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Cycles: Add Metallic Tint to Principled BSDF using F82-Tint model 

With the default value, this is backwards-compatible.

Ref #99447

Pull Request: https://projects.blender.org/blender/blender/pulls/112551
This commit is contained in:
Lukas Stockner 2023-09-17 01:14:51 +02:00 committed by Brecht Van Lommel
parent 7eead8912d
commit 86156566a7
10 changed files with 159 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
intern/cycles/kernel/closure/bsdf_microfacet.h
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@ -26,6 +26,7 @@ enum MicrofacetFresnel {
DIELECTRIC_TINT, /* used by the OSL MaterialX closures */
CONDUCTOR,
GENERALIZED_SCHLICK,
F82_TINT,
};
typedef struct FresnelDielectricTint {
@ -46,6 +47,13 @@ typedef struct FresnelGeneralizedSchlick {
float exponent;
} FresnelGeneralizedSchlick;
typedef struct FresnelF82Tint {
/* Perpendicular reflectivity. */
Spectrum f0;
/* Precomputed (1-cos)^6 factor for edge tint. */
Spectrum b;
} FresnelF82Tint;
typedef struct MicrofacetBsdf {
SHADER_CLOSURE_BASE;
@ -236,6 +244,17 @@ ccl_device_forceinline void microfacet_fresnel(ccl_private const MicrofacetBsdf
*r_reflectance = fresnel_conductor(cos_theta_i, fresnel->n, fresnel->k);
*r_transmittance = zero_spectrum();
}
else if (bsdf->fresnel_type == MicrofacetFresnel::F82_TINT) {
/* F82-Tint model, described in "Novel aspects of the Adobe Standard Material" by Kutz et al.
* Essentially, this is the usual Schlick Fresnel with an additional cosI*(1-cosI)^6
* term which modulates the reflectivity around acos(1/7) degrees (ca. 82°). */
ccl_private FresnelF82Tint *fresnel = (ccl_private FresnelF82Tint *)bsdf->fresnel;
const float mu = saturatef(1.0f - cos_theta_i);
const float mu5 = sqr(sqr(mu)) * mu;
const Spectrum F_schlick = mix(fresnel->f0, one_spectrum(), mu5);
*r_reflectance = saturate(F_schlick - fresnel->b * cos_theta_i * mu5 * mu);
*r_transmittance = zero_spectrum();
}
else if (bsdf->fresnel_type == MicrofacetFresnel::GENERALIZED_SCHLICK) {
ccl_private FresnelGeneralizedSchlick *fresnel = (ccl_private FresnelGeneralizedSchlick *)
bsdf->fresnel;
@ -379,6 +398,14 @@ ccl_device Spectrum bsdf_microfacet_estimate_albedo(KernelGlobals kg,
}
reflectance = mix(fresnel->f0, fresnel->f90, s) * fresnel->reflection_tint;
}
else if (bsdf->fresnel_type == MicrofacetFresnel::F82_TINT) {
ccl_private FresnelF82Tint *fresnel = (ccl_private FresnelF82Tint *)bsdf->fresnel;
float rough = sqrtf(sqrtf(bsdf->alpha_x * bsdf->alpha_y));
const float s = lookup_table_read_3D(
kg, rough, cos_NI, 0.5f, kernel_data.tables.ggx_gen_schlick_s, 16, 16, 16);
/* TODO: Precompute B factor term and account for it here. */
reflectance = mix(fresnel->f0, one_spectrum(), s);
}
return reflectance + transmittance;
}
@ -738,6 +765,7 @@ ccl_device void bsdf_microfacet_setup_fresnel_generalized_schlick(
ccl_private FresnelGeneralizedSchlick *fresnel,
const bool preserve_energy)
{
fresnel->f0 = saturate(fresnel->f0);
bsdf->fresnel_type = MicrofacetFresnel::GENERALIZED_SCHLICK;
bsdf->fresnel = fresnel;
bsdf->sample_weight *= average(bsdf_microfacet_estimate_albedo(kg, sd, bsdf, true, true));
@ -780,6 +808,40 @@ ccl_device void bsdf_microfacet_setup_fresnel_generalized_schlick(
}
}
ccl_device void bsdf_microfacet_setup_fresnel_f82_tint(KernelGlobals kg,
ccl_private MicrofacetBsdf *bsdf,
ccl_private const ShaderData *sd,
ccl_private FresnelF82Tint *fresnel,
const Spectrum f82_tint,
const bool preserve_energy)
{
if (isequal(f82_tint, one_spectrum())) {
fresnel->b = zero_spectrum();
}
else {
/* Precompute the F82 term factor for the Fresnel model.
* In the classic F82 model, the F82 input directly determines the value of the Fresnel
* model at ~82°, similar to F0 and F90.
* With F82-Tint, on the other hand, the value at 82° is the value of the classic Schlick
* model multiplied by the tint input.
* Therefore, the factor follows by setting F82Tint(cosI) = FSchlick(cosI) - b*cosI*(1-cosI)^6
* and F82Tint(acos(1/7)) = FSchlick(acos(1/7)) * f82_tint and solving for b. */
const float f = 6.0f / 7.0f;
const float f5 = sqr(sqr(f)) * f;
const Spectrum F_schlick = mix(fresnel->f0, one_spectrum(), f5);
fresnel->b = F_schlick * (7.0f / (f5 * f)) * (one_spectrum() - f82_tint);
}
bsdf->fresnel_type = MicrofacetFresnel::F82_TINT;
bsdf->fresnel = fresnel;
bsdf->sample_weight *= average(bsdf_microfacet_estimate_albedo(kg, sd, bsdf, true, true));
if (preserve_energy) {
Spectrum Fss = mix(fresnel->f0, one_spectrum(), 1.0f / 21.0f) - fresnel->b * (1.0f / 126.0f);
microfacet_ggx_preserve_energy(kg, bsdf, sd, Fss);
}
}
ccl_device void bsdf_microfacet_setup_fresnel_constant(KernelGlobals kg,
ccl_private MicrofacetBsdf *bsdf,
ccl_private const ShaderData *sd,

