1 files changed, 371 insertions, 0 deletions
diff --git a/thirdparty/bullet/BulletDynamics/MLCPSolvers/btLemkeAlgorithm.cpp b/thirdparty/bullet/BulletDynamics/MLCPSolvers/btLemkeAlgorithm.cpp
new file mode 100644
index 0000000000..1f4015c7c7
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+++ b/thirdparty/bullet/BulletDynamics/MLCPSolvers/btLemkeAlgorithm.cpp
@@ -0,0 +1,371 @@
+/* Copyright (C) 2004-2013 MBSim Development Team
+
+Code was converted for the Bullet Continuous Collision Detection and Physics Library
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+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.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+//The original version is here
+//https://code.google.com/p/mbsim-env/source/browse/trunk/kernel/mbsim/numerics/linear_complementarity_problem/lemke_algorithm.cc
+//This file is re-distributed under the ZLib license, with permission of the original author
+//Math library was replaced from fmatvec to a the file src/LinearMath/btMatrixX.h
+//STL/std::vector replaced by btAlignedObjectArray
+
+
+
+#include "btLemkeAlgorithm.h"
+
+#undef BT_DEBUG_OSTREAM
+#ifdef BT_DEBUG_OSTREAM
+using namespace std;
+#endif //BT_DEBUG_OSTREAM
+
+btScalar btMachEps()
+{
+	static bool calculated=false;
+	static btScalar machEps = btScalar(1.);
+	if (!calculated)
+	{
+		do {
+			machEps /= btScalar(2.0);
+			// If next epsilon yields 1, then break, because current
+			// epsilon is the machine epsilon.
+		}
+		while ((btScalar)(1.0 + (machEps/btScalar(2.0))) != btScalar(1.0));
+//		printf( "\nCalculated Machine epsilon: %G\n", machEps );
+		calculated=true;
+	}
+	return machEps;
+}
+
+btScalar btEpsRoot() {
+	
+	static btScalar epsroot = 0.;
+	static bool alreadyCalculated = false;
+	
+	if (!alreadyCalculated) {
+		epsroot = btSqrt(btMachEps());
+		alreadyCalculated = true;
+	}
+	return epsroot;
+}
+
+	 
+
+  btVectorXu btLemkeAlgorithm::solve(unsigned int maxloops /* = 0*/)
+{
+  
+    
+    steps = 0;
+
+    int dim = m_q.size();
+#ifdef BT_DEBUG_OSTREAM
+    if(DEBUGLEVEL >= 1) {
+      cout << "Dimension = " << dim << endl;
+    }
+#endif //BT_DEBUG_OSTREAM
+
+	btVectorXu solutionVector(2 * dim);
+	solutionVector.setZero();
+	  
+	  //, INIT, 0.);
+
+	btMatrixXu ident(dim, dim);
+	ident.setIdentity();
+#ifdef BT_DEBUG_OSTREAM
+	cout << m_M << std::endl;
+#endif
+
+	btMatrixXu mNeg = m_M.negative();
+	  
+    btMatrixXu A(dim, 2 * dim + 2);
+	//
+	A.setSubMatrix(0, 0, dim - 1, dim - 1,ident);
+	A.setSubMatrix(0, dim, dim - 1, 2 * dim - 1,mNeg);
+	A.setSubMatrix(0, 2 * dim, dim - 1, 2 * dim, -1.f);
+	A.setSubMatrix(0, 2 * dim + 1, dim - 1, 2 * dim + 1,m_q);
+
+#ifdef BT_DEBUG_OSTREAM
+	cout << A << std::endl;
+#endif //BT_DEBUG_OSTREAM
+
+
+ //   btVectorXu q_;
+ //   q_ >> A(0, 2 * dim + 1, dim - 1, 2 * dim + 1);
+
+    btAlignedObjectArray<int> basis;
+    //At first, all w-values are in the basis
+    for (int i = 0; i < dim; i++)
+      basis.push_back(i);
+
+	int pivotRowIndex = -1;
+	btScalar minValue = 1e30f;
+	bool greaterZero = true;
+	for (int i=0;i<dim;i++)
+	{
+		btScalar v =A(i,2*dim+1);
+		if (v<minValue)
+		{
+			minValue=v;
+			pivotRowIndex = i;
+		}
+		if (v<0)
+			greaterZero = false;
+	}
+	
+
+	
+  //  int pivotRowIndex = q_.minIndex();//minIndex(q_);     // first row is that with lowest q-value
+    int z0Row = pivotRowIndex;           // remember the col of z0 for ending algorithm afterwards
+    int pivotColIndex = 2 * dim;         // first col is that of z0
+
+#ifdef BT_DEBUG_OSTREAM
+    if (DEBUGLEVEL >= 3)
+	{
+    //  cout << "A: " << A << endl;
+      cout << "pivotRowIndex " << pivotRowIndex << endl;
+      cout << "pivotColIndex " << pivotColIndex << endl;
+      cout << "Basis: ";
+      for (int i = 0; i < basis.size(); i++)
+        cout << basis[i] << " ";
+      cout << endl;
+    }
+#endif //BT_DEBUG_OSTREAM
+
+	if (!greaterZero)
+	{
+
+      if (maxloops == 0) {
+		  maxloops = 100;
+//        maxloops = UINT_MAX; //TODO: not a really nice way, problem is: maxloops should be 2^dim (=1<<dim), but this could exceed UINT_MAX and thus the result would be 0 and therefore the lemke algorithm wouldn't start but probably would find a solution within less then UINT_MAX steps. Therefore this constant is used as a upper border right now...
