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Created concepts for samplers, added quotient_and_pdf variants to satisfy the concepts #1001

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f71610b
Created concepts for samplers, added quotient_and_pdf variants to sat…
karimsayedre Feb 18, 2026
0e0b0ad
revert bad formatting for hlsl sampling headers
karimsayedre Feb 25, 2026
3574d83
Separate warp sample types from quotient_and_pdf, add sample density …
karimsayedre Feb 25, 2026
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2 changes: 1 addition & 1 deletion examples_tests
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Submodule examples_tests updated 4 files
+54 −0 37_HLSLSamplingTests/CMakeLists.txt
+79 −0 37_HLSLSamplingTests/app_resources/test_compile.comp.hlsl
+121 −0 37_HLSLSamplingTests/main.cpp
+1 −0 CMakeLists.txt
32 changes: 16 additions & 16 deletions include/nbl/builtin/hlsl/sampling/basic.hlsl
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Expand Up @@ -18,29 +18,29 @@ namespace sampling
template<typename T NBL_PRIMARY_REQUIRES(concepts::FloatingPointLikeScalar<T>)
struct PartitionRandVariable
{
using floating_point_type = T;
using uint_type = unsigned_integer_of_size_t<sizeof(floating_point_type)>;
using floating_point_type = T;
using uint_type = unsigned_integer_of_size_t<sizeof(floating_point_type)>;

bool operator()(NBL_REF_ARG(floating_point_type) xi, NBL_REF_ARG(floating_point_type) rcpChoiceProb)
{
const floating_point_type NextULPAfterUnity = bit_cast<floating_point_type>(bit_cast<uint_type>(floating_point_type(1.0)) + uint_type(1u));
const bool pickRight = xi >= leftProb * NextULPAfterUnity;
bool operator()(NBL_REF_ARG(floating_point_type) xi, NBL_REF_ARG(floating_point_type) rcpChoiceProb)
{
const floating_point_type NextULPAfterUnity = bit_cast<floating_point_type>(bit_cast<uint_type>(floating_point_type(1.0)) + uint_type(1u));
const bool pickRight = xi >= leftProb * NextULPAfterUnity;

// This is all 100% correct taking into account the above NextULPAfterUnity
xi -= pickRight ? leftProb : floating_point_type(0.0);
// This is all 100% correct taking into account the above NextULPAfterUnity
xi -= pickRight ? leftProb : floating_point_type(0.0);

rcpChoiceProb = floating_point_type(1.0) / (pickRight ? (floating_point_type(1.0) - leftProb) : leftProb);
xi *= rcpChoiceProb;
rcpChoiceProb = floating_point_type(1.0) / (pickRight ? (floating_point_type(1.0) - leftProb) : leftProb);
xi *= rcpChoiceProb;

return pickRight;
}
return pickRight;
}

floating_point_type leftProb;
floating_point_type leftProb;
};


}
}
}
} // namespace sampling
} // namespace hlsl
} // namespace nbl

#endif
73 changes: 40 additions & 33 deletions include/nbl/builtin/hlsl/sampling/bilinear.hlsl
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Expand Up @@ -19,47 +19,54 @@ namespace sampling
template<typename T>
struct Bilinear
{
using scalar_type = T;
using vector2_type = vector<T, 2>;
using vector3_type = vector<T, 3>;
using vector4_type = vector<T, 4>;
using scalar_type = T;
using vector2_type = vector<T, 2>;
using vector3_type = vector<T, 3>;
using vector4_type = vector<T, 4>;

static Bilinear<T> create(const vector4_type bilinearCoeffs)
{
Bilinear<T> retval;
retval.bilinearCoeffs = bilinearCoeffs;
retval.twiceAreasUnderXCurve = vector2_type(bilinearCoeffs[0] + bilinearCoeffs[1], bilinearCoeffs[2] + bilinearCoeffs[3]);
return retval;
}
// BijectiveSampler concept types
using domain_type = vector2_type;
using codomain_type = vector2_type;
using density_type = scalar_type;
using sample_type = codomain_and_rcpPdf<codomain_type, density_type>;
using inverse_sample_type = domain_and_rcpPdf<domain_type, density_type>;