47
intern/cycles/kernel/osl/closures_setup.h
View File

@ -474,6 +474,53 @@ ccl_device void osl_closure_microfacet_setup(KernelGlobals kg,
/* Special-purpose Microfacet closures */
ccl_device void osl_closure_microfacet_f82_tint_setup(
KernelGlobals kg,
ccl_private ShaderData *sd,
uint32_t path_flag,
float3 weight,
ccl_private const MicrofacetF82TintClosure *closure,
float3 *layer_albedo)
{
if (osl_closure_skip(kg, sd, path_flag, LABEL_GLOSSY | LABEL_REFLECT)) {
return;
}
ccl_private MicrofacetBsdf *bsdf = (ccl_private MicrofacetBsdf *)bsdf_alloc(
sd, sizeof(MicrofacetBsdf), rgb_to_spectrum(weight));
if (!bsdf) {
return;
}
ccl_private FresnelF82Tint *fresnel = (ccl_private FresnelF82Tint *)closure_alloc_extra(
sd, sizeof(FresnelF82Tint));
if (!fresnel) {
return;
}
bsdf->N = maybe_ensure_valid_specular_reflection(sd, closure->N);
bsdf->alpha_x = closure->alpha_x;
bsdf->alpha_y = closure->alpha_y;
bsdf->ior = 0.0f;
bsdf->T = closure->T;
bool preserve_energy = false;
/* Beckmann */
if (closure->distribution == make_string("beckmann", 14712237670914973463ull)) {
sd->flag |= bsdf_microfacet_beckmann_setup(bsdf);
}
/* GGX (either single- or multi-scattering) */
else {
sd->flag |= bsdf_microfacet_ggx_setup(bsdf);
preserve_energy = (closure->distribution == make_string("multi_ggx", 16842698693386468366ull));
}
fresnel->f0 = rgb_to_spectrum(closure->f0);
bsdf_microfacet_setup_fresnel_f82_tint(
kg, bsdf, sd, fresnel, rgb_to_spectrum(closure->f82), preserve_energy);
}
ccl_device void osl_closure_microfacet_multi_ggx_glass_setup(
KernelGlobals kg,
ccl_private ShaderData *sd,

