overwrite DG concept, added Dcorrelated to ggx ndf with optimizations

keptsecret · keptsecret · commit 3519866e4273 · 2025-10-13T14:20:00.000+07:00
diff --git a/include/nbl/builtin/hlsl/bxdf/base/cook_torrance_base.hlsl b/include/nbl/builtin/hlsl/bxdf/base/cook_torrance_base.hlsl
@@ -119,6 +119,27 @@ struct getOrientedFresnel<F, true NBL_PARTIAL_REQ_BOT(fresnel::TwoSidedFresnel<F
         return fresnel.getReorientedFresnel(NdotV);
     }
 };
+
+template<class N, class LS, class Interaction, class MicrofacetCache>
+struct overwrite_DG
+{
+    using scalar_type = typename N::scalar_type;
+    using quant_type = typename N::quant_type;
+    using quant_query_type = typename N::quant_query_type;
+    using g2g1_query_type = typename N::g2g1_query_type;
+    NBL_CONSTEXPR_STATIC_INLINE bool HasOverwrite = ndf::NDF_CanOverwriteDG<N>;
+
+    template<typename C=bool_constant<!HasOverwrite> >
+    static enable_if_t<C::value && !HasOverwrite, void> __call(NBL_REF_ARG(scalar_type) DG, N ndf, NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction, NBL_CONST_REF_ARG(MicrofacetCache) cache)
+    {
+    }
+    template<typename C=bool_constant<HasOverwrite> >
+    static enable_if_t<C::value && HasOverwrite, void> __call(NBL_REF_ARG(scalar_type) DG, N ndf, NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction, NBL_CONST_REF_ARG(MicrofacetCache) cache)
+    {
+        quant_type dg = ndf.template Dcorrelated<LS, Interaction, MicrofacetCache>(query, quant_query, _sample, interaction, cache);
+        DG = dg.projectedLightMeasure;
+    }
+};
 }
 
 // N (NDF), F (fresnel)
@@ -148,16 +169,18 @@ struct SCookTorrance
         using quant_query_type = typename ndf_type::quant_query_type;
         quant_query_type qq = impl::quant_query_helper<ndf_type, fresnel_type, IsBSDF>::template __call<MicrofacetCache>(ndf, _f, cache);
 
+        using g2g1_query_type = typename ndf_type::g2g1_query_type;
+        g2g1_query_type gq = ndf.template createG2G1Query<sample_type, Interaction>(_sample, interaction);
+
         quant_type D = ndf.template D<sample_type, Interaction, MicrofacetCache>(qq, _sample, interaction, cache);
         scalar_type DG = D.projectedLightMeasure;
         if (D.microfacetMeasure < bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity))
-        {
-            using g2g1_query_type = typename ndf_type::g2g1_query_type;
-            g2g1_query_type gq = ndf.template createG2G1Query<sample_type, Interaction>(_sample, interaction);
             DG *= ndf.template correlated<sample_type, Interaction>(gq, _sample, interaction);
-        }
         else
             return hlsl::promote<spectral_type>(0.0);
+
+        impl::overwrite_DG<ndf_type, sample_type, Interaction, MicrofacetCache>::__call(DG, ndf, gq, qq, _sample, interaction, cache);
+
         scalar_type clampedVdotH = cache.getVdotH();
         NBL_IF_CONSTEXPR(IsBSDF)
             clampedVdotH = hlsl::abs(clampedVdotH);
diff --git a/include/nbl/builtin/hlsl/bxdf/ndf.hlsl b/include/nbl/builtin/hlsl/bxdf/ndf.hlsl
@@ -62,6 +62,34 @@ NBL_CONCEPT_END(
 #undef ndf
 #include <nbl/builtin/hlsl/concepts/__end.hlsl>
 
