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72 lines
2.5 KiB
72 lines
2.5 KiB
// David Eberly, Geometric Tools, Redmond WA 98052
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// Copyright (c) 1998-2021
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// Distributed under the Boost Software License, Version 1.0.
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// https://www.boost.org/LICENSE_1_0.txt
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// https://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
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// Version: 4.0.2019.08.13
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#pragma once
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#include <Mathematics/Logger.h>
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#include <Mathematics/Vector3.h>
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// Linear interpolation of a network of triangles whose vertices are of the
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// form (x,y,z,f(x,y,z)). The function samples are F[i] and represent
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// f(x[i],y[i],z[i]), where i is the index of the input vertex
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// (x[i],y[i],z[i]) to Delaunay3.
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//
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// The TetrahedronMesh interface must support the following:
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// int GetContainingTetrahedron(Vector3<Real> const&) const;
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// bool GetIndices(int, std::array<int, 4>&) const;
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// bool GetBarycentrics(int, Vector3<Real> const&, Real[4]) const;
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namespace gte
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{
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template <typename Real, typename TetrahedronMesh>
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class IntpLinearNonuniform3
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{
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public:
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// Construction.
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IntpLinearNonuniform3(TetrahedronMesh const& mesh, Real const* F)
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:
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mMesh(&mesh),
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mF(F)
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{
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LogAssert(mF != nullptr, "Invalid input.");
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}
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// Linear interpolation. The return value is 'true' if and only if
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// the input point is in the convex hull of the input vertices, in
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// which case the interpolation is valid.
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bool operator()(Vector3<Real> const& P, Real& F) const
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{
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int t = mMesh->GetContainingTetrahedron(P);
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if (t == -1)
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{
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// The point is outside the tetrahedralization.
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return false;
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}
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// Get the barycentric coordinates of P with respect to the tetrahedron,
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// P = b0*V0 + b1*V1 + b2*V2 + b3*V3, where b0 + b1 + b2 + b3 = 1.
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std::array<Real, 4> bary;
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if (!mMesh->GetBarycentrics(t, P, bary))
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{
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// TODO: Throw an exception or allow this as valid behavior?
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// P is in a needle-like, flat, or degenerate tetrahedron.
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return false;
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}
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// The result is a barycentric combination of function values.
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std::array<int, 4> indices;
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mMesh->GetIndices(t, indices);
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F = bary[0] * mF[indices[0]] + bary[1] * mF[indices[1]] +
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bary[2] * mF[indices[2]] + bary[3] * mF[indices[4]];
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return true;
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}
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private:
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TetrahedronMesh const* mMesh;
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Real const* mF;
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};
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}
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