+      }
+
+      /*start looping*/
+      for(steps = 0; steps < maxloops; steps++) {
+
+        GaussJordanEliminationStep(A, pivotRowIndex, pivotColIndex, basis);
+#ifdef BT_DEBUG_OSTREAM
+        if (DEBUGLEVEL >= 3) {
+        //  cout << "A: " << A << endl;
+          cout << "pivotRowIndex " << pivotRowIndex << endl;
+          cout << "pivotColIndex " << pivotColIndex << endl;
+          cout << "Basis: ";
+          for (int i = 0; i < basis.size(); i++)
+            cout << basis[i] << " ";
+          cout << endl;
+        }
+#endif //BT_DEBUG_OSTREAM
+
+        int pivotColIndexOld = pivotColIndex;
+
+        /*find new column index */
+        if (basis[pivotRowIndex] < dim) //if a w-value left the basis get in the correspondent z-value
+          pivotColIndex = basis[pivotRowIndex] + dim;
+        else
+          //else do it the other way round and get in the corresponding w-value
+          pivotColIndex = basis[pivotRowIndex] - dim;
+
+        /*the column becomes part of the basis*/
+        basis[pivotRowIndex] = pivotColIndexOld;
+
+        pivotRowIndex = findLexicographicMinimum(A, pivotColIndex);
+
+        if(z0Row == pivotRowIndex) { //if z0 leaves the basis the solution is found --> one last elimination step is necessary
+          GaussJordanEliminationStep(A, pivotRowIndex, pivotColIndex, basis);
+          basis[pivotRowIndex] = pivotColIndex; //update basis
+          break;
+      }
+
+      }
+#ifdef BT_DEBUG_OSTREAM
+      if(DEBUGLEVEL >= 1) {
+        cout << "Number of loops: " << steps << endl;
+        cout << "Number of maximal loops: " << maxloops << endl;
+      }
+#endif //BT_DEBUG_OSTREAM
+
+      if(!validBasis(basis)) {
+        info = -1;
+#ifdef BT_DEBUG_OSTREAM
+        if(DEBUGLEVEL >= 1)
+          cerr << "Lemke-Algorithm ended with Ray-Termination (no valid solution)." << endl;
+#endif //BT_DEBUG_OSTREAM
+
+        return solutionVector;
+      }
+
+    }
+#ifdef BT_DEBUG_OSTREAM
+    if (DEBUGLEVEL >= 2) {
+     // cout << "A: " << A << endl;
+      cout << "pivotRowIndex " << pivotRowIndex << endl;
+      cout << "pivotColIndex " << pivotColIndex << endl;
+    }
+#endif //BT_DEBUG_OSTREAM
+
+    for (int i = 0; i < basis.size(); i++)
+	{
+      solutionVector[basis[i]] = A(i,2*dim+1);//q_[i];
+	}
+
+    info = 0;
+
+    return solutionVector;
+  }
+
+  int btLemkeAlgorithm::findLexicographicMinimum(const btMatrixXu& A, const int & pivotColIndex) {
+	  int RowIndex = 0;
+	  int dim = A.rows();
+	  btAlignedObjectArray<btVectorXu> Rows;
+	  for (int row = 0; row < dim; row++) 
+	  {
+
+		  btVectorXu vec(dim + 1);
+		  vec.setZero();//, INIT, 0.)