vector2_type generate(NBL_REF_ARG(scalar_type) rcpPdf, const vector2_type _u)
{
vector2_type u;
Linear<scalar_type> lineary = Linear<scalar_type>::create(twiceAreasUnderXCurve);
u.y = lineary.generate(_u.y);
static Bilinear<T> create(const vector4_type bilinearCoeffs)
{
Bilinear<T> retval;
retval.bilinearCoeffs = bilinearCoeffs;
retval.twiceAreasUnderXCurve = vector2_type(bilinearCoeffs[0] + bilinearCoeffs[1], bilinearCoeffs[2] + bilinearCoeffs[3]);
return retval;
}

const vector2_type ySliceEndPoints = vector2_type(nbl::hlsl::mix(bilinearCoeffs[0], bilinearCoeffs[2], u.y), nbl::hlsl::mix(bilinearCoeffs[1], bilinearCoeffs[3], u.y));
Linear<scalar_type> linearx = Linear<scalar_type>::create(ySliceEndPoints);
u.x = linearx.generate(_u.x);
vector2_type generate(NBL_REF_ARG(scalar_type) rcpPdf, const vector2_type _u)
{
vector2_type u;
Linear<scalar_type> lineary = Linear<scalar_type>::create(twiceAreasUnderXCurve);
u.y = lineary.generate(_u.y);

rcpPdf = (twiceAreasUnderXCurve[0] + twiceAreasUnderXCurve[1]) / (4.0 * nbl::hlsl::mix(ySliceEndPoints[0], ySliceEndPoints[1], u.x));
const vector2_type ySliceEndPoints = vector2_type(nbl::hlsl::mix(bilinearCoeffs[0], bilinearCoeffs[2], u.y), nbl::hlsl::mix(bilinearCoeffs[1], bilinearCoeffs[3], u.y));
Linear<scalar_type> linearx = Linear<scalar_type>::create(ySliceEndPoints);
u.x = linearx.generate(_u.x);

return u;
}
rcpPdf = (twiceAreasUnderXCurve[0] + twiceAreasUnderXCurve[1]) / (4.0 * nbl::hlsl::mix(ySliceEndPoints[0], ySliceEndPoints[1], u.x));

scalar_type pdf(const vector2_type u)
{
return 4.0 * nbl::hlsl::mix(nbl::hlsl::mix(bilinearCoeffs[0], bilinearCoeffs[1], u.x), nbl::hlsl::mix(bilinearCoeffs[2], bilinearCoeffs[3], u.x), u.y) / (bilinearCoeffs[0] + bilinearCoeffs[1] + bilinearCoeffs[2] + bilinearCoeffs[3]);
}
return u;
}

// unit square: x0y0 x1y0
// x0y1 x1y1
vector4_type bilinearCoeffs; // (x0y0, x0y1, x1y0, x1y1)
vector2_type twiceAreasUnderXCurve;
scalar_type pdf(const vector2_type u)
{
return 4.0 * nbl::hlsl::mix(nbl::hlsl::mix(bilinearCoeffs[0], bilinearCoeffs[1], u.x), nbl::hlsl::mix(bilinearCoeffs[2], bilinearCoeffs[3], u.x), u.y) / (bilinearCoeffs[0] + bilinearCoeffs[1] + bilinearCoeffs[2] + bilinearCoeffs[3]);
}

// unit square: x0y0 x1y0
// x0y1 x1y1
vector4_type bilinearCoeffs; // (x0y0, x0y1, x1y0, x1y1)
vector2_type twiceAreasUnderXCurve;
};

}
}
}
} // namespace sampling
} // namespace hlsl
} // namespace nbl

#endif
35 changes: 21 additions & 14 deletions include/nbl/builtin/hlsl/sampling/box_muller_transform.hlsl
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Expand Up @@ -7,6 +7,7 @@