10
intern/cycles/kernel/osl/closures_template.h
View File

@ -84,6 +84,16 @@ OSL_CLOSURE_STRUCT_BEGIN(Microfacet, microfacet)
OSL_CLOSURE_STRUCT_MEMBER(Microfacet, INT, int, refract, NULL)
OSL_CLOSURE_STRUCT_END(Microfacet, microfacet)
OSL_CLOSURE_STRUCT_BEGIN(MicrofacetF82Tint, microfacet_f82_tint)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, STRING, DeviceString, distribution, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, VECTOR, packed_float3, N, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, VECTOR, packed_float3, T, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, FLOAT, float, alpha_x, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, FLOAT, float, alpha_y, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, VECTOR, packed_float3, f0, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetF82Tint, VECTOR, packed_float3, f82, NULL)
OSL_CLOSURE_STRUCT_END(MicrofacetF82Tint, microfacet)
OSL_CLOSURE_STRUCT_BEGIN(MicrofacetMultiGGXGlass, microfacet_multi_ggx_glass)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetMultiGGXGlass, VECTOR, packed_float3, N, NULL)
OSL_CLOSURE_STRUCT_MEMBER(MicrofacetMultiGGXGlass, FLOAT, float, alpha_x, NULL)

5
intern/cycles/kernel/osl/shaders/node_principled_bsdf.osl
View File

@ -16,6 +16,7 @@ shader node_principled_bsdf(string distribution = "multi_ggx",
float Metallic = 0.0,
float Specular = 0.5,
float SpecularTint = 0.0,
color MetallicTint = 1.0,
float Roughness = 0.5,
float Anisotropic = 0.0,
float AnisotropicRotation = 0.0,
@ -97,8 +98,8 @@ shader node_principled_bsdf(string distribution = "multi_ggx",
if (Metallic > 0.0) {
color f0 = BaseColor;
color f90 = color(1.0);
MetallicBSDF = generalized_schlick_bsdf(
Normal, T, color(1.0), color(0.0), alpha_x, alpha_y, f0, f90, 5.0, distribution);
MetallicBSDF = microfacet_f82_tint(
distribution, Normal, T, alpha_x, alpha_y, f0, MetallicTint);
BSDF = mix(BSDF, MetallicBSDF, clamp(Metallic, 0.0, 1.0));
}

3
intern/cycles/kernel/osl/shaders/stdcycles.h
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@ -26,6 +26,9 @@ closure color ashikhmin_velvet(normal N, float sigma) BUILTIN;
closure color sheen(normal N, float roughness) BUILTIN;
closure color ambient_occlusion() BUILTIN;
closure color microfacet_f82_tint(
string distribution, vector N, vector T, float ax, float ay, color f0, color f82) BUILTIN;
/* Needed to pass along the color for multi-scattering saturation adjustment,
* otherwise could be replaced by microfacet() */
closure color microfacet_multi_ggx_glass(normal N, float ag, float eta, color C) BUILTIN;

24
intern/cycles/kernel/svm/closure.h
View File

@ -78,7 +78,7 @@ ccl_device_noinline int svm_node_closure_bsdf(KernelGlobals kg,
sheen_offset, sheen_tint_offset, sheen_roughness_offset, coat_offset,
coat_roughness_offset, coat_ior_offset, eta_offset, transmission_offset,
anisotropic_rotation_offset, coat_tint_offset, coat_normal_offset, dummy, alpha_offset,
emission_strength_offset, emission_offset;
emission_strength_offset, emission_offset, metallic_tint_offset;
uint4 data_node2 = read_node(kg, &offset);
float3 T = stack_load_float3(stack, data_node.y);
@ -87,8 +87,11 @@ ccl_device_noinline int svm_node_closure_bsdf(KernelGlobals kg,
&roughness_offset,
&specular_tint_offset,
&anisotropic_offset);
svm_unpack_node_uchar4(
data_node.w, &sheen_offset, &sheen_tint_offset, &sheen_roughness_offset, &dummy);
svm_unpack_node_uchar4(data_node.w,
&sheen_offset,
&sheen_tint_offset,
&sheen_roughness_offset,
&metallic_tint_offset);
svm_unpack_node_uchar4(data_node2.x,
&eta_offset,
&transmission_offset,
@ -255,10 +258,10 @@ ccl_device_noinline int svm_node_closure_bsdf(KernelGlobals kg,
if (reflective_caustics && metallic > CLOSURE_WEIGHT_CUTOFF) {
ccl_private MicrofacetBsdf *bsdf = (ccl_private MicrofacetBsdf *)bsdf_alloc(
sd, sizeof(MicrofacetBsdf), metallic * weight);
ccl_private FresnelGeneralizedSchlick *fresnel =
(bsdf != NULL) ? (ccl_private FresnelGeneralizedSchlick *)closure_alloc_extra(
sd, sizeof(FresnelGeneralizedSchlick)) :
NULL;
ccl_private FresnelF82Tint *fresnel =
(bsdf != NULL) ?
(ccl_private FresnelF82Tint *)closure_alloc_extra(sd, sizeof(FresnelF82Tint)) :
NULL;
if (bsdf && fresnel) {
bsdf->N = valid_reflection_N;
@ -268,15 +271,12 @@ ccl_device_noinline int svm_node_closure_bsdf(KernelGlobals kg,
bsdf->alpha_y = alpha_y;
fresnel->f0 = rgb_to_spectrum(base_color);
fresnel->f90 = one_spectrum();
fresnel->exponent = 5.0f;
fresnel->reflection_tint = one_spectrum();
fresnel->transmission_tint = zero_spectrum();
const Spectrum f82 = rgb_to_spectrum(stack_load_float3(stack, metallic_tint_offset));
/* setup bsdf */
sd->flag |= bsdf_microfacet_ggx_setup(bsdf);
const bool is_multiggx = (distribution == CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID);
bsdf_microfacet_setup_fresnel_generalized_schlick(kg, bsdf, sd, fresnel, is_multiggx);
bsdf_microfacet_setup_fresnel_f82_tint(kg, bsdf, sd, fresnel, f82, is_multiggx);
/* Attenuate other components */
weight *= (1.0f - metallic);

