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fixes more nan problems + a few bugs in iridescent fresnel
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-29
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2 files changed

+44
-29
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‎examples_tests‎

‎include/nbl/builtin/hlsl/bxdf/fresnel.hlsl‎

Lines changed: 43 additions & 28 deletions
Original file line numberDiff line numberDiff line change
@@ -508,25 +508,26 @@ struct iridescent_helper
508508
using scalar_type = typename vector_traits<T>::scalar_type;
509509
using vector_type = T;
510510

511-
// returns reflectance R = (rp, rs), phi is the phase shift for each plane of polarization (p,s)
512-
static void phase_shift(const vector_type orientedEta, const vector_type orientedEtak, const vector_type cosTheta, NBL_REF_ARG(vector_type) phiS, NBL_REF_ARG(vector_type) phiP)
511+
// returns phi, the phase shift for each plane of polarization (p,s)
512+
static void phase_shift(const vector_type ior1, const vector_type ior2, const vector_type iork2, const vector_type cosTheta, NBL_REF_ARG(vector_type) phiS, NBL_REF_ARG(vector_type) phiP)
513513
{
514-
vector_type cosTheta_2 = cosTheta * cosTheta;
515-
vector_type sinTheta2 = hlsl::promote<vector_type>(1.0) - cosTheta_2;
516-
const vector_type eta2 = orientedEta*orientedEta;
517-
const vector_type etak2 = orientedEtak*orientedEtak;
514+
const vector_type cosTheta2 = cosTheta * cosTheta;
515+
const vector_type sinTheta2 = hlsl::promote<vector_type>(1.0) - cosTheta2;
516+
const vector_type ior1_2 = ior1*ior1;
517+
const vector_type ior2_2 = ior2*ior2;
518+
const vector_type iork2_2 = iork2*iork2;
518519

519-
vector_type z = eta2 - etak2 - sinTheta2;
520-
vector_type w = hlsl::sqrt(z * z + scalar_type(4.0) * eta2 * eta2 * etak2);
521-
vector_type a2 = (z + w) * hlsl::promote<vector_type>(0.5);
522-
vector_type b2 = (w - z) * hlsl::promote<vector_type>(0.5);
523-
vector_type b = hlsl::sqrt(b2);
520+
const vector_type z = ior2_2 * (hlsl::promote<vector_type>(1.0) - iork2_2) - ior1_2 * sinTheta2;
521+
const vector_type w = hlsl::sqrt(z*z + scalar_type(4.0) * ior2_2 * ior2_2 * iork2_2);
522+
const vector_type a2 = hlsl::max(z + w, hlsl::promote<vector_type>(0.0)) * hlsl::promote<vector_type>(0.5);
523+
const vector_type b2 = hlsl::max(w - z, hlsl::promote<vector_type>(0.0)) * hlsl::promote<vector_type>(0.5);
524+
const vector_type a = hlsl::sqrt(a2);
525+
const vector_type b = hlsl::sqrt(b2);
524526

525-
const vector_type t0 = eta2 + etak2;
526-
const vector_type t1 = t0 * cosTheta_2;
527-
528-
phiS = hlsl::atan2(hlsl::promote<vector_type>(2.0) * b * cosTheta, a2 + b2 - cosTheta_2);
529-
phiP = hlsl::atan2(hlsl::promote<vector_type>(2.0) * eta2 * cosTheta * (hlsl::promote<vector_type>(2.0) * orientedEtak * hlsl::sqrt(a2) - etak2 * b), t1 - a2 + b2);
527+
phiS = hlsl::atan2(scalar_type(2.0) * ior1 * b * cosTheta, a2 + b2 - ior1_2*cosTheta2);
528+
const vector_type k2_plus_one = hlsl::promote<vector_type>(1.0) + iork2_2;
529+
phiP = hlsl::atan2(scalar_type(2.0) * ior1 * ior2_2 * cosTheta * (scalar_type(2.0) * iork2 * a - (hlsl::promote<vector_type>(1.0) - iork2_2) * b),
530+
ior2_2 * cosTheta2 * k2_plus_one * k2_plus_one - ior1_2*(a2+b2));
530531
}
531532

532533
// Evaluation XYZ sensitivity curves in Fourier space
@@ -544,7 +545,8 @@ struct iridescent_helper
544545
}
545546

546547
template<typename Colorspace>
547-
static T __call(const vector_type _D, const vector_type eta12, const vector_type eta23, const vector_type etak23, const scalar_type clampedCosTheta)
548+
static T __call(const vector_type _D, const vector_type ior1, const vector_type ior2, const vector_type ior3, const vector_type iork3,
549+
const vector_type eta12, const vector_type eta23, const vector_type etak23, const scalar_type clampedCosTheta)
548550
{
549551
const vector_type wavelengths = vector_type(Colorspace::wavelength_R, Colorspace::wavelength_G, Colorspace::wavelength_B);
550552

@@ -593,8 +595,8 @@ struct iridescent_helper
593595
vector_type I = hlsl::promote<vector_type>(0.0);
594596

595597
// Evaluate the phase shift
596-
phase_shift(eta12, hlsl::promote<vector_type>(0.0), hlsl::promote<vector_type>(cosTheta_1), phi21p, phi21s);
597-
phase_shift(eta23, etak23, cosTheta_2, phi23p, phi23s);
598+
phase_shift(ior1, ior2, hlsl::promote<vector_type>(0.0), hlsl::promote<vector_type>(cosTheta_1), phi21s, phi21p);
599+
phase_shift(ior2, ior3, iork3, cosTheta_2, phi23s, phi23p);
598600
phi21p = hlsl::promote<vector_type>(numbers::pi<scalar_type>) - phi21p;
599601
phi21s = hlsl::promote<vector_type>(numbers::pi<scalar_type>) - phi21s;
600602

