void BulletPhysics::BulletInternalTickCallback(btDynamicsWorld* world, btScalar timeStep)
{
// called after bullet sdk performs its internal step
CB_ASSERT(world);
CB_ASSERT(world->getWorldUserInfo());
BulletPhysics* bulletPhysics = static_cast<BulletPhysics*>(world->getWorldUserInfo());
CollisionPairs currentTickCollisionPairs;
// look at all existing collisions
btDispatcher* dispatcher = world->getDispatcher();
const int numManifolds = dispatcher->getNumManifolds();
for (int i = 0; i < numManifolds; i++)
{
// get the manifold which is the data corresponding to a contact point between two colliders
const btPersistentManifold* manifold = dispatcher->getManifoldByIndexInternal(i);
CB_ASSERT(manifold);
// get the colliding bodies
const btRigidBody* body0 = static_cast<const btRigidBody *>(manifold->getBody0());
const btRigidBody* body1 = static_cast<const btRigidBody *>(manifold->getBody1());
// swap them if need be
const bool swapped = body0 > body1;
const btRigidBody* sortedBody0 = swapped ? body1 : body0;
const btRigidBody* sortedBody1 = swapped ? body0 : body1;
// insert the collision pair into the set
const CollisionPair pair = std::make_pair(sortedBody0, sortedBody1);
currentTickCollisionPairs.insert(pair);
// if this is a new contact, send an event
if (bulletPhysics->m_PreviousTickCollisionPairs.find(pair) == bulletPhysics->m_PreviousTickCollisionPairs.end())
{
bulletPhysics->SendCollisionPairAddEvent(manifold, body0, body1);
}
}
CollisionPairs removedCollisionPairs;
// use set difference to see which collisions existed last tick but are no longer colliding
std::set_difference(bulletPhysics->m_PreviousTickCollisionPairs.begin(), bulletPhysics->m_PreviousTickCollisionPairs.end(),
currentTickCollisionPairs.begin(), currentTickCollisionPairs.end(),
std::inserter(removedCollisionPairs, removedCollisionPairs.begin()));
// send collision exit events
for (auto it = removedCollisionPairs.begin(); it != removedCollisionPairs.end(); ++it)
{
const btRigidBody* body0 = it->first;
const btRigidBody* body1 = it->second;
bulletPhysics->SendCollisionPairRemoveEvent(body0, body1);
}
// update the collision pairs
bulletPhysics->m_PreviousTickCollisionPairs = currentTickCollisionPairs;
}
void BulletPhysics::RemoveCollisionObject(btCollisionObject* obj)
{
// remove a collision object from the physics world
m_DynamicsWorld->removeCollisionObject(obj);
// remove the pointer from the collision contacts list
for (auto it = m_PreviousTickCollisionPairs.begin(); it != m_PreviousTickCollisionPairs.end(); )
{
// step the iterator by 1
auto next = it;
++next;
// remove the object from any currently happening collision
if (it->first == obj || it->second == obj)
{
SendCollisionPairRemoveEvent(it->first, it->second);
m_PreviousTickCollisionPairs.erase(it);
}
it = next;
}
// if the object was a rigid body
if (btRigidBody* body = btRigidBody::upcast(obj))
{
// delete the components of the body
delete body->getMotionState();
delete body->getCollisionShape();
delete body->getUserPointer();
for (int i = body->getNumConstraintRefs() - 1; i >= 0; i--)
{
btTypedConstraint* constraint = body->getConstraintRef(i);
m_DynamicsWorld->removeConstraint(constraint);
delete constraint;
}
}
delete obj;
}
void BulletOpenGLApplication::CheckForCollisionEvents() {
// keep a list of the collision pairs we
// found during the current update
CollisionPairs pairsThisUpdate;
// iterate through all of the manifolds in the dispatcher
for (int i = 0; i < m_pDispatcher->getNumManifolds(); ++i) {
// get the manifold
btPersistentManifold* pManifold = m_pDispatcher->getManifoldByIndexInternal(i);
// ignore manifolds that have
// no contact points.
if (pManifold->getNumContacts() > 0) {
// get the two rigid bodies involved in the collision
const btRigidBody* pBody0 = static_cast<const btRigidBody*>(pManifold->getBody0());
const btRigidBody* pBody1 = static_cast<const btRigidBody*>(pManifold->getBody1());
// always create the pair in a predictable order
// (use the pointer value..)