+#define NBL_CONCEPT_NAME NDF_CanOverwriteDG
+#define NBL_CONCEPT_TPLT_PRM_KINDS (typename)
+#define NBL_CONCEPT_TPLT_PRM_NAMES (T)
+#define NBL_CONCEPT_PARAM_0 (ndf, T)
+#define NBL_CONCEPT_PARAM_1 (quant_query, typename T::quant_query_type)
+#define NBL_CONCEPT_PARAM_2 (_sample, dummy_impl::sample_t)
+#define NBL_CONCEPT_PARAM_3 (interaction, dummy_impl::interaction_t)
+#define NBL_CONCEPT_PARAM_4 (cache, dummy_impl::cache_t)
+#define NBL_CONCEPT_PARAM_5 (g2_query, typename T::g2g1_query_type)
+NBL_CONCEPT_BEGIN(6)
+#define ndf NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_0
+#define quant_query NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_1
+#define _sample NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_2
+#define interaction NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_3
+#define cache NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_4
+#define g2_query NBL_CONCEPT_PARAM_T NBL_CONCEPT_PARAM_5
+NBL_CONCEPT_END(
+    ((NBL_CONCEPT_REQ_TYPE_ALIAS_CONCEPT)(NDF, T))
+    ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ndf.template Dcorrelated<dummy_impl::sample_t, dummy_impl::interaction_t, dummy_impl::cache_t>(g2_query, quant_query, _sample, interaction, cache)), ::nbl::hlsl::is_same_v, typename T::quant_type))
+);
+#undef g2_query
+#undef cache
+#undef interaction
+#undef _sample
+#undef quant_query
+#undef ndf
+#include <nbl/builtin/hlsl/concepts/__end.hlsl>
+
 
 #define NBL_HLSL_BXDF_ANISOTROPIC_COND_DECLS(IS_ANISO) template<class Interaction>\
 NBL_CONSTEXPR_STATIC_INLINE bool RequiredInteraction = IS_ANISO ? surface_interactions::Anisotropic<Interaction> : surface_interactions::Isotropic<Interaction>;\
diff --git a/include/nbl/builtin/hlsl/bxdf/ndf/ggx.hlsl b/include/nbl/builtin/hlsl/bxdf/ndf/ggx.hlsl
@@ -260,29 +260,55 @@ struct GGX
     quant_type D(NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction, NBL_CONST_REF_ARG(MicrofacetCache) cache)
     {
         scalar_type d = __ndf_base.template D<MicrofacetCache>(cache);
+        return createDualMeasureQuantity<T, reflect_refract, quant_query_type>(d, interaction.getNdotV(BxDFClampMode::BCM_ABS), _sample.getNdotL(BxDFClampMode::BCM_ABS), quant_query);
+    }
+
+    template<class LS, class Interaction NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction>)
+    quant_type DG1(NBL_CONST_REF_ARG(dg1_query_type) query, NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction)
+    {
+        scalar_type dg1_over_2NdotV = query.getNdfwoNumerator() * query.getG1over2NdotV();
         quant_type dmq;
-        dmq.microfacetMeasure = d;
+        dmq.microfacetMeasure = scalar_type(2.0) * interaction.getNdotV(_clamp) * dg1_over_2NdotV;
 
         NBL_IF_CONSTEXPR(SupportsTransmission)
         {
             const scalar_type VdotHLdotH = quant_query.getVdotHLdotH();
             const bool transmitted = reflect_refract==MTT_REFRACT || (reflect_refract!=MTT_REFLECT && VdotHLdotH < scalar_type(0.0));
-            scalar_type NdotL_over_denominator = _sample.getNdotL(BxDFClampMode::BCM_ABS);
+            dmq.projectedLightMeasure = hlsl::mix(scalar_type(0.5),scalar_type(2.0),transmitted) * dg1_over_2NdotV;
             if (transmitted)
-                    NdotL_over_denominator *= scalar_type(4.0) * VdotHLdotH * quant_query.getNeg_rcp2_VdotH_etaLdotH();
-            dmq.projectedLightMeasure = d * NdotL_over_denominator;
+                dmq.projectedLightMeasure *= VdotHLdotH * quant_query.getNeg_rcp2_VdotH_etaLdotH();
         }
         else
-            dmq.projectedLightMeasure = d * _sample.getNdotL(BxDFClampMode::BCM_ABS);
+            dmq.projectedLightMeasure = scalar_type(0.5) * dg1_over_2NdotV;
         return dmq;
     }
 
