src/BulletCollision/Gimpact/btContactProcessing.cpp

   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
  25 struct CONTACT_KEY_TOKEN
  26 {
  27         unsigned int m_key;
  28         int m_value;
  29         CONTACT_KEY_TOKEN()
  30     {
  31     }
  32
  33     CONTACT_KEY_TOKEN(unsigned int key,int token)
  34     {
  35         m_key = key;
  36         m_value =  token;
  37     }
  38
  39     CONTACT_KEY_TOKEN(const CONTACT_KEY_TOKEN& rtoken)
  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 };
  56
  57 class CONTACT_KEY_TOKEN_COMP
  58 {
  59         public:
  60
  61                 bool operator() ( const CONTACT_KEY_TOKEN& a, const CONTACT_KEY_TOKEN& b ) const
  62                 {
  63                         return ( a < b );
  64                 }
  65 };
  66
  67
  68 void btContactArray::merge_contacts(
  69         const btContactArray & contacts, bool normal_contact_average)
  70 {
  71         clear();
  72
  73         int i;
  74         if(contacts.size()==0) return;
  75
  76
  77         if(contacts.size()==1)
  78         {
  79                 push_back(contacts[0]);
  80                 return;
  81         }
  82
  83         btAlignedObjectArray<CONTACT_KEY_TOKEN> keycontacts;
  84
  85         keycontacts.reserve(contacts.size());
  86
  87         //fill key contacts
  88
  89         for ( i = 0;i<contacts.size() ;i++ )
  90         {
  91                 keycontacts.push_back(CONTACT_KEY_TOKEN(contacts[i].calc_key_contact(),i));
  92         }
  93
  94         //sort keys
  95         keycontacts.quickSort(CONTACT_KEY_TOKEN_COMP());
  96
  97         // Merge contacts
  98         int coincident_count=0;
  99         btVector3 coincident_normals[MAX_COINCIDENT];
 100
 101         unsigned int last_key = keycontacts[0].m_key;
 102         unsigned int key = 0;
 103
 104         push_back(contacts[keycontacts[0].m_value]);
 105
 106         GIM_CONTACT * pcontact = &(*this)[0];
 107
 108         for( i=1;i<keycontacts.size();i++)
 109         {
 110             key = keycontacts[i].m_key;
 111                 const GIM_CONTACT * scontact = &contacts[keycontacts[i].m_value];
 112
 113                 if(last_key ==  key)//same points
 114                 {
 115                         //merge contact
 116                         if(pcontact->m_depth - CONTACT_DIFF_EPSILON > scontact->m_depth)//)
 117                         {
 118                                 *pcontact = *scontact;
 119                 coincident_count = 0;
 120                         }
 121                         else if(normal_contact_average)
 122                         {
 123                                 if(btFabs(pcontact->m_depth - scontact->m_depth)<CONTACT_DIFF_EPSILON)
 124                 {
 125                     if(coincident_count<MAX_COINCIDENT)
 126                     {
 127                         coincident_normals[coincident_count] = scontact->m_normal;
 128                         coincident_count++;
 129                     }
 130                 }
 131                         }
 132                 }
 133                 else
 134                 {//add new contact
 135
 136                     if(normal_contact_average && coincident_count>0)
 137                     {
 138                         pcontact->interpolate_normals(coincident_normals,coincident_count);
 139                         coincident_count = 0;
 140                     }
 141
 142                     push_back(*scontact);
 143                     pcontact = &(*this)[this->size()-1];
 144         }
 145                 last_key = key;
 146         }
 147 }
 148
 149 void btContactArray::merge_contacts_unique(const btContactArray & contacts)
 150 {
 151         clear();
 152
 153         if(contacts.size()==0) return;
 154
 155         if(contacts.size()==1)
 156         {
 157                 push_back(contacts[0]);
 158                 return;
 159         }
 160
 161         GIM_CONTACT average_contact = contacts[0];
 162
 163         for (int i=1;i<contacts.size() ;i++ )
 164         {
 165                 average_contact.m_point += contacts[i].m_point;
 166                 average_contact.m_normal += contacts[i].m_normal * contacts[i].m_depth;
 167         }
 168
 169         //divide
 170         btScalar divide_average = 1.0f/((btScalar)contacts.size());
 171
 172         average_contact.m_point *= divide_average;
 173
 174         average_contact.m_normal *= divide_average;
 175
 176         average_contact.m_depth = average_contact.m_normal.length();
 177
 178         average_contact.m_normal /= average_contact.m_depth;
 179
 180 }
 181