bool const swapped = pBody0 > pBody1;
const btRigidBody* pSortedBodyA = swapped ? pBody1 : pBody0;
const btRigidBody* pSortedBodyB = swapped ? pBody0 : pBody1;
// create the pair
CollisionPair thisPair = std::make_pair(pSortedBodyA, pSortedBodyB);
// insert the pair into the current list
pairsThisUpdate.insert(thisPair);
// if this pair doesn't exist in the list
// from the previous update, it is a new
// pair and we must send a collision event
if (m_pairsLastUpdate.find(thisPair) == m_pairsLastUpdate.end()) {
CollisionEvent((btRigidBody*)pBody0, (btRigidBody*)pBody1);
}
}
}
// create another list for pairs that
// were removed this update
CollisionPairs removedPairs;
// this handy function gets the difference beween
// two sets. It takes the difference between
// collision pairs from the last update, and this
// update and pushes them into the removed pairs list
std::set_difference( m_pairsLastUpdate.begin(), m_pairsLastUpdate.end(),
pairsThisUpdate.begin(), pairsThisUpdate.end(),
std::inserter(removedPairs, removedPairs.begin()));
// iterate through all of the removed pairs
// sending separation events for them
for (CollisionPairs::const_iterator iter = removedPairs.begin(); iter != removedPairs.end(); ++iter) {
SeparationEvent((btRigidBody*)iter->first, (btRigidBody*)iter->second);
}
// in the next iteration we'll want to
// compare against the pairs we found
// in this iteration
m_pairsLastUpdate = pairsThisUpdate;
}
void BulletPhysicsManager::BulletInternalTickCallback( btDynamicsWorld * const world, btScalar const timeStep ) {
assert( world );
assert( world->getWorldUserInfo() );
BulletPhysicsManager * const bulletPhysics = static_cast<BulletPhysicsManager*>( world->getWorldUserInfo() );
// TODO - iterating through all physics components probably isn't the fastest way to handle this...
for(std::vector<GameObject*>::iterator it = bulletPhysics->physicsObjects.begin(); it != bulletPhysics->physicsObjects.end(); ++it) {
GameObject* gameObject = (*it);
Dynamics* rigidBodyComponent = gameObject->getDynamics();
if(rigidBodyComponent != NULL) {
btRigidBody* rigidBody = dynamic_cast<BulletDynamics*>(rigidBodyComponent)->rigidBody;
float maxVelocity = rigidBodyComponent->getMaxVelocity();
if(maxVelocity >= 0.0f) {
btVector3 velocity = rigidBody->getLinearVelocity();
btScalar speed = velocity.length();
if(speed > maxVelocity) {
velocity *= maxVelocity/speed;
rigidBody->setLinearVelocity(velocity);
}
}
}
}
bulletPhysics->currentTickCollisionPairs.clear();
// look at all existing contacts
btDispatcher * const dispatcher = world->getDispatcher();
for ( int manifoldIdx=0; manifoldIdx<dispatcher->getNumManifolds(); ++manifoldIdx )
{
// get the "manifold", which is the set of data corresponding to a contact point
// between two physics objects
btPersistentManifold const * const manifold = dispatcher->getManifoldByIndexInternal( manifoldIdx );
assert( manifold );
if(manifold->getNumContacts() > 0) {
btCollisionObject const * const body0 = static_cast<btCollisionObject const *>(manifold->getBody0());
btCollisionObject const * const body1 = static_cast<btCollisionObject const *>(manifold->getBody1());
// always create the pair in a predictable order
bool const swapped = body0 > body1;
btCollisionObject const * const sortedBodyA = swapped ? body1 : body0;
btCollisionObject const * const sortedBodyB = swapped ? body0 : body1;
CollisionPair const thisPair = std::make_pair( sortedBodyA, sortedBodyB );
// TODO - why are there duplicate collisions? Probably shouldn't have to check if these objects have already collided this tick
if ( bulletPhysics->previousTickCollisionPairs.find( thisPair ) == bulletPhysics->previousTickCollisionPairs.end()
&& bulletPhysics->currentTickCollisionPairs.find( thisPair ) == bulletPhysics->currentTickCollisionPairs.end())
{
// this needs to happen before sending the collision add event, since we might remove one of the game objects
// as part of handling the event
bulletPhysics->currentTickCollisionPairs.insert( thisPair );
// this is a new contact, which wasn't in our list before. send an event to the game.
bulletPhysics->SendCollisionPairAddEvent( manifold, body0, body1 );
} else {
bulletPhysics->currentTickCollisionPairs.insert( thisPair );
}
}
}
CollisionPairs removedCollisionPairs;
// use the STL set difference function to find collision pairs that existed during the previous tick but not any more
std::set_difference( bulletPhysics->previousTickCollisionPairs.begin(), bulletPhysics->previousTickCollisionPairs.end(),
bulletPhysics->currentTickCollisionPairs.begin(), bulletPhysics->currentTickCollisionPairs.end(),
std::inserter( removedCollisionPairs, removedCollisionPairs.begin() ) );
for ( CollisionPairs::const_iterator it = removedCollisionPairs.begin(),
end = removedCollisionPairs.end(); it != end; ++it )
{
btCollisionObject const * const body0 = it->first;
btCollisionObject const * const body1 = it->second;
bulletPhysics->SendCollisionPairRemoveEvent( body0, body1 );
}
// the current tick becomes the previous tick. this is the way of all things.
bulletPhysics->previousTickCollisionPairs = bulletPhysics->currentTickCollisionPairs;
}
