261 lines
9.4 KiB
C++
261 lines
9.4 KiB
C++
/*
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** Command & Conquer Renegade(tm)
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** Copyright 2025 Electronic Arts Inc.
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**
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** This program is free software: you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation, either version 3 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "col.h"
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// The eight box vertices of the box at time zero are
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// center+extent[i]*basis[i]
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// center-extent[i]*basis[i]
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// for i = 0,1,2,3. The vertices after a time step of dt are
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// center+dt*velocity+extent[i]*basis[i]
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// center+dt*velocity-extent[i]*basis[i]
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// for i = 0,1,2,3.
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//---------------------------------------------------------------------------
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IntersectType BoxesIntersect (float dt, const Box& box0, const Box& box1)
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{
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// Comments indicate where additional speed is gained for orthonormal bases
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// for both boxes. If a box is known to be flat (a[i] = 0 for some i OR
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// b[j] = 0 for some j), then more terms can be eliminated.
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const Vector* A = box0.basis;
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const Vector* B = box1.basis;
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const float* a = box0.extent;
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const float* b = box1.extent;
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// memoized values for Dot(A[i],A[j]), Dot(A[i],B[j]), Dot(B[i],B[j])
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float AA[3][3], AB[3][3], BB[3][3];
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// calculate difference of centers
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Vector C, V;
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Sub(box1.center,box0.center,C);
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Sub(box1.velocity,box0.velocity,V);
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float ra, rb, rsum, u0, u1;
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// L = A0
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AA[0][0] = Dot(A[0],A[0]); // = 1 for orthonormal basis
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AA[0][1] = Dot(A[0],A[1]); // = 0 for orthonormal basis
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AA[0][2] = Dot(A[0],A[2]); // = 0 for orthonormal basis
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AB[0][0] = Dot(A[0],B[0]);
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AB[0][1] = Dot(A[0],B[1]);
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AB[0][2] = Dot(A[0],B[2]);
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ra = FABS(a[0]*AA[0][0])+FABS(a[1]*AA[0][1])+FABS(a[2]*AA[0][2]);
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// = FABS(a[0]) for orthonormal basis
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rb = FABS(b[0]*AB[0][0])+FABS(b[1]*AB[0][1])+FABS(b[2]*AB[0][2]);
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rsum = ra+rb;
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u0 = Dot(C,A[0]);
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u1 = u0+dt*Dot(V,A[0]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA0;
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// L = A1
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AA[1][1] = Dot(A[1],A[1]); // = 1 for orthonormal basis
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AA[1][2] = Dot(A[1],A[2]); // = 0 for orthonormal basis
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AB[1][0] = Dot(A[1],B[0]);
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AB[1][1] = Dot(A[1],B[1]);
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AB[1][2] = Dot(A[1],B[2]);
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ra = FABS(a[0]*AA[0][1])+FABS(a[1]*AA[1][1])+FABS(a[2]*AA[1][2]);
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// = FABS(a[1]) for orthonormal basis
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rb = FABS(b[0]*AB[1][0])+FABS(b[1]*AB[1][1])+FABS(b[2]*AB[1][2]);
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rsum = ra+rb;
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u0 = Dot(C,A[1]);
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u1 = u0+dt*Dot(V,A[1]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA1;
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// L = A2
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AA[2][2] = Dot(A[2],A[2]); // = 1 for orthonormal basis
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AB[2][0] = Dot(A[2],B[0]);
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AB[2][1] = Dot(A[2],B[1]);
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AB[2][2] = Dot(A[2],B[2]);
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ra = FABS(a[0]*AA[0][2])+FABS(a[1]*AA[1][2])+FABS(a[2]*AA[2][2]);
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// = FABS(a[2]) for orthonormal basis
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rb = FABS(b[0]*AB[2][0])+FABS(b[1]*AB[2][1])+FABS(b[2]*AB[2][2]);
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rsum = ra+rb;
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u0 = Dot(C,A[2]);
