1 /*************************************************************************
3 * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith. *
4 * All rights reserved. Email: russ@q12.org Web: www.q12.org *
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. *
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. *
16 *************************************************************************/
20 given (A,b,lo,hi), solve the LCP problem: A*x = b+w, where each x(i),w(i)
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.
29 we restrict lo(i) <= 0 and hi(i) >= 0.
31 the original data (A,b) may be modified by this function.
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]] )
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.
51 #include "LinearMath/btScalar.h"
52 #include "LinearMath/btAlignedObjectArray.h"
54 struct btDantzigScratchMemory
56 btAlignedObjectArray<btScalar> m_scratch;
57 btAlignedObjectArray<btScalar> L;
58 btAlignedObjectArray<btScalar> d;
59 btAlignedObjectArray<btScalar> delta_w;
60 btAlignedObjectArray<btScalar> delta_x;
61 btAlignedObjectArray<btScalar> Dell;
62 btAlignedObjectArray<btScalar> ell;
63 btAlignedObjectArray<btScalar *> Arows;
64 btAlignedObjectArray<int> p;
65 btAlignedObjectArray<int> C;
66 btAlignedObjectArray<bool> state;
69 //return false if solving failed
70 bool btSolveDantzigLCP(int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w,
71 int nub, btScalar *lo, btScalar *hi, int *findex, btDantzigScratchMemory &scratch);