1 /* 2 * Copyright (c) 2006-2009 Erin Catto http://www.box2d.org 3 * 4 * This software is provided 'as-is', without any express or implied 5 * warranty. In no event will the authors be held liable for any damages 6 * arising from the use of this software. 7 * Permission is granted to anyone to use this software for any purpose, 8 * including commercial applications, and to alter it and redistribute it 9 * freely, subject to the following restrictions: 10 * 1. The origin of this software must not be misrepresented; you must not 11 * claim that you wrote the original software. If you use this software 12 * in a product, an acknowledgment in the product documentation would be 13 * appreciated but is not required. 14 * 2. Altered source versions must be plainly marked as such, and must not be 15 * misrepresented as being the original software. 16 * 3. This notice may not be removed or altered from any source distribution. 17 */ 18 19 #include <Box2D/Dynamics/b2ContactManager.h> 20 #include <Box2D/Dynamics/b2Body.h> 21 #include <Box2D/Dynamics/b2Fixture.h> 22 #include <Box2D/Dynamics/b2WorldCallbacks.h> 23 #include <Box2D/Dynamics/Contacts/b2Contact.h> 24 25 b2ContactFilter b2_defaultFilter; 26 b2ContactListener b2_defaultListener; 27 28 b2ContactManager::b2ContactManager() 29 { 30 m_contactList = NULL; 31 m_contactCount = 0; 32 m_contactFilter = &b2_defaultFilter; 33 m_contactListener = &b2_defaultListener; 34 m_allocator = NULL; 35 } 36 37 void b2ContactManager::Destroy(b2Contact* c) 38 { 39 b2Fixture* fixtureA = c->GetFixtureA(); 40 b2Fixture* fixtureB = c->GetFixtureB(); 41 b2Body* bodyA = fixtureA->GetBody(); 42 b2Body* bodyB = fixtureB->GetBody(); 43 44 if (m_contactListener && c->IsTouching()) 45 { 46 m_contactListener->EndContact(c); 47 } 48 49 // Remove from the world. 50 if (c->m_prev) 51 { 52 c->m_prev->m_next = c->m_next; 53 } 54 55 if (c->m_next) 56 { 57 c->m_next->m_prev = c->m_prev; 58 } 59 60 if (c == m_contactList) 61 { 62 m_contactList = c->m_next; 63 } 64 65 // Remove from body 1 66 if (c->m_nodeA.prev) 67 { 68 c->m_nodeA.prev->next = c->m_nodeA.next; 69 } 70 71 if (c->m_nodeA.next) 72 { 73 c->m_nodeA.next->prev = c->m_nodeA.prev; 74 } 75 76 if (&c->m_nodeA == bodyA->m_contactList) 77 { 78 bodyA->m_contactList = c->m_nodeA.next; 79 } 80 81 // Remove from body 2 82 if (c->m_nodeB.prev) 83 { 84 c->m_nodeB.prev->next = c->m_nodeB.next; 85 } 86 87 if (c->m_nodeB.next) 88 { 89 c->m_nodeB.next->prev = c->m_nodeB.prev; 90 } 91 92 if (&c->m_nodeB == bodyB->m_contactList) 93 { 94 bodyB->m_contactList = c->m_nodeB.next; 95 } 96 97 // Call the factory. 98 b2Contact::Destroy(c, m_allocator); 99 --m_contactCount; 100 } 101 102 // This is the top level collision call for the time step. Here 103 // all the narrow phase collision is processed for the world 104 // contact list. 105 void b2ContactManager::Collide() 106 { 107 // Update awake contacts. 108 b2Contact* c = m_contactList; 109 while (c) 110 { 111 b2Fixture* fixtureA = c->GetFixtureA(); 112 b2Fixture* fixtureB = c->GetFixtureB(); 113 int32 indexA = c->GetChildIndexA(); 114 int32 indexB = c->GetChildIndexB(); 115 b2Body* bodyA = fixtureA->GetBody(); 116 b2Body* bodyB = fixtureB->GetBody(); 117 118 // Is this contact flagged for filtering? 119 if (c->m_flags & b2Contact::e_filterFlag) 120 { 121 // Should these bodies collide? 122 if (bodyB->ShouldCollide(bodyA) == false) 123 { 124 b2Contact* cNuke = c; 125 c = cNuke->GetNext(); 126 Destroy(cNuke); 127 continue; 128 } 129 130 // Check user filtering. 131 if (m_contactFilter && m_contactFilter->ShouldCollide(fixtureA, fixtureB) == false) 132 { 133 b2Contact* cNuke = c; 134 c = cNuke->GetNext(); 135 Destroy(cNuke); 136 continue; 137 } 138 139 // Clear the filtering flag. 140 c->m_flags &= ~b2Contact::e_filterFlag; 141 } 142 143 bool activeA = bodyA->IsAwake() && bodyA->m_type != b2_staticBody; 144 bool activeB = bodyB->IsAwake() && bodyB->m_type != b2_staticBody; 145 146 // At least one body must be awake and it must be dynamic or kinematic. 