From 1979176088047794813399baf85ff496c4fe456e Mon Sep 17 00:00:00 2001 From: Lukas Stockner Date: Wed, 21 Jun 2017 02:57:58 +0200 Subject: Cycles: Fix excessive sampling weight of glossy Principled BSDF components If there was any specularity in the Principled BSDF, it would get a sampling weight of one regardless of its actual impact. This commit makes Cycles estimate the contribution of the component and adjust the weighting accordingly, which greatly improves the noise characteristics of the Principled BSDF in many cases. Note that this commit might slightly change the brightness of areas when using MultiGGX and high roughnesses, but the new brightness is more accurate and closer to the result of Branched Path Tracing. See T51836 for details. Differential Revision: https://developer.blender.org/D2677 --- intern/cycles/kernel/closure/bsdf_microfacet.h | 18 +++++++++++++++--- intern/cycles/kernel/closure/bsdf_microfacet_multi.h | 18 +++++++++++++++--- 2 files changed, 30 insertions(+), 6 deletions(-) (limited to 'intern/cycles/kernel/closure') diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h index 30cc8b90330..b12e248f0a3 100644 --- a/intern/cycles/kernel/closure/bsdf_microfacet.h +++ b/intern/cycles/kernel/closure/bsdf_microfacet.h @@ -288,12 +288,16 @@ ccl_device int bsdf_microfacet_ggx_setup(MicrofacetBsdf *bsdf) return SD_BSDF|SD_BSDF_HAS_EVAL; } -ccl_device int bsdf_microfacet_ggx_fresnel_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_ggx_fresnel_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { bsdf->extra->cspec0.x = saturate(bsdf->extra->cspec0.x); bsdf->extra->cspec0.y = saturate(bsdf->extra->cspec0.y); bsdf->extra->cspec0.z = saturate(bsdf->extra->cspec0.z); + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= F; + bsdf->alpha_x = saturate(bsdf->alpha_x); bsdf->alpha_y = bsdf->alpha_x; @@ -302,12 +306,16 @@ ccl_device int bsdf_microfacet_ggx_fresnel_setup(MicrofacetBsdf *bsdf) return SD_BSDF|SD_BSDF_HAS_EVAL; } -ccl_device int bsdf_microfacet_ggx_clearcoat_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_ggx_clearcoat_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { bsdf->extra->cspec0.x = saturate(bsdf->extra->cspec0.x); bsdf->extra->cspec0.y = saturate(bsdf->extra->cspec0.y); bsdf->extra->cspec0.z = saturate(bsdf->extra->cspec0.z); + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= 0.25f * bsdf->extra->clearcoat * F; + bsdf->alpha_x = saturate(bsdf->alpha_x); bsdf->alpha_y = bsdf->alpha_x; @@ -343,12 +351,16 @@ ccl_device int bsdf_microfacet_ggx_aniso_setup(MicrofacetBsdf *bsdf) return SD_BSDF|SD_BSDF_HAS_EVAL; } -ccl_device int bsdf_microfacet_ggx_aniso_fresnel_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_ggx_aniso_fresnel_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { bsdf->extra->cspec0.x = saturate(bsdf->extra->cspec0.x); bsdf->extra->cspec0.y = saturate(bsdf->extra->cspec0.y); bsdf->extra->cspec0.z = saturate(bsdf->extra->cspec0.z); + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= F; + bsdf->alpha_x = saturate(bsdf->alpha_x); bsdf->alpha_y = saturate(bsdf->alpha_y); diff --git a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h index 165666d5368..22d0092093a 100644 --- a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h +++ b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h @@ -360,13 +360,17 @@ ccl_device int bsdf_microfacet_multi_ggx_aniso_setup(MicrofacetBsdf *bsdf) return bsdf_microfacet_multi_ggx_common_setup(bsdf); } -ccl_device int bsdf_microfacet_multi_ggx_aniso_fresnel_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_multi_ggx_aniso_fresnel_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { if(is_zero(bsdf->T)) bsdf->T = make_float3(1.0f, 0.0f, 0.0f); bsdf->type = CLOSURE_BSDF_MICROFACET_MULTI_GGX_FRESNEL_ID; + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= F; + return bsdf_microfacet_multi_ggx_common_setup(bsdf); } @@ -379,12 +383,16 @@ ccl_device int bsdf_microfacet_multi_ggx_setup(MicrofacetBsdf *bsdf) return bsdf_microfacet_multi_ggx_common_setup(bsdf); } -ccl_device int bsdf_microfacet_multi_ggx_fresnel_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_multi_ggx_fresnel_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { bsdf->alpha_y = bsdf->alpha_x; bsdf->type = CLOSURE_BSDF_MICROFACET_MULTI_GGX_FRESNEL_ID; + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= F; + return bsdf_microfacet_multi_ggx_common_setup(bsdf); } @@ -489,7 +497,7 @@ ccl_device int bsdf_microfacet_multi_ggx_glass_setup(MicrofacetBsdf *bsdf) return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_NEEDS_LCG; } -ccl_device int bsdf_microfacet_multi_ggx_glass_fresnel_setup(MicrofacetBsdf *bsdf) +ccl_device int bsdf_microfacet_multi_ggx_glass_fresnel_setup(MicrofacetBsdf *bsdf, const ShaderData *sd) { bsdf->alpha_x = clamp(bsdf->alpha_x, 1e-4f, 1.0f); bsdf->alpha_y = bsdf->alpha_x; @@ -503,6 +511,10 @@ ccl_device int bsdf_microfacet_multi_ggx_glass_fresnel_setup(MicrofacetBsdf *bsd bsdf->type = CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_FRESNEL_ID; + float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior); + float F = average(interpolate_fresnel_color(sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0)); + bsdf->sample_weight *= F; + return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_NEEDS_LCG; 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