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u1 = u0+dt*Dot(V,A[2]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA2;
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// L = B0
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BB[0][0] = Dot(B[0],B[0]); // = 1 for orthonormal basis
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BB[0][1] = Dot(B[0],B[1]); // = 0 for orthonormal basis
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BB[0][2] = Dot(B[0],B[2]); // = 0 for orthonormal basis
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ra = FABS(a[0]*AB[0][0])+FABS(a[1]*AB[1][0])+FABS(a[2]*AB[2][0]);
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rb = FABS(b[0]*BB[0][0])+FABS(b[1]*BB[0][1])+FABS(b[2]*BB[0][2]);
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// = FABS(b[0]) for orthonormal basis
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rsum = ra+rb;
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u0 = Dot(C,B[0]);
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u1 = u0+dt*Dot(V,B[0]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itB0;
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// L = B1
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BB[1][1] = Dot(B[1],B[1]); // = 1 for orthonormal basis
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BB[1][2] = Dot(B[1],B[2]); // = 0 for orthonormal basis
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ra = FABS(a[0]*AB[0][1])+FABS(a[1]*AB[1][1])+FABS(a[2]*AB[2][1]);
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rb = FABS(b[0]*BB[0][1])+FABS(b[1]*BB[1][1])+FABS(b[2]*BB[1][2]);
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// = FABS(b[1]) for orthonormal basis
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rsum = ra+rb;
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u0 = Dot(C,B[1]);
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u1 = u0+dt*Dot(V,B[1]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itB1;
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// L = B2
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BB[2][2] = Dot(B[2],B[2]); // = 1 for orthonormal basis
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ra = FABS(a[0]*AB[0][2])+FABS(a[1]*AB[1][2])+FABS(a[2]*AB[2][2]);
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rb = FABS(b[0]*BB[0][2])+FABS(b[1]*BB[1][2])+FABS(b[2]*BB[2][2]);
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// = FABS(b[2]) for orthonormal basis
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rsum = ra+rb;
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u0 = Dot(C,B[2]);
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u1 = u0+dt*Dot(V,B[2]);
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itB2;
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// check separating axes which are cross products of box edges
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float Ainv[3][3], coeff[3][3];
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Invert3x3(A,Ainv);
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// Ainv = Transpose(A) for orthonormal basis, no need to invert
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MultiplyMM(B,Ainv,coeff);
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// coeff[i][j] = AB[j][i] for orthonormal basis, no need to multiply
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// memoize minors of coefficient matrix
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float minor[3][3];
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// difference of centers in A-basis
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Vector d0, d1, product;
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MultiplyVM(C,Ainv,d0); // Ainv = Transpose(A) for orthonormal basis
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MultiplyVM(V,Ainv,d1); // Ainv = Transpose(A) for orthonormal basis
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ScalarMult(dt,d1,product);
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Add(d0,product,d1);
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// L = A0xB0
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minor[0][1] = coeff[0][1]*coeff[2][2]-coeff[2][1]*coeff[0][2];
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// = -coeff[1][0] for orthonormal bases
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minor[0][2] = coeff[0][1]*coeff[1][2]-coeff[1][1]*coeff[0][2];
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// = +coeff[2][0] for orthonormal bases
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ra = FABS(a[1]*coeff[0][2])+FABS(a[2]*coeff[0][1]);
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rb = FABS(b[1]*minor[0][2])+FABS(b[2]*minor[0][1]);
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// = FABS(b[1]*coeff[2][0])+FABS(b[2]*coeff[1][0]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[2]*coeff[1][0]-d0[1]*coeff[2][0];
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u1 = d1[2]*coeff[1][0]-d1[1]*coeff[2][0];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA0B0;
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// L = A0xB1
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minor[0][0] = coeff[1][1]*coeff[2][2]-coeff[2][1]*coeff[1][2];
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// = +coeff[0][0] for orthonormal bases
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ra = FABS(a[1]*coeff[1][2])+FABS(a[2]*coeff[1][1]);
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rb = FABS(b[0]*minor[0][2])+FABS(b[2]*minor[0][0]);
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// = FABS(b[0]*coeff[2][0])+FABS(b[2]*coeff[0][0]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[2]*coeff[1][1]-d0[1]*coeff[1][2];
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u1 = d1[2]*coeff[1][1]-d1[1]*coeff[1][2];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA0B1;