@@ -633,7 +635,7 @@ struct iridescent_helper
633635
I += Cm*Sm;
634636
}
635637

636-
return hlsl::max(colorspace::scRGB::FromXYZ(I), hlsl::promote<vector_type>(0.0)) * hlsl::promote<vector_type>(0.5);
638+
return hlsl::max(colorspace::scRGB::FromXYZ(I) * hlsl::promote<vector_type>(0.5), hlsl::promote<vector_type>(0.0));
637639
}
638640
};
639641

@@ -643,11 +645,11 @@ struct iridescent_base
643645
using scalar_type = typename vector_traits<T>::scalar_type;
644646
using vector_type = T;
645647

646-
vector_type getD() NBL_CONST_MEMBER_FUNC { return D; }
647-
vector_type getEta12() NBL_CONST_MEMBER_FUNC { return eta12; }
648-
vector_type getEta23() NBL_CONST_MEMBER_FUNC { return eta23; }
649-
650648
vector_type D;
649+
vector_type ior1;
650+
vector_type ior2;
651+
vector_type ior3;
652+
vector_type iork3;
651653
vector_type eta12; // outside (usually air 1.0) -> thin-film IOR
652654
vector_type eta23; // thin-film -> base material IOR
653655
};
@@ -679,6 +681,10 @@ struct Iridescent<T, false, Colorspace NBL_PARTIAL_REQ_BOT(concepts::FloatingPoi
679681
{
680682
this_t retval;
681683
retval.D = hlsl::promote<vector_type>(2.0 * params.Dinc) * params.ior2;
684+
retval.ior1 = params.ior1;
685+
retval.ior2 = params.ior2;
686+
retval.ior3 = params.ior3;
687+
retval.iork3 = params.iork3;
682688
retval.eta12 = params.ior2/params.ior1;
683689
retval.eta23 = params.ior3/params.ior2;
684690
retval.etak23 = params.iork3/params.ior2;
@@ -687,7 +693,8 @@ struct Iridescent<T, false, Colorspace NBL_PARTIAL_REQ_BOT(concepts::FloatingPoi
687693

688694
T operator()(const scalar_type clampedCosTheta) NBL_CONST_MEMBER_FUNC
689695
{
690-
return impl::iridescent_helper<T,false>::template __call<Colorspace>(base_type::getD(), base_type::getEta12(), base_type::getEta23(), getEtak23(), clampedCosTheta);
696+
return impl::iridescent_helper<T,false>::template __call<Colorspace>(base_type::D, base_type::ior1, base_type::ior2, base_type::ior3, base_type::iork3,
697+
base_type::eta12, base_type::eta23, getEtak23(), clampedCosTheta);
691698
}
692699

693700
OrientedEtaRcps<eta_type> getOrientedEtaRcps() NBL_CONST_MEMBER_FUNC
@@ -731,14 +738,19 @@ struct Iridescent<T, true, Colorspace NBL_PARTIAL_REQ_BOT(concepts::FloatingPoin
731738
{
732739
this_t retval;
733740
retval.D = hlsl::promote<vector_type>(2.0 * params.Dinc) * params.ior2;
741+
retval.ior1 = params.ior1;
742+
retval.ior2 = params.ior2;
743+
retval.ior3 = params.ior3;
744+
retval.iork3 = params.iork3;
734745
retval.eta12 = params.ior2/params.ior1;
735746
retval.eta23 = params.ior3/params.ior2;
736747
return retval;
737748
}
738749

739750
T operator()(const scalar_type clampedCosTheta) NBL_CONST_MEMBER_FUNC
740751
{
741-
return impl::iridescent_helper<T,true>::template __call<Colorspace>(base_type::getD(), base_type::getEta12(), base_type::getEta23(), getEtak23(), clampedCosTheta);
752+
return impl::iridescent_helper<T,true>::template __call<Colorspace>(base_type::D, base_type::ior1, base_type::ior2, base_type::ior3, getEtak23(),
753+
base_type::eta12, base_type::eta23, getEtak23(), clampedCosTheta);
742754
}
743755

744756
scalar_type getRefractionOrientedEta() NBL_CONST_MEMBER_FUNC { return base_type::eta23[0]; }
@@ -755,8 +767,11 @@ struct Iridescent<T, true, Colorspace NBL_PARTIAL_REQ_BOT(concepts::FloatingPoin
755767
const bool flip = NdotI < scalar_type(0.0);
756768
this_t orientedFresnel;
757769
orientedFresnel.D = base_type::D;
758-
orientedFresnel.eta12 = hlsl::mix(base_type::eta12, hlsl::promote<vector_type>(1.0)/base_type::eta12, flip);
759-
orientedFresnel.eta23 = hlsl::mix(base_type::eta23, hlsl::promote<vector_type>(1.0)/base_type::eta23, flip);
770+
orientedFresnel.ior1 = base_type::ior3;
771+
orientedFresnel.ior2 = base_type::ior2;
772+
orientedFresnel.ior3 = base_type::ior1;
773+
orientedFresnel.eta12 = hlsl::mix(base_type::eta12, hlsl::promote<vector_type>(1.0)/base_type::eta23, flip);
774+
orientedFresnel.eta23 = hlsl::mix(base_type::eta23, hlsl::promote<vector_type>(1.0)/base_type::eta12, flip);
760775
return orientedFresnel;
761776
}
762777

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