// Broad-phase callback.
internal void AddPair(FixtureProxy proxyA, FixtureProxy proxyB)
{
Fixture fixtureA = proxyA.fixture;
Fixture fixtureB = proxyB.fixture;
int indexA = proxyA.childIndex;
int indexB = proxyB.childIndex;
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
// Are the fixtures on the same body?
if (bodyA == bodyB)
{
return;
}
// Does a contact already exist?
ContactEdge edge = bodyB.GetContactList();
while (edge != null)
{
if (edge.Other == bodyA)
{
Fixture fA = edge.Contact.GetFixtureA();
Fixture fB = edge.Contact.GetFixtureB();
int iA = edge.Contact.GetChildIndexA();
int iB = edge.Contact.GetChildIndexB();
if (fA == fixtureA && fB == fixtureB && iA == indexA && iB == indexB)
{
// A contact already exists.
return;
}
if (fA == fixtureB && fB == fixtureA && iA == indexB && iB == indexA)
{
// A contact already exists.
return;
}
}
edge = edge.Next;
}
// Does a joint override collision? Is at least one body dynamic?
if (bodyB.ShouldCollide(bodyA) == false)
{
return;
}
// Check user filtering.
if (ContactFilter != null && ContactFilter.ShouldCollide(fixtureA, fixtureB) == false)
{
return;
}
// Call the factory.
Contact c = Contact.Create(fixtureA, indexA, fixtureB, indexB);
// Contact creation may swap fixtures.
fixtureA = c.GetFixtureA();
fixtureB = c.GetFixtureB();
indexA = c.GetChildIndexA();
indexB = c.GetChildIndexB();
bodyA = fixtureA.GetBody();
bodyB = fixtureB.GetBody();
// Insert into the world.
c._prev = null;
c._next = _contactList;
if (_contactList != null)
{
_contactList._prev = c;
}
_contactList = c;
// Connect to island graph.
// Connect to body A
c._nodeA.Contact = c;
c._nodeA.Other = bodyB;
c._nodeA.Prev = null;
c._nodeA.Next = bodyA._contactList;
if (bodyA._contactList != null)
{
bodyA._contactList.Prev = c._nodeA;
}
bodyA._contactList = c._nodeA;
// Connect to body B
c._nodeB.Contact = c;
c._nodeB.Other = bodyA;
c._nodeB.Prev = null;
c._nodeB.Next = bodyB._contactList;
if (bodyB._contactList != null)
{
bodyB._contactList.Prev = c._nodeB;
}
bodyB._contactList = c._nodeB;
++_contactCount;
}
internal void Collide()
{
// Update awake contacts.
Contact c = _contactList;
while (c != null)
{
Fixture fixtureA = c.GetFixtureA();
Fixture fixtureB = c.GetFixtureB();
int indexA = c.GetChildIndexA();
int indexB = c.GetChildIndexB();
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
if (bodyA.IsAwake() == false && bodyB.IsAwake() == false)
{
c = c.GetNext();
continue;
}
// Is this contact flagged for filtering?
if ((c._flags & ContactFlags.Filter) == ContactFlags.Filter)
{
// Should these bodies collide?
if (bodyB.ShouldCollide(bodyA) == false)
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// Check user filtering.
if (ContactFilter != null && ContactFilter.ShouldCollide(fixtureA, fixtureB) == false)
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// Clear the filtering flag.
c._flags &= ~ContactFlags.Filter;
}
int proxyIdA = fixtureA._proxies[indexA].proxyId;
int proxyIdB = fixtureB._proxies[indexB].proxyId;
bool overlap = _broadPhase.TestOverlap(proxyIdA, proxyIdB);
// Here we destroy contacts that cease to overlap in the broad-phase.
if (overlap == false)
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// The contact persists.
c.Update(ContactListener);
c = c.GetNext();
}
}