internal void QueryCallback(int proxyId)
{
Debug.Assert(0 <= proxyId && proxyId < _proxyCapacity);
// A proxy cannot form a pair with itself.
if (proxyId == _queryProxyId)
{
return;
}
// Check the tight fitting AABBs for overlap.
if (AABB.TestOverlap(ref _proxyPool[proxyId].aabb, ref _proxyPool[_queryProxyId].aabb) == false)
{
return;
}
// Grow the pair buffer as needed.
if (_pairCount == _pairCapacity)
{
Pair[] oldBuffer = _pairBuffer;
_pairCapacity *= 2;
_pairBuffer = new Pair[_pairCapacity];
Array.Copy(oldBuffer, _pairBuffer, _pairCount);
}
_pairBuffer[_pairCount].proxyIdA = Math.Min(proxyId, _queryProxyId);
_pairBuffer[_pairCount].proxyIdB = Math.Max(proxyId, _queryProxyId);
++_pairCount;
}
/// Query an AABB for overlapping proxies. The callback class
/// is called for each proxy that overlaps the supplied AABB.
public void Query(Action <int> callback, ref AABB aabb)
{
int count = 0;
stack[count++] = _root;
while (count > 0)
{
int nodeId = stack[--count];
if (nodeId == NullNode)
{
continue;
}
DynamicTreeNode node = _nodes[nodeId];
if (AABB.TestOverlap(ref node.aabb, ref aabb))
{
if (node.IsLeaf())
{
callback(node.userData);
}
else
{
Debug.Assert(count + 1 < k_stackSize);
stack[count++] = node.child1;
stack[count++] = node.child2;
}
}
}
}
/// Ray-cast against the proxies in the tree. This relies on the callback
/// to perform a exact ray-cast in the case were the proxy contains a shape.
/// The callback also performs the any collision filtering. This has performance
/// roughly equal to k * log(n), where k is the number of collisions and n is the
/// number of proxies in the tree.
/// @param input the ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
/// @param callback a callback class that is called for each proxy that is hit by the ray.
public void RayCast(RayCastCallback callback, ref RayCastInput input)
{
Vector2 p1 = input.p1;
Vector2 p2 = input.p2;
Vector2 r = p2 - p1;
Debug.Assert(r.LengthSquared() > 0.0f);
r.Normalize();
// v is perpendicular to the segment.
Vector2 v = MathUtils.Cross(1.0f, r);
Vector2 abs_v = MathUtils.Abs(v);
// Separating axis for segment (Gino, p80).
// |dot(v, p1 - c)| > dot(|v|, h)
float maxFraction = input.maxFraction;
// Build a bounding box for the segment.
AABB segmentAABB = new AABB();
{
Vector2 t = p1 + maxFraction * (p2 - p1);
segmentAABB.lowerBound = Vector2.Min(p1, t);
segmentAABB.upperBound = Vector2.Max(p1, t);
}
int count = 0;
stack[count++] = _root;
while (count > 0)
{
int nodeId = stack[--count];
if (nodeId == NullNode)
{
continue;
}
DynamicTreeNode node = _nodes[nodeId];
if (AABB.TestOverlap(ref node.aabb, ref segmentAABB) == false)
{
continue;
}
// Separating axis for segment (Gino, p80).
// |dot(v, p1 - c)| > dot(|v|, h)
Vector2 c = node.aabb.GetCenter();
Vector2 h = node.aabb.GetExtents();
float separation = Math.Abs(Vector2.Dot(v, p1 - c)) - Vector2.Dot(abs_v, h);
if (separation > 0.0f)
{
continue;
}
if (node.IsLeaf())
{
RayCastInput subInput;
subInput.p1 = input.p1;
subInput.p2 = input.p2;
subInput.maxFraction = maxFraction;
RayCastOutput output;
callback(out output, ref subInput, node.userData);
if (output.hit)
{
// Early exit.
if (output.fraction == 0.0f)
{
return;
}
maxFraction = output.fraction;
// Update segment bounding box.
{
Vector2 t = p1 + maxFraction * (p2 - p1);
segmentAABB.lowerBound = Vector2.Min(p1, t);
segmentAABB.upperBound = Vector2.Max(p1, t);
}
}
}
else
{
Debug.Assert(count + 1 < k_stackSize);
stack[count++] = node.child1;
stack[count++] = node.child2;
}
}
}
internal void Collide()
{
// Update awake contacts.
Contact c = _contactList;
while (c != null)
{
Fixture fixtureA = c.GetFixtureA();
Fixture fixtureB = c.GetFixtureB();
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
if (bodyA.IsSleeping && bodyB.IsSleeping)
{
c = c.GetNext();
continue;
}
// Is this contact flagged for filtering?
if ((c._flags & ContactFlags.Filter) == ContactFlags.Filter)
{
// Are both bodies static?
if (bodyA.IsStatic && bodyB.IsStatic)
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// Does a joint override collision?
if (bodyB.IsConnected(bodyA))
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// Check user filtering.
if (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._proxyId;
int proxyIdB = fixtureB._proxyId;
AABB aabbA;
_broadPhase.GetAABB(proxyIdA, out aabbA);
AABB aabbB;
_broadPhase.GetAABB(proxyIdB, out aabbB);
// Here we cull out contacts that cease to overlap.
if (AABB.TestOverlap(ref aabbA, ref aabbB) == false)
{
Contact cNuke = c;
c = cNuke.GetNext();
Destroy(cNuke);
continue;
}
// The contact persists.
c.Update(ContactListener);
c = c.GetNext();
}
}