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| 1 | +// Copyright (C) 2018-2023 - DevSH Graphics Programming Sp. z O.O. |
| 2 | +// This file is part of the "Nabla Engine". |
| 3 | +// For conditions of distribution and use, see copyright notice in nabla.h |
| 4 | +#ifndef _NBL_BUILTIN_HLSL_BXDF_FRESNEL_INCLUDED_ |
| 5 | +#define _NBL_BUILTIN_HLSL_BXDF_FRESNEL_INCLUDED_ |
| 6 | + |
| 7 | +#include "nbl/builtin/hlsl/cpp_compat.hlsl" |
| 8 | +#include "nbl/builtin/hlsl/numbers.hlsl" |
| 9 | +#include "nbl/builtin/hlsl/vector_utils/vector_traits.hlsl" |
| 10 | +#include "nbl/builtin/hlsl/spirv_intrinsics/core.hlsl" |
| 11 | + |
| 12 | +namespace nbl |
| 13 | +{ |
| 14 | +namespace hlsl |
| 15 | +{ |
| 16 | + |
| 17 | +namespace bxdf |
| 18 | +{ |
| 19 | + |
| 20 | +namespace impl |
| 21 | +{ |
| 22 | +template<typename T> |
| 23 | +struct orientedEtas; |
| 24 | + |
| 25 | +template<> |
| 26 | +struct orientedEtas<float> |
| 27 | +{ |
| 28 | + static bool __call(NBL_REF_ARG(float) orientedEta, NBL_REF_ARG(float) rcpOrientedEta, float NdotI, float eta) |
| 29 | + { |
| 30 | + const bool backside = NdotI < 0.0; |
| 31 | + const float rcpEta = 1.0 / eta; |
| 32 | + orientedEta = backside ? rcpEta : eta; |
| 33 | + rcpOrientedEta = backside ? eta : rcpEta; |
| 34 | + return backside; |
| 35 | + } |
| 36 | +}; |
| 37 | + |
| 38 | +template<> |
| 39 | +struct orientedEtas<float32_t3> |
| 40 | +{ |
| 41 | + static bool __call(NBL_REF_ARG(float32_t3) orientedEta, NBL_REF_ARG(float32_t3) rcpOrientedEta, float NdotI, float32_t3 eta) |
| 42 | + { |
| 43 | + const bool backside = NdotI < 0.0; |
| 44 | + const float32_t3 rcpEta = (float32_t3)1.0 / eta; |
| 45 | + orientedEta = backside ? rcpEta:eta; |
| 46 | + rcpOrientedEta = backside ? eta:rcpEta; |
| 47 | + return backside; |
| 48 | + } |
| 49 | +}; |
| 50 | +} |
| 51 | + |
| 52 | +template<typename T NBL_FUNC_REQUIRES(is_scalar_v<T> || is_vector_v<T>) |
| 53 | +bool getOrientedEtas(NBL_REF_ARG(T) orientedEta, NBL_REF_ARG(T) rcpOrientedEta, scalar_type_t<T> NdotI, T eta) |
| 54 | +{ |
| 55 | + return impl::orientedEtas<T>::__call(orientedEta, rcpOrientedEta, NdotI, eta); |
| 56 | +} |
| 57 | + |
| 58 | + |
| 59 | +template <typename T NBL_FUNC_REQUIRES(concepts::Vectorial<T>) |
| 60 | +T reflect(T I, T N, typename vector_traits<T>::scalar_type NdotI) |
| 61 | +{ |
| 62 | + return N * 2.0f * NdotI - I; |
| 63 | +} |
| 64 | + |
| 65 | +template<typename T NBL_PRIMARY_REQUIRES(vector_traits<T>::Dimension == 3) |
| 66 | +struct refract |
| 67 | +{ |
| 68 | + using this_t = refract<T>; |
| 69 | + using vector_type = T; |
| 70 | + using scalar_type = typename vector_traits<T>::scalar_type; |
| 71 | + |
| 72 | + static this_t create(NBL_CONST_REF_ARG(vector_type) I, NBL_CONST_REF_ARG(vector_type) N, bool backside, scalar_type NdotI, scalar_type NdotI2, scalar_type rcpOrientedEta, scalar_type rcpOrientedEta2) |
| 73 | + { |
| 74 | + this_t retval; |
| 75 | + retval.I = I; |
| 76 | + retval.N = N; |
