339 lines
7.9 KiB
C++
339 lines
7.9 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2013 Erwin Coumans http://bulletphysics.org
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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///original version written by Erwin Coumans, October 2013
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#ifndef BT_LEMKE_SOLVER_H
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#define BT_LEMKE_SOLVER_H
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#include "btMLCPSolverInterface.h"
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#include "btLemkeAlgorithm.h"
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///The btLemkeSolver is based on "Fast Implementation of Lemke’s Algorithm for Rigid Body Contact Simulation (John E. Lloyd) "
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///It is a slower but more accurate solver. Increase the m_maxLoops for better convergence, at the cost of more CPU time.
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///The original implementation of the btLemkeAlgorithm was done by Kilian Grundl from the MBSim team
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class btLemkeSolver : public btMLCPSolverInterface
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{
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protected:
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public:
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btScalar m_maxValue;
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int m_debugLevel;
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int m_maxLoops;
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bool m_useLoHighBounds;
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btLemkeSolver()
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: m_maxValue(100000),
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m_debugLevel(0),
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m_maxLoops(1000),
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m_useLoHighBounds(true)
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{
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}
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virtual bool solveMLCP(const btMatrixXu& A, const btVectorXu& b, btVectorXu& x, const btVectorXu& lo, const btVectorXu& hi, const btAlignedObjectArray<int>& limitDependency, int numIterations, bool useSparsity = true)
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{
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if (m_useLoHighBounds)
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{
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BT_PROFILE("btLemkeSolver::solveMLCP");
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int n = A.rows();
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if (0 == n)
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return true;
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bool fail = false;
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btVectorXu solution(n);
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btVectorXu q1;
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q1.resize(n);
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for (int row = 0; row < n; row++)
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{
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q1[row] = -b[row];
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}
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// cout << "A" << endl;
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// cout << A << endl;
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/////////////////////////////////////
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//slow matrix inversion, replace with LU decomposition
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btMatrixXu A1;
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btMatrixXu B(n, n);
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{
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//BT_PROFILE("inverse(slow)");
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A1.resize(A.rows(), A.cols());
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for (int row = 0; row < A.rows(); row++)
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{
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for (int col = 0; col < A.cols(); col++)
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{
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A1.setElem(row, col, A(row, col));
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}
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}
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btMatrixXu matrix;
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matrix.resize(n, 2 * n);
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for (int row = 0; row < n; row++)
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{
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for (int col = 0; col < n; col++)
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{
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matrix.setElem(row, col, A1(row, col));
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}
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}
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btScalar ratio, a;
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int i, j, k;
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for (i = 0; i < n; i++)
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{
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for (j = n; j < 2 * n; j++)
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{
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if (i == (j - n))
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matrix.setElem(i, j, 1.0);
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else
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matrix.setElem(i, j, 0.0);
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}
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}
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for (i = 0; i < n; i++)
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{
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for (j = 0; j < n; j++)
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{
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if (i != j)
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{
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btScalar v = matrix(i, i);
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if (btFuzzyZero(v))
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{
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a = 0.000001f;
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}
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ratio = matrix(j, i) / matrix(i, i);
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for (k = 0; k < 2 * n; k++)
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{
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matrix.addElem(j, k, -ratio * matrix(i, k));
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}
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}
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}
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}
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for (i = 0; i < n; i++)
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{
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a = matrix(i, i);
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if (btFuzzyZero(a))
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{
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a = 0.000001f;
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}
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btScalar invA = 1.f / a;
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for (j = 0; j < 2 * n; j++)
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{
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matrix.mulElem(i, j, invA);
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}
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}
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for (int row = 0; row < n; row++)
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{
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for (int col = 0; col < n; col++)
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{
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B.setElem(row, col, matrix(row, n + col));
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}
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}
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}
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btMatrixXu b1(n, 1);
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btMatrixXu M(n * 2, n * 2);
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for (int row = 0; row < n; row++)
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{
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b1.setElem(row, 0, -b[row]);
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for (int col = 0; col < n; col++)
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{
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btScalar v = B(row, col);
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M.setElem(row, col, v);
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M.setElem(n + row, n + col, v);
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M.setElem(n + row, col, -v);
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M.setElem(row, n + col, -v);
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}
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}
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btMatrixXu Bb1 = B * b1;
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// q = [ (-B*b1 - lo)' (hi + B*b1)' ]'
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btVectorXu qq;
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qq.resize(n * 2);
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for (int row = 0; row < n; row++)
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{
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qq[row] = -Bb1(row, 0) - lo[row];
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qq[n + row] = Bb1(row, 0) + hi[row];
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}
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btVectorXu z1;
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btMatrixXu y1;
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y1.resize(n, 1);
