Bullet Collision Detection & Physics Library: btDantzigLCP.h Source File

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btDantzigLCP.h
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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
20given (A,b,lo,hi), solve the LCP problem: A*x = b+w, where each x(i),w(i)
21satisfies one of
22 (1) x = lo, w >= 0
23 (2) x = hi, w <= 0
24 (3) lo < x < hi, w = 0
25A is a matrix of dimension n*n, everything else is a vector of size n*1.
26lo and hi can be +/- dInfinity as needed. the first `nub' variables are
27unbounded, i.e. hi and lo are assumed to be +/- dInfinity.
28
29we restrict lo(i) <= 0 and hi(i) >= 0.
30
31the original data (A,b) may be modified by this function.
32
33if the `findex' (friction index) parameter is nonzero, it points to an array
34of index values. in this case constraints that have findex[i] >= 0 are
35special. all non-special constraints are solved for, then the lo and hi values
36for the special constraints are set:
37 hi[i] = abs( hi[i] * x[findex[i]] )
38 lo[i] = -hi[i]
39and the solution continues. this mechanism allows a friction approximation
40to be implemented. the first `nub' variables are assumed to have findex < 0.
41
42*/
43
44#ifndef _BT_LCP_H_
45#define _BT_LCP_H_
46
47#include <stdlib.h>
48#include <stdio.h>
49#include <assert.h>
50
51#include "LinearMath/btScalar.h"
52#include "LinearMath/btAlignedObjectArray.h"
53
54 struct btDantzigScratchMemory
55{
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;
67};
68
69//return false if solving failed
70bool btSolveDantzigLCP(int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w,
71 int nub, btScalar *lo, btScalar *hi, int *findex, btDantzigScratchMemory &scratch);
72
73#endif //_BT_LCP_H_
btAlignedObjectArray.h
btSolveDantzigLCP
bool btSolveDantzigLCP(int n, btScalar *A, btScalar *x, btScalar *b, btScalar *w, int nub, btScalar *lo, btScalar *hi, int *findex, btDantzigScratchMemory &scratch)
Definition: btDantzigLCP.cpp:1838
btScalar.h
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
btAlignedObjectArray
The btAlignedObjectArray template class uses a subset of the stl::vector interface for its methods It...
Definition: btAlignedObjectArray.h:46
btDantzigScratchMemory
Definition: btDantzigLCP.h:55
btDantzigScratchMemory::C
btAlignedObjectArray< int > C
Definition: btDantzigLCP.h:65
btDantzigScratchMemory::delta_w
btAlignedObjectArray< btScalar > delta_w
Definition: btDantzigLCP.h:59
btDantzigScratchMemory::delta_x
btAlignedObjectArray< btScalar > delta_x
Definition: btDantzigLCP.h:60
btDantzigScratchMemory::ell
btAlignedObjectArray< btScalar > ell
Definition: btDantzigLCP.h:62
btDantzigScratchMemory::Dell
btAlignedObjectArray< btScalar > Dell
Definition: btDantzigLCP.h:61
btDantzigScratchMemory::d
btAlignedObjectArray< btScalar > d
Definition: btDantzigLCP.h:58
btDantzigScratchMemory::L
btAlignedObjectArray< btScalar > L
Definition: btDantzigLCP.h:57
btDantzigScratchMemory::state
btAlignedObjectArray< bool > state
Definition: btDantzigLCP.h:66
btDantzigScratchMemory::m_scratch
btAlignedObjectArray< btScalar > m_scratch
Definition: btDantzigLCP.h:56
btDantzigScratchMemory::p
btAlignedObjectArray< int > p
Definition: btDantzigLCP.h:64
btDantzigScratchMemory::Arows
btAlignedObjectArray< btScalar * > Arows
Definition: btDantzigLCP.h:63