| 77 | + retval.backside = backside; |
| 78 | + retval.NdotI = NdotI; |
| 79 | + retval.NdotI2 = NdotI2; |
| 80 | + retval.rcpOrientedEta = rcpOrientedEta; |
| 81 | + retval.rcpOrientedEta2 = rcpOrientedEta2; |
| 82 | + return retval; |
| 83 | + } |
| 84 | + |
| 85 | + static this_t create(NBL_CONST_REF_ARG(vector_type) I, NBL_CONST_REF_ARG(vector_type) N, scalar_type NdotI, scalar_type eta) |
| 86 | + { |
| 87 | + this_t retval; |
| 88 | + retval.I = I; |
| 89 | + retval.N = N; |
| 90 | + scalar_type orientedEta; |
| 91 | + retval.backside = getOrientedEtas<scalar_type>(orientedEta, retval.rcpOrientedEta, NdotI, eta); |
| 92 | + retval.NdotI = NdotI; |
| 93 | + retval.NdotI2 = NdotI * NdotI; |
| 94 | + retval.rcpOrientedEta2 = retval.rcpOrientedEta * retval.rcpOrientedEta; |
| 95 | + return retval; |
| 96 | + } |
| 97 | + |
| 98 | + static this_t create(NBL_CONST_REF_ARG(vector_type) I, NBL_CONST_REF_ARG(vector_type) N, scalar_type eta) |
| 99 | + { |
| 100 | + this_t retval; |
| 101 | + retval.I = I; |
| 102 | + retval.N = N; |
| 103 | + retval.NdotI = dot<vector_type>(N, I); |
| 104 | + scalar_type orientedEta; |
| 105 | + retval.backside = getOrientedEtas<scalar_type>(orientedEta, retval.rcpOrientedEta, retval.NdotI, eta); |
| 106 | + retval.NdotI2 = retval.NdotI * retval.NdotI; |
| 107 | + retval.rcpOrientedEta2 = retval.rcpOrientedEta * retval.rcpOrientedEta; |
| 108 | + return retval; |
| 109 | + } |
| 110 | + |
| 111 | + static scalar_type computeNdotT(bool backside, scalar_type NdotI2, scalar_type rcpOrientedEta2) |
| 112 | + { |
| 113 | + scalar_type NdotT2 = rcpOrientedEta2 * NdotI2 + 1.0 - rcpOrientedEta2; |
| 114 | + scalar_type absNdotT = sqrt<scalar_type>(NdotT2); |
| 115 | + return backside ? absNdotT : -(absNdotT); |
| 116 | + } |
| 117 | + |
| 118 | + vector_type doRefract() |
| 119 | + { |
| 120 | + return N * (NdotI * rcpOrientedEta + computeNdotT(backside, NdotI2, rcpOrientedEta2)) - rcpOrientedEta * I; |
| 121 | + } |
| 122 | + |
| 123 | + static vector_type doReflectRefract(bool _refract, NBL_CONST_REF_ARG(vector_type) _I, NBL_CONST_REF_ARG(vector_type) _N, scalar_type _NdotI, scalar_type _NdotTorR, scalar_type _rcpOrientedEta) |
| 124 | + { |
| 125 | + return _N * (_NdotI * (_refract ? _rcpOrientedEta : 1.0f) + _NdotTorR) - _I * (_refract ? _rcpOrientedEta : 1.0f); |
| 126 | + } |
| 127 | + |
| 128 | + vector_type doReflectRefract(bool r) |
| 129 | + { |
| 130 | + const T NdotTorR = r ? computeNdotT(backside, NdotI2, rcpOrientedEta2) : NdotI; |
| 131 | + return doReflectRefract(r, I, N, NdotI, NdotTorR, rcpOrientedEta); |
| 132 | + } |
| 133 | + |
| 134 | + vector_type I; |
| 135 | + vector_type N; |
| 136 | + bool backside; |
| 137 | + scalar_type NdotI; |
| 138 | + scalar_type NdotI2; |
| 139 | + scalar_type rcpOrientedEta; |
| 140 | + scalar_type rcpOrientedEta2; |
| 141 | +}; |
| 142 | + |
| 143 | +} |
| 144 | + |
| 145 | +} |
| 146 | +} |
| 147 | + |
| 148 | +#endif |
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