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325 lines
12 KiB
325 lines
12 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/TIQuery.h>
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#include <Mathematics/OrientedBox.h>
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#include <Mathematics/Vector3.h>
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// The queries consider the box to be a solid.
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//
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// The test-intersection query uses the method of separating axes.
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// https://www.geometrictools.com/Documentation/MethodOfSeparatingAxes.pdf
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// The set of potential separating directions includes the 3 face normals of
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// box0, the 3 face normals of box1, and 9 directions, each of which is the
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// cross product of an edge of box0 and and an edge of box1.
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//
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// The separating axes involving cross products of edges has numerical
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// robustness problems when the two edges are nearly parallel. The cross
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// product of the edges is nearly the zero vector, so normalization of the
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// cross product may produce unit-length directions that are not close to the
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// true direction. Such a pair of edges occurs when a box0 face normal N0 and
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// a box1 face normal N1 are nearly parallel. In this case, you may skip the
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// edge-edge directions, which is equivalent to projecting the boxes onto the
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// plane with normal N0 and applying a 2D separating axis test. The ability
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// to do so involves choosing a small nonnegative epsilon. It is used to
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// determine whether two face normals, one from each box, are nearly parallel:
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// |Dot(N0,N1)| >= 1 - epsilon. If the input is negative, it is clamped to
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// zero.
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//
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// The pair of integers 'separating', say, (i0,i1), identify the axis that
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// reported separation; there may be more than one but only one is
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// reported. If the separating axis is a face normal N[i0] of the aligned
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// box0 in dimension i0, then (i0,-1) is returned. If the axis is a face
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// normal box1.Axis[i1], then (-1,i1) is returned. If the axis is a cross
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// product of edges, Cross(N[i0],box1.Axis[i1]), then (i0,i1) is returned.
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namespace gte
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{
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template <typename Real>
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class TIQuery<Real, OrientedBox3<Real>, OrientedBox3<Real>>
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{
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public:
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struct Result
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{
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// The 'epsilon' value must be nonnegative.
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Result(Real inEpsilon = (Real)0)
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:
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epsilon(inEpsilon >= (Real)0 ? inEpsilon : (Real)0)
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{
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}
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bool intersect;
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Real epsilon;
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int separating[2];
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};
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Result operator()(OrientedBox3<Real> const& box0, OrientedBox3<Real> const& box1)
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{
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Result result;
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// Convenience variables.
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Vector3<Real> const& C0 = box0.center;
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Vector3<Real> const* A0 = &box0.axis[0];
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Vector3<Real> const& E0 = box0.extent;
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Vector3<Real> const& C1 = box1.center;
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Vector3<Real> const* A1 = &box1.axis[0];
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Vector3<Real> const& E1 = box1.extent;
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Real const cutoff = (Real)1 - result.epsilon;
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bool existsParallelPair = false;
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// Compute difference of box centers.
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Vector3<Real> D = C1 - C0;
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// dot01[i][j] = Dot(A0[i],A1[j]) = A1[j][i]
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Real dot01[3][3];
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// |dot01[i][j]|
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Real absDot01[3][3];
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// Dot(D, A0[i])
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Real dotDA0[3];
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// interval radii and distance between centers
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Real r0, r1, r;
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// r0 + r1
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Real r01;
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// Test for separation on the axis C0 + t*A0[0].
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for (int i = 0; i < 3; ++i)
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{
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dot01[0][i] = Dot(A0[0], A1[i]);
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absDot01[0][i] = std::fabs(dot01[0][i]);
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if (absDot01[0][i] > cutoff)
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{
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existsParallelPair = true;
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}
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}
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dotDA0[0] = Dot(D, A0[0]);
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r = std::fabs(dotDA0[0]);
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r1 = E1[0] * absDot01[0][0] + E1[1] * absDot01[0][1] + E1[2] * absDot01[0][2];
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r01 = E0[0] + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 0;
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result.separating[1] = -1;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[1].
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for (int i = 0; i < 3; ++i)
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{
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dot01[1][i] = Dot(A0[1], A1[i]);
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absDot01[1][i] = std::fabs(dot01[1][i]);
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if (absDot01[1][i] > cutoff)
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{
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existsParallelPair = true;
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}
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}
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dotDA0[1] = Dot(D, A0[1]);
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r = std::fabs(dotDA0[1]);
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r1 = E1[0] * absDot01[1][0] + E1[1] * absDot01[1][1] + E1[2] * absDot01[1][2];
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r01 = E0[1] + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 1;
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result.separating[1] = -1;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[2].
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for (int i = 0; i < 3; ++i)
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{
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dot01[2][i] = Dot(A0[2], A1[i]);
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absDot01[2][i] = std::fabs(dot01[2][i]);
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if (absDot01[2][i] > cutoff)
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{
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existsParallelPair = true;
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}
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}
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dotDA0[2] = Dot(D, A0[2]);
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r = std::fabs(dotDA0[2]);
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r1 = E1[0] * absDot01[2][0] + E1[1] * absDot01[2][1] + E1[2] * absDot01[2][2];
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r01 = E0[2] + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 2;
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result.separating[1] = -1;
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return result;
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}
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// Test for separation on the axis C0 + t*A1[0].