+		  Rows.push_back(vec);
+		  btScalar a = A(row, pivotColIndex);
+		  if (a > 0) {
+			  Rows[row][0] = A(row, 2 * dim + 1) / a;
+			  Rows[row][1] = A(row, 2 * dim) / a;
+			  for (int j = 2; j < dim + 1; j++)
+				  Rows[row][j] = A(row, j - 1) / a;
+
+#ifdef BT_DEBUG_OSTREAM
+		//		if (DEBUGLEVEL) {
+			//	  cout << "Rows(" << row << ") = " << Rows[row] << endl;
+				// }
+#endif 
+		  }
+	  }
+
+	  for (int i = 0; i < Rows.size(); i++) 
+	  {
+		  if (Rows[i].nrm2() > 0.) {
+
+			  int j = 0;
+			  for (; j < Rows.size(); j++) 
+			  {
+				  if(i != j)
+				  {
+					  if(Rows[j].nrm2() > 0.)
+					  {
+						  btVectorXu test(dim + 1);
+						  for (int ii=0;ii<dim+1;ii++)
+						  {
+							  test[ii] = Rows[j][ii] - Rows[i][ii];
+						  }
+
+						  //=Rows[j] - Rows[i]
+						  if (! LexicographicPositive(test))
+							  break;
+					  }
+				  }
+			  }
+
+			  if (j == Rows.size()) 
+			  {
+				  RowIndex += i;
+				  break;
+			  }
+		  }
+	  }
+
+	  return RowIndex;
+  }
+
+  bool btLemkeAlgorithm::LexicographicPositive(const btVectorXu & v)
+{
+    int i = 0;
+  //  if (DEBUGLEVEL)
+    //  cout << "v " << v << endl;
+
+    while(i < v.size()-1 && fabs(v[i]) < btMachEps())
+      i++;
+    if (v[i] > 0)
+      return true;
+
+    return false;
+  }
+
+void btLemkeAlgorithm::GaussJordanEliminationStep(btMatrixXu& A, int pivotRowIndex, int pivotColumnIndex, const btAlignedObjectArray<int>& basis) 
+{
+
+	btScalar a = -1 / A(pivotRowIndex, pivotColumnIndex);
+#ifdef BT_DEBUG_OSTREAM
+	cout << A << std::endl;
+#endif
+
+    for (int i = 0; i < A.rows(); i++)
+	{
+      if (i != pivotRowIndex)
+	  {
+        for (int j = 0; j < A.cols(); j++)
+		{
+          if (j != pivotColumnIndex)
+		  {
+			  btScalar v = A(i, j);
+			  v += A(pivotRowIndex, j) * A(i, pivotColumnIndex) * a;
+            A.setElem(i, j, v);
+		  }
+		}
+	  }
+	}
+
+#ifdef BT_DEBUG_OSTREAM
+	cout << A << std::endl;
+#endif //BT_DEBUG_OSTREAM
+    for (int i = 0; i < A.cols(); i++) 
+	{
+      A.mulElem(pivotRowIndex, i,-a);
+    }
+#ifdef BT_DEBUG_OSTREAM
+	cout << A << std::endl;
+#endif //#ifdef BT_DEBUG_OSTREAM
+
+    for (int i = 0; i < A.rows(); i++)
+	{
+      if (i != pivotRowIndex)
+	  {
+        A.setElem(i, pivotColumnIndex,0);
+	  }
+	}
+#ifdef BT_DEBUG_OSTREAM
+	cout << A << std::endl;
+#endif //#ifdef BT_DEBUG_OSTREAM
+  }
+
+  bool btLemkeAlgorithm::greaterZero(const btVectorXu & vector)
+{
+    bool isGreater = true;
+    for (int i = 0; i < vector.size(); i++) {
+      if (vector[i] < 0) {
+        isGreater = false;
+        break;
+      }
+    }
+
+    return isGreater;
+  }
+
+  bool btLemkeAlgorithm::validBasis(const btAlignedObjectArray<int>& basis) 
+  {
+    bool isValid = true;
+    for (int i = 0; i < basis.size(); i++) {
+      if (basis[i] >= basis.size() * 2) { //then z0 is in the base
+        isValid = false;
+        break;
+      }
+    }
+
+    return isValid;
+  }
+
+