147 if (activeA == false && activeB == false) 148 { 149 c = c->GetNext(); 150 continue; 151 } 152 153 int32 proxyIdA = fixtureA->m_proxies[indexA].proxyId; 154 int32 proxyIdB = fixtureB->m_proxies[indexB].proxyId; 155 bool overlap = m_broadPhase.TestOverlap(proxyIdA, proxyIdB); 156 157 // Here we destroy contacts that cease to overlap in the broad-phase. 158 if (overlap == false) 159 { 160 b2Contact* cNuke = c; 161 c = cNuke->GetNext(); 162 Destroy(cNuke); 163 continue; 164 } 165 166 // The contact persists. 167 c->Update(m_contactListener); 168 c = c->GetNext(); 169 } 170 } 171 172 void b2ContactManager::FindNewContacts() 173 { 174 m_broadPhase.UpdatePairs(this); 175 } 176 177 void b2ContactManager::AddPair(void* proxyUserDataA, void* proxyUserDataB) 178 { 179 b2FixtureProxy* proxyA = (b2FixtureProxy*)proxyUserDataA; 180 b2FixtureProxy* proxyB = (b2FixtureProxy*)proxyUserDataB; 181 182 b2Fixture* fixtureA = proxyA->fixture; 183 b2Fixture* fixtureB = proxyB->fixture; 184 185 int32 indexA = proxyA->childIndex; 186 int32 indexB = proxyB->childIndex; 187 188 b2Body* bodyA = fixtureA->GetBody(); 189 b2Body* bodyB = fixtureB->GetBody(); 190 191 // Are the fixtures on the same body? 192 if (bodyA == bodyB) 193 { 194 return; 195 } 196 197 // TODO_ERIN use a hash table to remove a potential bottleneck when both 198 // bodies have a lot of contacts. 199 // Does a contact already exist? 200 b2ContactEdge* edge = bodyB->GetContactList(); 201 while (edge) 202 { 203 if (edge->other == bodyA) 204 { 205 b2Fixture* fA = edge->contact->GetFixtureA(); 206 b2Fixture* fB = edge->contact->GetFixtureB(); 207 int32 iA = edge->contact->GetChildIndexA(); 208 int32 iB = edge->contact->GetChildIndexB(); 209 210 if (fA == fixtureA && fB == fixtureB && iA == indexA && iB == indexB) 211 { 212 // A contact already exists. 213 return; 214 } 215 216 if (fA == fixtureB && fB == fixtureA && iA == indexB && iB == indexA) 217 { 218 // A contact already exists. 219 return; 220 } 221 } 222 223 edge = edge->next; 224 } 225 226 // Does a joint override collision? Is at least one body dynamic? 227 if (bodyB->ShouldCollide(bodyA) == false) 228 { 229 return; 230 } 231 232 // Check user filtering. 233 if (m_contactFilter && m_contactFilter->ShouldCollide(fixtureA, fixtureB) == false) 234 { 235 return; 236 } 237 238 // Call the factory. 239 b2Contact* c = b2Contact::Create(fixtureA, indexA, fixtureB, indexB, m_allocator); 240 if (c == NULL) 241 { 242 return; 243 } 244 245 // Contact creation may swap fixtures. 246 fixtureA = c->GetFixtureA(); 247 fixtureB = c->GetFixtureB(); 248 indexA = c->GetChildIndexA(); 249 indexB = c->GetChildIndexB(); 250 bodyA = fixtureA->GetBody(); 251 bodyB = fixtureB->GetBody(); 252 253 // Insert into the world. 254 c->m_prev = NULL; 255 c->m_next = m_contactList; 256 if (m_contactList != NULL) 257 { 258 m_contactList->m_prev = c; 259 } 260 m_contactList = c; 261 262 // Connect to island graph. 263 264 // Connect to body A 265 c->m_nodeA.contact = c; 266 c->m_nodeA.other = bodyB; 267 268 c->m_nodeA.prev = NULL; 269 c->m_nodeA.next = bodyA->m_contactList; 270 if (bodyA->m_contactList != NULL) 271 { 272 bodyA->m_contactList->prev = &c->m_nodeA; 273 } 274 bodyA->m_contactList = &c->m_nodeA; 275 276 // Connect to body B 277 c->m_nodeB.contact = c; 278 c->m_nodeB.other = bodyA; 279 280 c->m_nodeB.prev = NULL; 281 c->m_nodeB.next = bodyB->m_contactList; 282 if (bodyB->m_contactList != NULL) 283 { 284 bodyB->m_contactList->prev = &c->m_nodeB; 285 } 286 bodyB->m_contactList = &c->m_nodeB; 287 288 // Wake up the bodies 289 if (fixtureA->IsSensor() == false && fixtureB->IsSensor() == false) 290 { 291 bodyA->SetAwake(true); 292 bodyB->SetAwake(true); 293 } 294 295 ++m_contactCount; 296 } 297