     template<class LS, class Interaction NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction>)
-    quant_type DG1(NBL_CONST_REF_ARG(dg1_query_type) query, NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction)
+    scalar_type correlated_wo_numerator(NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction)
+    {
+        // without numerator, numerator is 2 * NdotV * NdotL, we factor out 4 * NdotV * NdotL, hence 0.5
+        scalar_type Vterm = _sample.getNdotL(_clamp) * query.getDevshV();
+        scalar_type Lterm = interaction.getNdotV(_clamp) * query.getDevshL();
+        return scalar_type(0.5) / (Vterm + Lterm);
+    }
+
+    template<class LS, class Interaction NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction>)
+    scalar_type correlated(NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction)
+    {
+        return scalar_type(4.0) * interaction.getNdotV(_clamp) * _sample.getNdotL(_clamp) * correlated_wo_numerator<LS, Interaction>(query, _sample, interaction);
+    }
+
+    template<class LS, class Interaction, class MicrofacetCache NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction> && RequiredMicrofacetCache<MicrofacetCache>)
+    quant_type Dcorrelated(NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(quant_query_type) quant_query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction, NBL_CONST_REF_ARG(MicrofacetCache) cache)
     {
-        scalar_type dg1 = scalar_type(0.5) * query.getNdfwoNumerator() * query.getG1over2NdotV();
+        scalar_type dg = __ndf_base.template D<MicrofacetCache>(cache);
+        if (dg < bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity))
+            dg *= correlated_wo_numerator<LS, Interaction>(query, _sample, interaction);
+        else
+            dg = scalar_type(0.0);
+
         quant_type dmq;
-        dmq.microfacetMeasure = dg1;  // note: microfacetMeasure/4NdotV
+        dmq.microfacetMeasure = dg;
 
         NBL_IF_CONSTEXPR(SupportsTransmission)
         {
@@ -291,22 +317,13 @@ struct GGX
             scalar_type NdotL_over_denominator = _sample.getNdotL(BxDFClampMode::BCM_ABS);
             if (transmitted)
                     NdotL_over_denominator *= scalar_type(4.0) * VdotHLdotH * quant_query.getNeg_rcp2_VdotH_etaLdotH();
-            dmq.projectedLightMeasure = dg1;// TODO: figure this out * NdotL_over_denominator;
+            dmq.projectedLightMeasure = dg * NdotL_over_denominator;
         }
         else
-            dmq.projectedLightMeasure = dg1;// TODO: figure this out * _sample.getNdotL(BxDFClampMode::BCM_ABS);
+            dmq.projectedLightMeasure = dg * _sample.getNdotL(BxDFClampMode::BCM_ABS);
         return dmq;
     }
 
-    template<class LS, class Interaction NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction>)
-    scalar_type correlated(NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction)
-    {
-        // without numerator, numerator is 2 * NdotV * NdotL, we factor out 4 * NdotV * NdotL, hence 0.5
-        scalar_type Vterm = _sample.getNdotL(_clamp) * query.getDevshV();
-        scalar_type Lterm = interaction.getNdotV(_clamp) * query.getDevshL();
-        return scalar_type(0.5) / (Vterm + Lterm);
-    }
-
     template<class LS, class Interaction, class MicrofacetCache NBL_FUNC_REQUIRES(LightSample<LS> && RequiredInteraction<Interaction> && RequiredMicrofacetCache<MicrofacetCache>)
     scalar_type G2_over_G1(NBL_CONST_REF_ARG(g2g1_query_type) query, NBL_CONST_REF_ARG(LS) _sample, NBL_CONST_REF_ARG(Interaction) interaction, NBL_CONST_REF_ARG(MicrofacetCache) cache)
     {
