Bullet Collision Detection & Physics Library
btDantzigLCP.h
Go to the documentation of this file.
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"
55 
57 {
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_
btAlignedObjectArray< btScalar * > Arows
Definition: btDantzigLCP.h:65
btAlignedObjectArray< btScalar > delta_w
Definition: btDantzigLCP.h:61
bool btSolveDantzigLCP(int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w, int nub, btScalar *lo, btScalar *hi, int *findex, btDantzigScratchMemory &scratch)
btAlignedObjectArray< btScalar > m_scratch
Definition: btDantzigLCP.h:58
btAlignedObjectArray< btScalar > Dell
Definition: btDantzigLCP.h:63
btAlignedObjectArray< int > p
Definition: btDantzigLCP.h:66
btAlignedObjectArray< int > C
Definition: btDantzigLCP.h:67
btAlignedObjectArray< btScalar > ell
Definition: btDantzigLCP.h:64
btAlignedObjectArray< btScalar > delta_x
Definition: btDantzigLCP.h:62
btAlignedObjectArray< btScalar > L
Definition: btDantzigLCP.h:59
btAlignedObjectArray< btScalar > d
Definition: btDantzigLCP.h:60
btAlignedObjectArray< bool > state
Definition: btDantzigLCP.h:68
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292