351 lines
7.4 KiB
C
351 lines
7.4 KiB
C
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/*
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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<6B>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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for(j = n; j < 2*n; j++){
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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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for(j = 0; j < n; j++){
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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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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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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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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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} 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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