2bd06093c7
Applies thin film iridescence to metals in Metallic BSDF and Principled BSDF. To get the complex IOR values for each spectral band from F82 Tint colors, the code uses the parametrization from "Artist Friendly Metallic Fresnel", where the g parameter is set to F82. This IOR is used to find the phase shift, but reflectance is still calculated with the F82 Tint formula after adjusting F0 for the film's IOR. Co-authored-by: Lukas Stockner <lukas@lukasstockner.de> Co-authored-by: Weizhen Huang <weizhen@blender.org> Co-authored-by: RobertMoerland <rmoerlandrj@gmail.com> Pull Request: https://projects.blender.org/blender/blender/pulls/141131
69 lines
2.1 KiB
GLSL
69 lines
2.1 KiB
GLSL
/* SPDX-FileCopyrightText: 2024 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#include "gpu_shader_math_vector_safe_lib.glsl"
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#include "gpu_shader_utildefines_lib.glsl"
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float3 fresnel_conductor(float cosi, float3 eta, float3 k)
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{
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float3 cosi_sqr = float3(cosi * cosi);
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float3 one = float3(1.0f);
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float3 tmp_f = (eta * eta) + (k * k);
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float3 tmp_two_eta_cosi = 2.0f * eta * float3(cosi);
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float3 tmp = tmp_f * cosi_sqr;
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float3 Rparl2 = (tmp - tmp_two_eta_cosi + one) / (tmp + tmp_two_eta_cosi + one);
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float3 Rperp2 = (tmp_f - tmp_two_eta_cosi + cosi_sqr) / (tmp_f + tmp_two_eta_cosi + cosi_sqr);
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return (Rparl2 + Rperp2) * 0.5f;
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}
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void node_bsdf_metallic(float4 base_color,
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float4 edge_tint,
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float3 ior,
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float3 extinction,
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float roughness,
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float anisotropy,
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float rotation,
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float3 N,
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float3 T,
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float weight,
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float thin_film_thickness,
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float thin_film_ior,
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const float do_multiscatter,
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const float use_complex_ior,
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out Closure result)
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{
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float3 F0 = base_color.rgb;
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float3 F82 = edge_tint.rgb;
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if (use_complex_ior != 0.0f) {
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/* Compute incidence at 0 and 82 degrees from conductor Fresnel. */
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F0 = fresnel_conductor(1.0f, ior, extinction);
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F82 = fresnel_conductor(1.0f / 7.0f, ior, extinction);
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}
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/* Clamp to match Cycles */
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F0 = saturate(F0);
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F82 = saturate(F82);
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roughness = saturate(roughness);
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/* Not used by EEVEE */
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/* anisotropy = saturate(anisotropy); */
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N = safe_normalize(N);
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float3 V = coordinate_incoming(g_data.P);
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float NV = dot(N, V);
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ClosureReflection reflection_data;
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reflection_data.N = N;
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reflection_data.roughness = roughness;
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float3 metallic_brdf;
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brdf_f82_tint_lut(F0, F82, NV, roughness, do_multiscatter != 0.0f, metallic_brdf);
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reflection_data.color = metallic_brdf;
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reflection_data.weight = weight;
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result = closure_eval(reflection_data);
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}
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