4
intern/cycles/scene/shader_nodes.cpp
View File

@ -2708,6 +2708,7 @@ NODE_DEFINE(PrincipledBsdfNode)
SOCKET_IN_FLOAT(specular, "Specular", 0.0f);
SOCKET_IN_FLOAT(roughness, "Roughness", 0.5f);
SOCKET_IN_FLOAT(specular_tint, "Specular Tint", 0.0f);
SOCKET_IN_COLOR(metallic_tint, "Metallic Tint", one_float3());
SOCKET_IN_FLOAT(anisotropic, "Anisotropic", 0.0f);
SOCKET_IN_FLOAT(sheen, "Sheen", 0.0f);
SOCKET_IN_FLOAT(sheen_roughness, "Sheen Roughness", 0.5f);
@ -2806,6 +2807,7 @@ void PrincipledBsdfNode::compile(SVMCompiler &compiler)
int specular_offset = compiler.stack_assign(input("Specular"));
int roughness_offset = compiler.stack_assign(input("Roughness"));
int specular_tint_offset = compiler.stack_assign(input("Specular Tint"));
int metallic_tint_offset = compiler.stack_assign(input("Metallic Tint"));
int anisotropic_offset = compiler.stack_assign(input("Anisotropic"));
int sheen_offset = compiler.stack_assign(input("Sheen"));
int sheen_roughness_offset = compiler.stack_assign(input("Sheen Roughness"));
@ -2839,7 +2841,7 @@ void PrincipledBsdfNode::compile(SVMCompiler &compiler)
compiler.encode_uchar4(
specular_offset, roughness_offset, specular_tint_offset, anisotropic_offset),
compiler.encode_uchar4(
sheen_offset, sheen_tint_offset, sheen_roughness_offset, SVM_STACK_INVALID));
sheen_offset, sheen_tint_offset, sheen_roughness_offset, metallic_tint_offset));
compiler.add_node(
compiler.encode_uchar4(

1
intern/cycles/scene/shader_nodes.h
View File

@ -528,6 +528,7 @@ class PrincipledBsdfNode : public BsdfBaseNode {
NODE_SOCKET_API(float, specular)
NODE_SOCKET_API(float, roughness)
NODE_SOCKET_API(float, specular_tint)
NODE_SOCKET_API(float3, metallic_tint)
NODE_SOCKET_API(float, anisotropic)
NODE_SOCKET_API(float, sheen)
NODE_SOCKET_API(float, sheen_roughness)

1
source/blender/gpu/shaders/material/gpu_shader_material_principled.glsl
View File

@ -31,6 +31,7 @@ void node_bsdf_principled(vec4 base_color,
vec3 subsurface_radius,
float subsurface_ior,
float subsurface_anisotropy,
vec4 metallic_tint,
float specular,
float specular_tint,
float anisotropic,

