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72 lines
2.4 KiB
72 lines
2.4 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/Vector2.h>
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// Linear interpolation of a network of triangles whose vertices are of the
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// form (x,y,f(x,y)). The function samples are F[i] and represent
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// f(x[i],y[i]), where i is the index of the input vertex (x[i],y[i]) to
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// Delaunay2.
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//
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// The TriangleMesh interface must support the following:
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// bool GetIndices(int, std::array<int, 3>&) const;
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// bool GetBarycentrics(int, Vector2<Real> const&,
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// std::array<Real, 3>&) const;
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// int GetContainingTriangle(Vector2<Real> const&) const;
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namespace gte
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{
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template <typename Real, typename TriangleMesh>
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class IntpLinearNonuniform2
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{
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public:
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// Construction.
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IntpLinearNonuniform2(TriangleMesh 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 P 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()(Vector2<Real> const& P, Real& F) const
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{
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int t = mMesh->GetContainingTriangle(P);
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if (t == -1)
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{
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// The point is outside the triangulation.
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return false;
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}
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// Get the barycentric coordinates of P with respect to the triangle,
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// P = b0*V0 + b1*V1 + b2*V2, where b0 + b1 + b2 = 1.
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std::array<Real, 3> 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 or degenerate triangle.
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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, 3> indices;
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mMesh->GetIndices(t, indices);
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F = bary[0] * mF[indices[0]] + bary[1] * mF[indices[1]] + bary[2] * mF[indices[2]];
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return true;
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}
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private:
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TriangleMesh const* mMesh;
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Real const* mF;
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};
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}
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