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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