32
source/blender/nodes/shader/nodes/node_shader_bsdf_principled.cc
View File

@ -104,32 +104,34 @@ static void node_declare(NodeDeclarationBuilder &b)
.draw_buttons([](uiLayout *layout, bContext * /*C*/, PointerRNA *ptr) {
uiItemR(layout, ptr, "distribution", UI_ITEM_R_SPLIT_EMPTY_NAME, "", ICON_NONE);
});
spec.add_input<decl::Color>("Metallic Tint").default_value({1.0f, 1.0f, 1.0f, 1.0f});
#define SOCK_METALLIC_TINT_ID 13
spec.add_input<decl::Float>("Specular")
.default_value(0.5f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR);
#define SOCK_SPECULAR_ID 13
#define SOCK_SPECULAR_ID 14
spec.add_input<decl::Float>("Specular Tint")
.default_value(0.0f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR);
#define SOCK_SPECULAR_TINT_ID 14
#define SOCK_SPECULAR_TINT_ID 15
spec.add_input<decl::Float>("Anisotropic")
.default_value(0.0f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR);
#define SOCK_ANISOTROPIC_ID 15
#define SOCK_ANISOTROPIC_ID 16
spec.add_input<decl::Float>("Anisotropic Rotation")
.default_value(0.0f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR);
#define SOCK_ANISOTROPIC_ROTATION_ID 16
#define SOCK_ANISOTROPIC_ROTATION_ID 17
spec.add_input<decl::Vector>("Tangent").hide_value();
#define SOCK_TANGENT_ID 17
#define SOCK_TANGENT_ID 18
/* Panel for Coat settings. */
PanelDeclarationBuilder &coat = b.add_panel("Coat").default_closed(true);
@ -141,14 +143,14 @@ static void node_declare(NodeDeclarationBuilder &b)
.description(
"Controls the intensity of the coat layer, both the reflection and the tinting. "
"Typically should be zero or one for physically-based materials");
#define SOCK_COAT_ID 18
#define SOCK_COAT_ID 19
coat.add_input<decl::Float>("Coat Roughness")
.default_value(0.03f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR)
.description("The roughness of the coat layer");
#define SOCK_COAT_ROUGHNESS_ID 19
#define SOCK_COAT_ROUGHNESS_ID 20
coat.add_input<decl::Float>("Coat IOR")
.default_value(1.5f)
.min(1.0f)
@ -156,37 +158,37 @@ static void node_declare(NodeDeclarationBuilder &b)
.description(
"The index of refraction of the coat layer "
"(affects its reflectivity as well as the falloff of coat tinting)");
#define SOCK_COAT_IOR_ID 20
#define SOCK_COAT_IOR_ID 21
coat.add_input<decl::Color>("Coat Tint")
.default_value({1.0f, 1.0f, 1.0f, 1.0f})
.description(
"Adds a colored tint to the coat layer by modeling absorption in the layer. "
"Saturation increases at shallower angles, as the light travels farther "
"through the medium (depending on the Coat IOR)");
#define SOCK_COAT_TINT_ID 21
#define SOCK_COAT_TINT_ID 22
coat.add_input<decl::Vector>("Coat Normal").hide_value();
#define SOCK_COAT_NORMAL_ID 22
#define SOCK_COAT_NORMAL_ID 23
/* Panel for Sheen settings. */
PanelDeclarationBuilder &sheen = b.add_panel("Sheen").default_closed(true);
sheen.add_input<decl::Float>("Sheen").default_value(0.0f).min(0.0f).max(1.0f).subtype(
PROP_FACTOR);
#define SOCK_SHEEN_ID 23
#define SOCK_SHEEN_ID 24
sheen.add_input<decl::Float>("Sheen Roughness")
.default_value(0.5f)
.min(0.0f)
.max(1.0f)
.subtype(PROP_FACTOR);
#define SOCK_SHEEN_ROUGHNESS_ID 24
#define SOCK_SHEEN_ROUGHNESS_ID 25
sheen.add_input<decl::Color>("Sheen Tint").default_value({1.0f, 1.0f, 1.0f, 1.0f});
#define SOCK_SHEEN_TINT_ID 25
#define SOCK_SHEEN_TINT_ID 26
/* Panel for Emission settings. */
PanelDeclarationBuilder &emis = b.add_panel("Emission").default_closed(true);
emis.add_input<decl::Color>("Emission").default_value({1.0f, 1.0f, 1.0f, 1.0f});
#define SOCK_EMISSION_ID 26
#define SOCK_EMISSION_ID 27
emis.add_input<decl::Float>("Emission Strength").default_value(0.0).min(0.0f).max(1000000.0f);
#define SOCK_EMISSION_STRENGTH_ID 27
#define SOCK_EMISSION_STRENGTH_ID 28
}
static void node_shader_init_principled(bNodeTree * /*ntree*/, bNode *node)