Bullet Collision Detection & Physics Library
btContactProcessing.cpp
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1 
2 /*
3 This source file is part of GIMPACT Library.
4 
5 For the latest info, see http://gimpact.sourceforge.net/
6 
7 Copyright (c) 2007 Francisco Leon Najera. C.C. 80087371.
8 email: projectileman@yahoo.com
9 
10 
11 This software is provided 'as-is', without any express or implied warranty.
12 In no event will the authors be held liable for any damages arising from the use of this software.
13 Permission is granted to anyone to use this software for any purpose,
14 including commercial applications, and to alter it and redistribute it freely,
15 subject to the following restrictions:
16 
17 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
18 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
19 3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "btContactProcessing.h"
22 
23 #define MAX_COINCIDENT 8
24 
26 {
27  unsigned int m_key;
28  int m_value;
30  {
31  }
32 
33  CONTACT_KEY_TOKEN(unsigned int key, int token)
34  {
35  m_key = key;
36  m_value = token;
37  }
38 
40  {
41  m_key = rtoken.m_key;
42  m_value = rtoken.m_value;
43  }
44 
45  inline bool operator<(const CONTACT_KEY_TOKEN& other) const
46  {
47  return (m_key < other.m_key);
48  }
49 
50  inline bool operator>(const CONTACT_KEY_TOKEN& other) const
51  {
52  return (m_key > other.m_key);
53  }
54 };
55 
57 {
58 public:
59  bool operator()(const CONTACT_KEY_TOKEN& a, const CONTACT_KEY_TOKEN& b) const
60  {
61  return (a < b);
62  }
63 };
64 
66  const btContactArray& contacts, bool normal_contact_average)
67 {
68  clear();
69 
70  int i;
71  if (contacts.size() == 0) return;
72 
73  if (contacts.size() == 1)
74  {
75  push_back(contacts[0]);
76  return;
77  }
78 
80 
81  keycontacts.reserve(contacts.size());
82 
83  //fill key contacts
84 
85  for (i = 0; i < contacts.size(); i++)
86  {
87  keycontacts.push_back(CONTACT_KEY_TOKEN(contacts[i].calc_key_contact(), i));
88  }
89 
90  //sort keys
91  keycontacts.quickSort(CONTACT_KEY_TOKEN_COMP());
92 
93  // Merge contacts
94  int coincident_count = 0;
95  btVector3 coincident_normals[MAX_COINCIDENT];
96 
97  unsigned int last_key = keycontacts[0].m_key;
98  unsigned int key = 0;
99 
100  push_back(contacts[keycontacts[0].m_value]);
101 
102  GIM_CONTACT* pcontact = &(*this)[0];
103 
104  for (i = 1; i < keycontacts.size(); i++)
105  {
106  key = keycontacts[i].m_key;
107  const GIM_CONTACT* scontact = &contacts[keycontacts[i].m_value];
108 
109  if (last_key == key) //same points
110  {
111  //merge contact
112  if (pcontact->m_depth - CONTACT_DIFF_EPSILON > scontact->m_depth) //)
113  {
114  *pcontact = *scontact;
115  coincident_count = 0;
116  }
117  else if (normal_contact_average)
118  {
119  if (btFabs(pcontact->m_depth - scontact->m_depth) < CONTACT_DIFF_EPSILON)
120  {
121  if (coincident_count < MAX_COINCIDENT)
122  {
123  coincident_normals[coincident_count] = scontact->m_normal;
124  coincident_count++;
125  }
126  }
127  }
128  }
129  else
130  { //add new contact
131 
132  if (normal_contact_average && coincident_count > 0)
133  {
134  pcontact->interpolate_normals(coincident_normals, coincident_count);
135  coincident_count = 0;
136  }
137 
138  push_back(*scontact);
139  pcontact = &(*this)[this->size() - 1];
140  }
141  last_key = key;
142  }
143 }
144 
146 {
147  clear();
148 
149  if (contacts.size() == 0) return;
150 
151  if (contacts.size() == 1)
152  {
153  push_back(contacts[0]);
154  return;
155  }
156 
157  GIM_CONTACT average_contact = contacts[0];
158 
159  for (int i = 1; i < contacts.size(); i++)
160  {
161  average_contact.m_point += contacts[i].m_point;
162  average_contact.m_normal += contacts[i].m_normal * contacts[i].m_depth;
163  }
164 
165  //divide
166  btScalar divide_average = 1.0f / ((btScalar)contacts.size());
167 
168  average_contact.m_point *= divide_average;
169 
170  average_contact.m_normal *= divide_average;
171 
172  average_contact.m_depth = average_contact.m_normal.length();
173 
174  average_contact.m_normal /= average_contact.m_depth;
175 }
void interpolate_normals(btVector3 *normals, int normal_count)
void push_back(const GIM_CONTACT &_Val)
The btAlignedObjectArray template class uses a subset of the stl::vector interface for its methods It...
CONTACT_KEY_TOKEN(unsigned int key, int token)
bool operator()(const CONTACT_KEY_TOKEN &a, const CONTACT_KEY_TOKEN &b) const
#define CONTACT_DIFF_EPSILON
bool operator>(const CONTACT_KEY_TOKEN &other) const
void clear()
clear the array, deallocated memory. Generally it is better to use array.resize(0), to reduce performance overhead of run-time memory (de)allocations.
void merge_contacts(const btContactArray &contacts, bool normal_contact_average=true)
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
int size() const
return the number of elements in the array
bool operator<(const CONTACT_KEY_TOKEN &other) const
The GIM_CONTACT is an internal GIMPACT structure, similar to btManifoldPoint.
CONTACT_KEY_TOKEN(const CONTACT_KEY_TOKEN &rtoken)
void merge_contacts_unique(const btContactArray &contacts)
#define MAX_COINCIDENT
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:294
void quickSort(const L &CompareFunc)
btScalar length() const
Return the length of the vector.
Definition: btVector3.h:257
btScalar btFabs(btScalar x)
Definition: btScalar.h:477