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r = std::fabs(Dot(D, A1[0]));
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r0 = E0[0] * absDot01[0][0] + E0[1] * absDot01[1][0] + E0[2] * absDot01[2][0];
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r01 = r0 + E1[0];
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = -1;
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result.separating[1] = 0;
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return result;
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}
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// Test for separation on the axis C0 + t*A1[1].
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r = std::fabs(Dot(D, A1[1]));
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r0 = E0[0] * absDot01[0][1] + E0[1] * absDot01[1][1] + E0[2] * absDot01[2][1];
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r01 = r0 + E1[1];
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = -1;
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result.separating[1] = 1;
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return result;
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}
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// Test for separation on the axis C0 + t*A1[2].
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r = std::fabs(Dot(D, A1[2]));
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r0 = E0[0] * absDot01[0][2] + E0[1] * absDot01[1][2] + E0[2] * absDot01[2][2];
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r01 = r0 + E1[2];
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = -1;
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result.separating[1] = 2;
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return result;
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}
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// At least one pair of box axes was parallel, so the separation is
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// effectively in 2D. The edge-edge axes do not need to be tested.
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if (existsParallelPair)
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{
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return true;
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}
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// Test for separation on the axis C0 + t*A0[0]xA1[0].
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r = std::fabs(dotDA0[2] * dot01[1][0] - dotDA0[1] * dot01[2][0]);
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r0 = E0[1] * absDot01[2][0] + E0[2] * absDot01[1][0];
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r1 = E1[1] * absDot01[0][2] + E1[2] * absDot01[0][1];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 0;
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result.separating[1] = 0;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[0]xA1[1].
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r = std::fabs(dotDA0[2] * dot01[1][1] - dotDA0[1] * dot01[2][1]);
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r0 = E0[1] * absDot01[2][1] + E0[2] * absDot01[1][1];
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r1 = E1[0] * absDot01[0][2] + E1[2] * absDot01[0][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 0;
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result.separating[1] = 1;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[0]xA1[2].
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r = std::fabs(dotDA0[2] * dot01[1][2] - dotDA0[1] * dot01[2][2]);
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r0 = E0[1] * absDot01[2][2] + E0[2] * absDot01[1][2];
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r1 = E1[0] * absDot01[0][1] + E1[1] * absDot01[0][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 0;
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result.separating[1] = 2;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[1]xA1[0].
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r = std::fabs(dotDA0[0] * dot01[2][0] - dotDA0[2] * dot01[0][0]);
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r0 = E0[0] * absDot01[2][0] + E0[2] * absDot01[0][0];
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r1 = E1[1] * absDot01[1][2] + E1[2] * absDot01[1][1];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 1;
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result.separating[1] = 0;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[1]xA1[1].
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r = std::fabs(dotDA0[0] * dot01[2][1] - dotDA0[2] * dot01[0][1]);
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r0 = E0[0] * absDot01[2][1] + E0[2] * absDot01[0][1];
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r1 = E1[0] * absDot01[1][2] + E1[2] * absDot01[1][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 1;
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result.separating[1] = 1;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[1]xA1[2].
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r = std::fabs(dotDA0[0] * dot01[2][2] - dotDA0[2] * dot01[0][2]);
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r0 = E0[0] * absDot01[2][2] + E0[2] * absDot01[0][2];
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r1 = E1[0] * absDot01[1][1] + E1[1] * absDot01[1][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 1;
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result.separating[1] = 2;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[2]xA1[0].
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r = std::fabs(dotDA0[1] * dot01[0][0] - dotDA0[0] * dot01[1][0]);
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r0 = E0[0] * absDot01[1][0] + E0[1] * absDot01[0][0];
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r1 = E1[1] * absDot01[2][2] + E1[2] * absDot01[2][1];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 2;
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result.separating[1] = 0;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[2]xA1[1].
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r = std::fabs(dotDA0[1] * dot01[0][1] - dotDA0[0] * dot01[1][1]);
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r0 = E0[0] * absDot01[1][1] + E0[1] * absDot01[0][1];
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r1 = E1[0] * absDot01[2][2] + E1[2] * absDot01[2][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 2;
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result.separating[1] = 1;
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return result;
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}
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// Test for separation on the axis C0 + t*A0[2]xA1[2].
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r = std::fabs(dotDA0[1] * dot01[0][2] - dotDA0[0] * dot01[1][2]);
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r0 = E0[0] * absDot01[1][2] + E0[1] * absDot01[0][2];
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r1 = E1[0] * absDot01[2][1] + E1[1] * absDot01[2][0];
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r01 = r0 + r1;
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if (r > r01)
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{
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result.intersect = false;
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result.separating[0] = 2;
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result.separating[1] = 2;
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return result;
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}
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result.intersect = true;
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return result;
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}
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};
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}
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