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btLemkeAlgorithm lemke(M, qq, m_debugLevel);
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{
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//BT_PROFILE("lemke.solve");
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lemke.setSystem(M, qq);
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z1 = lemke.solve(m_maxLoops);
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}
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for (int row = 0; row < n; row++)
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{
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y1.setElem(row, 0, z1[2 * n + row] - z1[3 * n + row]);
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}
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btMatrixXu y1_b1(n, 1);
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for (int i = 0; i < n; i++)
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{
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y1_b1.setElem(i, 0, y1(i, 0) - b1(i, 0));
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}
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btMatrixXu x1;
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x1 = B * (y1_b1);
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for (int row = 0; row < n; row++)
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{
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solution[row] = x1(row, 0); //n];
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}
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int errorIndexMax = -1;
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int errorIndexMin = -1;
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float errorValueMax = -1e30;
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float errorValueMin = 1e30;
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for (int i = 0; i < n; i++)
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{
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x[i] = solution[i];
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volatile btScalar check = x[i];
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if (x[i] != check)
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{
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//printf("Lemke result is #NAN\n");
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x.setZero();
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return false;
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}
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//this is some hack/safety mechanism, to discard invalid solutions from the Lemke solver
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//we need to figure out why it happens, and fix it, or detect it properly)
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if (x[i] > m_maxValue)
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{
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if (x[i] > errorValueMax)
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{
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fail = true;
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errorIndexMax = i;
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errorValueMax = x[i];
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}
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////printf("x[i] = %f,",x[i]);
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}
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if (x[i] < -m_maxValue)
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{
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if (x[i] < errorValueMin)
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{
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errorIndexMin = i;
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errorValueMin = x[i];
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fail = true;
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//printf("x[i] = %f,",x[i]);
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}
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}
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}
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if (fail)
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{
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int m_errorCountTimes = 0;
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if (errorIndexMin < 0)
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errorValueMin = 0.f;
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if (errorIndexMax < 0)
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errorValueMax = 0.f;
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m_errorCountTimes++;
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// printf("Error (x[%d] = %f, x[%d] = %f), resetting %d times\n", errorIndexMin,errorValueMin, errorIndexMax, errorValueMax, errorCountTimes++);
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for (int i = 0; i < n; i++)
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{
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x[i] = 0.f;
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}
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}
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return !fail;
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}
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else
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{
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int dimension = A.rows();
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if (0 == dimension)
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return true;
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// printf("================ solving using Lemke/Newton/Fixpoint\n");
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btVectorXu q;
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q.resize(dimension);
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for (int row = 0; row < dimension; row++)
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{
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q[row] = -b[row];
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}
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btLemkeAlgorithm lemke(A, q, m_debugLevel);
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lemke.setSystem(A, q);
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btVectorXu solution = lemke.solve(m_maxLoops);
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//check solution
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bool fail = false;
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int errorIndexMax = -1;
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int errorIndexMin = -1;
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float errorValueMax = -1e30;
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float errorValueMin = 1e30;
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for (int i = 0; i < dimension; i++)
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{
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x[i] = solution[i + dimension];
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volatile btScalar check = x[i];
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if (x[i] != check)
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{
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x.setZero();
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return false;
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}
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//this is some hack/safety mechanism, to discard invalid solutions from the Lemke solver
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//we need to figure out why it happens, and fix it, or detect it properly)
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if (x[i] > m_maxValue)
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{
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if (x[i] > errorValueMax)
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{
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fail = true;
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errorIndexMax = i;
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errorValueMax = x[i];
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}
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////printf("x[i] = %f,",x[i]);
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}
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if (x[i] < -m_maxValue)
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{
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if (x[i] < errorValueMin)
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{
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errorIndexMin = i;
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errorValueMin = x[i];
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fail = true;
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//printf("x[i] = %f,",x[i]);
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}
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}
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}
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if (fail)
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{
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static int errorCountTimes = 0;
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if (errorIndexMin < 0)
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errorValueMin = 0.f;
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if (errorIndexMax < 0)
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errorValueMax = 0.f;
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printf("Error (x[%d] = %f, x[%d] = %f), resetting %d times\n", errorIndexMin, errorValueMin, errorIndexMax, errorValueMax, errorCountTimes++);
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for (int i = 0; i < dimension; i++)
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{
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x[i] = 0.f;
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}
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}
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return !fail;
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}
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return true;
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}
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};
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#endif //BT_LEMKE_SOLVER_H
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