#include "nbl/builtin/hlsl/math/functions.hlsl"
#include "nbl/builtin/hlsl/numbers.hlsl"
#include "nbl/builtin/hlsl/sampling/warp_and_pdf.hlsl"

namespace nbl
{
Expand All @@ -18,21 +19,27 @@ namespace sampling
template<typename T NBL_PRIMARY_REQUIRES(concepts::FloatingPointLikeScalar<T>)
struct BoxMullerTransform
{
using scalar_type = T;
using vector2_type = vector<T,2>;

vector2_type operator()(const vector2_type xi)
{
scalar_type sinPhi, cosPhi;
math::sincos<scalar_type>(2.0 * numbers::pi<scalar_type> * xi.y - numbers::pi<scalar_type>, sinPhi, cosPhi);
return vector2_type(cosPhi, sinPhi) * nbl::hlsl::sqrt(-2.0 * nbl::hlsl::log(xi.x)) * stddev;
}

T stddev;
using scalar_type = T;
using vector2_type = vector<T, 2>;

// ResamplableSampler concept types
using domain_type = vector2_type;
using codomain_type = vector2_type;
using density_type = scalar_type;
using sample_type = codomain_and_rcpPdf<codomain_type, density_type>;

vector2_type operator()(const vector2_type xi)
{
scalar_type sinPhi, cosPhi;
math::sincos<scalar_type>(2.0 * numbers::pi<scalar_type> * xi.y - numbers::pi<scalar_type>, sinPhi, cosPhi);
return vector2_type(cosPhi, sinPhi) * nbl::hlsl::sqrt(-2.0 * nbl::hlsl::log(xi.x)) * stddev;
}

T stddev;
};

}
}
}
} // namespace sampling
} // namespace hlsl
} // namespace nbl

#endif
55 changes: 29 additions & 26 deletions include/nbl/builtin/hlsl/sampling/concentric_mapping.hlsl
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Expand Up @@ -17,34 +17,37 @@ namespace sampling
{

template<typename T>
vector<T,2> concentricMapping(const vector<T,2> _u)
vector<T, 2> concentricMapping(const vector<T, 2> _u)
{
//map [0;1]^2 to [-1;1]^2
vector<T,2> u = 2.0f * _u - hlsl::promote<vector<T,2> >(1.0);

vector<T,2> p;
if (hlsl::all<vector<bool,2> >(glsl::equal(u, hlsl::promote<vector<T,2> >(0.0))))
p = hlsl::promote<vector<T,2> >(0.0);
else
{
T r;
T theta;
if (abs<T>(u.x) > abs<T>(u.y)) {
r = u.x;
theta = 0.25 * numbers::pi<T> * (u.y / u.x);
} else {
r = u.y;
theta = 0.5 * numbers::pi<T> - 0.25 * numbers::pi<T> * (u.x / u.y);
}

p = r * vector<T,2>(cos<T>(theta), sin<T>(theta));
}

return p;
//map [0;1]^2 to [-1;1]^2
vector<T, 2> u = 2.0f * _u - hlsl::promote<vector<T, 2> >(1.0);

vector<T, 2> p;
if (hlsl::all<vector<bool, 2> >(glsl::equal(u, hlsl::promote<vector<T, 2> >(0.0))))
p = hlsl::promote<vector<T, 2> >(0.0);
else
{
T r;
T theta;
if (abs<T>(u.x) > abs<T>(u.y))
{
r = u.x;
theta = 0.25 * numbers::pi<T> * (u.y / u.x);
}
else
{
r = u.y;
theta = 0.5 * numbers::pi<T> - 0.25 * numbers::pi<T> * (u.x / u.y);
}

p = r * vector<T, 2>(cos<T>(theta), sin<T>(theta));
}

return p;
}

}
}
}
} // namespace sampling
} // namespace hlsl
} // namespace nbl

#endif
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