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// L = A0xB2
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ra = FABS(a[1]*coeff[2][2])+FABS(a[2]*coeff[2][1]);
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rb = FABS(b[0]*minor[0][1])+FABS(b[1]*minor[0][0]);
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// = FABS(b[0]*coeff[1][0])+FABS(b[1]*coeff[0][0]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[2]*coeff[2][1]-d0[1]*coeff[2][2];
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u1 = d1[2]*coeff[2][1]-d1[1]*coeff[2][2];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA0B2;
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// L = A1xB0
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minor[1][1] = coeff[0][0]*coeff[2][2]-coeff[2][0]*coeff[0][2];
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// = +coeff[1][1] for orthonormal bases
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minor[1][2] = coeff[0][0]*coeff[1][2]-coeff[1][0]*coeff[0][2];
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// = -coeff[2][1] for orthonormal bases
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ra = FABS(a[0]*coeff[0][2])+FABS(a[2]*coeff[0][0]);
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rb = FABS(b[1]*minor[1][2])+FABS(b[2]*minor[1][1]);
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// = FABS(b[1]*coeff[2][1])+FABS(b[2]*coeff[1][1]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[0]*coeff[0][2]-d0[2]*coeff[0][0];
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u1 = d1[0]*coeff[0][2]-d1[2]*coeff[0][0];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA1B0;
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// L = A1xB1
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minor[1][0] = coeff[1][0]*coeff[2][2]-coeff[2][0]*coeff[1][2];
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// = -coeff[0][1] for orthonormal bases
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ra = FABS(a[0]*coeff[1][2])+FABS(a[2]*coeff[1][0]);
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rb = FABS(b[0]*minor[1][2])+FABS(b[2]*minor[1][0]);
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// = FABS(b[0]*coeff[2][1])+FABS(b[2]*coeff[0][1]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[0]*coeff[1][2]-d0[2]*coeff[1][0];
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u1 = d1[0]*coeff[1][2]-d1[2]*coeff[1][0];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA1B1;
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// L = A1xB2
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ra = FABS(a[0]*coeff[2][2])+FABS(a[2]*coeff[2][0]);
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rb = FABS(b[0]*minor[1][1])+FABS(b[1]*minor[1][0]);
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// = FABS(b[0]*coeff[1][1])+FABS(b[1]*coeff[0][1]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[0]*coeff[2][2]-d0[2]*coeff[2][0];
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u1 = d1[0]*coeff[2][2]-d1[2]*coeff[2][0];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA1B2;
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// L = A2xB0
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minor[2][1] = coeff[0][0]*coeff[2][1]-coeff[2][0]*coeff[0][1];
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// = -coeff[2][1] for orthonormal bases
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minor[2][2] = coeff[0][0]*coeff[1][1]-coeff[1][0]*coeff[0][1];
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// = +coeff[2][2] for orthonormal bases
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ra = FABS(a[0]*coeff[0][1])+FABS(a[1]*coeff[0][0]);
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rb = FABS(b[1]*minor[2][2])+FABS(b[2]*minor[2][1]);
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// = FABS(b[1]*coeff[2][2])+FABS(b[2]*coeff[1][2]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[1]*coeff[0][0]-d0[0]*coeff[0][1];
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u1 = d1[1]*coeff[0][0]-d1[0]*coeff[0][1];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA2B0;
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// L = A2xB1
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minor[2][0] = coeff[1][0]*coeff[2][1]-coeff[2][0]*coeff[1][1];
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// = +coeff[0][2] for orthonormal bases
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ra = FABS(a[0]*coeff[1][1])+FABS(a[1]*coeff[1][0]);
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rb = FABS(b[0]*minor[2][2])+FABS(b[2]*minor[2][0]);
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// = FABS(b[0]*coeff[2][2])+FABS(b[2]*coeff[0][2]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[1]*coeff[1][0]-d0[0]*coeff[1][1];
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u1 = d1[1]*coeff[1][0]-d1[0]*coeff[1][1];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA2B1;
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// L = A2xB2
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ra = FABS(a[0]*coeff[2][1])+FABS(a[1]*coeff[2][0]);
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rb = FABS(b[0]*minor[2][1])+FABS(b[1]*minor[2][0]);
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// = FABS(b[0]*coeff[1][2])+FABS(b[1]*coeff[0][2]) for orthonormal bases
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rsum = ra+rb;
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u0 = d0[1]*coeff[2][0]-d0[0]*coeff[2][1];
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u1 = d1[1]*coeff[2][0]-d1[0]*coeff[2][1];
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if ((u0 > rsum && u1 > rsum) || (u0 < -rsum && u1 < -rsum) )
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return itA2B2;
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return itIntersects;
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}
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