKING)
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KERNEL_STRUCT_END(shadow_link)
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