1 /************************************************************************* 2 * * 3 * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith. * 4 * All rights reserved. Email: russ@q12.org Web: www.q12.org * 5 * * 6 * This library is free software; you can redistribute it and/or * 7 * modify it under the terms of * 8 * The BSD-style license that is included with this library in * 9 * the file LICENSE-BSD.TXT. * 10 * * 11 * This library is distributed in the hope that it will be useful, * 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of * 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files * 14 * LICENSE.TXT and LICENSE-BSD.TXT for more details. * 15 * * 16 *************************************************************************/ 17 18 /* 19 20 given (A,b,lo,hi), solve the LCP problem: A*x = b+w, where each x(i),w(i) 21 satisfies one of 22 (1) x = lo, w >= 0 23 (2) x = hi, w <= 0 24 (3) lo < x < hi, w = 0 25 A is a matrix of dimension n*n, everything else is a vector of size n*1. 26 lo and hi can be +/- dInfinity as needed. the first `nub' variables are 27 unbounded, i.e. hi and lo are assumed to be +/- dInfinity. 28 29 we restrict lo(i) <= 0 and hi(i) >= 0. 30 31 the original data (A,b) may be modified by this function. 32 33 if the `findex' (friction index) parameter is nonzero, it points to an array 34 of index values. in this case constraints that have findex[i] >= 0 are 35 special. all non-special constraints are solved for, then the lo and hi values 36 for the special constraints are set: 37 hi[i] = abs( hi[i] * x[findex[i]] ) 38 lo[i] = -hi[i] 39 and the solution continues. this mechanism allows a friction approximation 40 to be implemented. the first `nub' variables are assumed to have findex < 0. 41 42 */ 43 44 45 #ifndef _BT_LCP_H_ 46 #define _BT_LCP_H_ 47 48 #include <stdlib.h> 49 #include <stdio.h> 50 #include <assert.h> 51 52 53 #include "LinearMath/btScalar.h" 54 #include "LinearMath/btAlignedObjectArray.h" 55 56 struct btDantzigScratchMemory 57 { 58 btAlignedObjectArray<btScalar> m_scratch; 59 btAlignedObjectArray<btScalar> L; 60 btAlignedObjectArray<btScalar> d; 61 btAlignedObjectArray<btScalar> delta_w; 62 btAlignedObjectArray<btScalar> delta_x; 63 btAlignedObjectArray<btScalar> Dell; 64 btAlignedObjectArray<btScalar> ell; 65 btAlignedObjectArray<btScalar*> Arows; 66 btAlignedObjectArray<int> p; 67 btAlignedObjectArray<int> C; 68 btAlignedObjectArray<bool> state; 69 }; 70 71 //return false if solving failed 72 bool btSolveDantzigLCP (int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w, 73 int nub, btScalar *lo, btScalar *hi, int *findex,btDantzigScratchMemory& scratch); 74 75 76 77 #endif //_BT_LCP_H_ 78