Bullet Collision Detection & Physics Library
gim_contact.cpp
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1 
2 /*
3 -----------------------------------------------------------------------------
4 This source file is part of GIMPACT Library.
5 
6 For the latest info, see http://gimpact.sourceforge.net/
7 
8 Copyright (c) 2006 Francisco Leon Najera. C.C. 80087371.
9 email: projectileman@yahoo.com
10 
11  This library is free software; you can redistribute it and/or
12  modify it under the terms of EITHER:
13  (1) The GNU Lesser General Public License as published by the Free
14  Software Foundation; either version 2.1 of the License, or (at
15  your option) any later version. The text of the GNU Lesser
16  General Public License is included with this library in the
17  file GIMPACT-LICENSE-LGPL.TXT.
18  (2) The BSD-style license that is included with this library in
19  the file GIMPACT-LICENSE-BSD.TXT.
20  (3) The zlib/libpng license that is included with this library in
21  the file GIMPACT-LICENSE-ZLIB.TXT.
22 
23  This library is distributed in the hope that it will be useful,
24  but WITHOUT ANY WARRANTY; without even the implied warranty of
25  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files
26  GIMPACT-LICENSE-LGPL.TXT, GIMPACT-LICENSE-ZLIB.TXT and GIMPACT-LICENSE-BSD.TXT for more details.
27 
28 -----------------------------------------------------------------------------
29 */
30 
31 #include "gim_contact.h"
32 
33 #define MAX_COINCIDENT 8
34 
36  const gim_contact_array& contacts, bool normal_contact_average)
37 {
38  clear();
39 
40  if (contacts.size() == 1)
41  {
42  push_back(contacts.back());
43  return;
44  }
45 
46  gim_array<GIM_RSORT_TOKEN> keycontacts(contacts.size());
47  keycontacts.resize(contacts.size(), false);
48 
49  //fill key contacts
50 
51  GUINT i;
52 
53  for (i = 0; i < contacts.size(); i++)
54  {
55  keycontacts[i].m_key = contacts[i].calc_key_contact();
56  keycontacts[i].m_value = i;
57  }
58 
59  //sort keys
60  gim_heap_sort(keycontacts.pointer(), keycontacts.size(), GIM_RSORT_TOKEN_COMPARATOR());
61 
62  // Merge contacts
63 
64  GUINT coincident_count = 0;
65  btVector3 coincident_normals[MAX_COINCIDENT];
66 
67  GUINT last_key = keycontacts[0].m_key;
68  GUINT key = 0;
69 
70  push_back(contacts[keycontacts[0].m_value]);
71  GIM_CONTACT* pcontact = &back();
72 
73  for (i = 1; i < keycontacts.size(); i++)
74  {
75  key = keycontacts[i].m_key;
76  const GIM_CONTACT* scontact = &contacts[keycontacts[i].m_value];
77 
78  if (last_key == key) //same points
79  {
80  //merge contact
81  if (pcontact->m_depth - CONTACT_DIFF_EPSILON > scontact->m_depth) //)
82  {
83  *pcontact = *scontact;
84  coincident_count = 0;
85  }
86  else if (normal_contact_average)
87  {
88  if (btFabs(pcontact->m_depth - scontact->m_depth) < CONTACT_DIFF_EPSILON)
89  {
90  if (coincident_count < MAX_COINCIDENT)
91  {
92  coincident_normals[coincident_count] = scontact->m_normal;
93  coincident_count++;
94  }
95  }
96  }
97  }
98  else
99  { //add new contact
100 
101  if (normal_contact_average && coincident_count > 0)
102  {
103  pcontact->interpolate_normals(coincident_normals, coincident_count);
104  coincident_count = 0;
105  }
106 
107  push_back(*scontact);
108  pcontact = &back();
109  }
110  last_key = key;
111  }
112 }
113 
115 {
116  clear();
117 
118  if (contacts.size() == 1)
119  {
120  push_back(contacts.back());
121  return;
122  }
123 
124  GIM_CONTACT average_contact = contacts.back();
125 
126  for (GUINT i = 1; i < contacts.size(); i++)
127  {
128  average_contact.m_point += contacts[i].m_point;
129  average_contact.m_normal += contacts[i].m_normal * contacts[i].m_depth;
130  }
131 
132  //divide
133  GREAL divide_average = 1.0f / ((GREAL)contacts.size());
134 
135  average_contact.m_point *= divide_average;
136 
137  average_contact.m_normal *= divide_average;
138 
139  average_contact.m_depth = average_contact.m_normal.length();
140 
141  average_contact.m_normal /= average_contact.m_depth;
142 }
GREAL
#define GREAL
Definition: gim_math.h:37
btVector3::length
btScalar length() const
Return the length of the vector.
Definition: btVector3.h:257
gim_array
Very simple array container with fast access and simd memory.
Definition: gim_array.h:42
GIM_RSORT_TOKEN_COMPARATOR
Prototype for comparators.
Definition: gim_radixsort.h:121
GIM_CONTACT::interpolate_normals
void interpolate_normals(btVector3 *normals, int normal_count)
Definition: btContactProcessingStructs.h:88
GIM_CONTACT::m_depth
btScalar m_depth
Definition: btContactProcessingStructs.h:45
gim_contact_array::merge_contacts
void merge_contacts(const gim_contact_array &contacts, bool normal_contact_average=true)
Definition: gim_contact.cpp:35
gim_contact_array::merge_contacts_unique
void merge_contacts_unique(const gim_contact_array &contacts)
Definition: gim_contact.cpp:114
GUINT
#define GUINT
Definition: gim_math.h:40
GIM_CONTACT::m_point
btVector3 m_point
Definition: btContactProcessingStructs.h:43
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:497
gim_array::back
T & back()
Definition: gim_array.h:198
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
gim_array< GIM_CONTACT >::push_back
void push_back(const GIM_CONTACT &obj)
Definition: gim_array.h:213
GIM_CONTACT
The GIM_CONTACT is an internal GIMPACT structure, similar to btManifoldPoint.
Definition: btContactProcessingStructs.h:40
gim_contact.h
MAX_COINCIDENT
#define MAX_COINCIDENT
Definition: gim_contact.cpp:33
gim_array< GIM_CONTACT >::clear
void clear()
Definition: gim_array.h:110
gim_contact_array
Definition: gim_contact.h:129
gim_array::resize
void resize(GUINT size, bool call_constructor=true, const T &fillData=T())
Definition: gim_array.h:287
GIM_CONTACT::m_normal
btVector3 m_normal
Definition: btContactProcessingStructs.h:44
CONTACT_DIFF_EPSILON
#define CONTACT_DIFF_EPSILON
Definition: btContactProcessingStructs.h:36
gim_heap_sort
void gim_heap_sort(T *pArr, GUINT element_count, COMP_CLASS CompareFunc)
Definition: gim_radixsort.h:366
gim_array::size
GUINT size() const
Definition: gim_array.h:143