public void Reset(ref TimeStep step, List <Contact> contacts)
{
_step = step;
_contacts = contacts;
int contactCount = contacts.Count;
int constraintCount = contactCount;
_constraints.Clear();
for (int i = 0; i < constraintCount; i++)
{
_constraints.Add(new ContactConstraint());
}
for (int i = 0; i < constraintCount; ++i)
{
Contact contact = contacts[i];
Fixture fixtureA = contact._fixtureA;
Fixture fixtureB = contact._fixtureB;
Shape shapeA = fixtureA.GetShape();
Shape shapeB = fixtureB.GetShape();
float radiusA = shapeA._radius;
float radiusB = shapeB._radius;
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
Manifold manifold;
contact.GetManifold(out manifold);
float friction = Settings.b2MixFriction(fixtureA.GetFriction(), fixtureB.GetFriction());
float restitution = Settings.b2MixRestitution(fixtureA.GetRestitution(), fixtureB.GetRestitution());
Vector2 vA = bodyA._linearVelocity;
Vector2 vB = bodyB._linearVelocity;
float wA = bodyA._angularVelocity;
float wB = bodyB._angularVelocity;
Debug.Assert(manifold._pointCount > 0);
WorldManifold worldManifold = new WorldManifold(ref manifold, ref bodyA._xf, radiusA, ref bodyB._xf, radiusB);
ContactConstraint cc = _constraints[i];
cc.bodyA = bodyA;
cc.bodyB = bodyB;
cc.manifold = manifold;
cc.normal = worldManifold._normal;
cc.pointCount = manifold._pointCount;
cc.friction = friction;
cc.restitution = restitution;
cc.localPlaneNormal = manifold._localPlaneNormal;
cc.localPoint = manifold._localPoint;
cc.radius = radiusA + radiusB;
cc.type = manifold._type;
for (int j = 0; j < cc.pointCount; ++j)
{
ManifoldPoint cp = manifold._points[j];
ContactConstraintPoint ccp = cc.points[j];
ccp.normalImpulse = cp.NormalImpulse;
ccp.tangentImpulse = cp.TangentImpulse;
ccp.localPoint = cp.LocalPoint;
ccp.rA = worldManifold._points[j] - bodyA._sweep.c;
ccp.rB = worldManifold._points[j] - bodyB._sweep.c;
float rnA = MathUtils.Cross(ccp.rA, cc.normal);
float rnB = MathUtils.Cross(ccp.rB, cc.normal);
rnA *= rnA;
rnB *= rnB;
float kNormal = bodyA._invMass + bodyB._invMass + bodyA._invI * rnA + bodyB._invI * rnB;
Debug.Assert(kNormal > Settings.b2_FLT_EPSILON);
ccp.normalMass = 1.0f / kNormal;
float kEqualized = bodyA._mass * bodyA._invMass + bodyB._mass * bodyB._invMass;
kEqualized += bodyA._mass * bodyA._invI * rnA + bodyB._mass * bodyB._invI * rnB;
Debug.Assert(kEqualized > Settings.b2_FLT_EPSILON);
ccp.equalizedMass = 1.0f / kEqualized;
Vector2 tangent = MathUtils.Cross(cc.normal, 1.0f);
float rtA = MathUtils.Cross(ccp.rA, tangent);
float rtB = MathUtils.Cross(ccp.rB, tangent);
rtA *= rtA;
rtB *= rtB;
float kTangent = bodyA._invMass + bodyB._invMass + bodyA._invI * rtA + bodyB._invI * rtB;
Debug.Assert(kTangent > Settings.b2_FLT_EPSILON);
ccp.tangentMass = 1.0f / kTangent;
// Setup a velocity bias for restitution.
ccp.velocityBias = 0.0f;
float vRel = Vector2.Dot(cc.normal, vB + MathUtils.Cross(wB, ccp.rB) - vA - MathUtils.Cross(wA, ccp.rA));
if (vRel < -Settings.b2_velocityThreshold)
{
ccp.velocityBias = -cc.restitution * vRel;
}
cc.points[j] = ccp;
}
// If we have two points, then prepare the block solver.
if (cc.pointCount == 2)
{
ContactConstraintPoint ccp1 = cc.points[0];
ContactConstraintPoint ccp2 = cc.points[1];
float invMassA = bodyA._invMass;
float invIA = bodyA._invI;
float invMassB = bodyB._invMass;
float invIB = bodyB._invI;
float rn1A = MathUtils.Cross(ccp1.rA, cc.normal);
float rn1B = MathUtils.Cross(ccp1.rB, cc.normal);
float rn2A = MathUtils.Cross(ccp2.rA, cc.normal);
float rn2B = MathUtils.Cross(ccp2.rB, cc.normal);
float k11 = invMassA + invMassB + invIA * rn1A * rn1A + invIB * rn1B * rn1B;
float k22 = invMassA + invMassB + invIA * rn2A * rn2A + invIB * rn2B * rn2B;
float k12 = invMassA + invMassB + invIA * rn1A * rn2A + invIB * rn1B * rn2B;
// Ensure a reasonable condition number.
float k_maxConditionNumber = 100.0f;
if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12))
{
// K is safe to invert.
cc.K = new Mat22(new Vector2(k11, k12), new Vector2(k12, k22));
cc.normalMass = cc.K.GetInverse();
}
else
{
// The constraints are redundant, just use one.
// TODO_ERIN use deepest?
cc.pointCount = 1;
}
}
_constraints[i] = cc;
}
}
void SolveTOI(ref TimeStep step)
{
// Reserve an island and a queue for TOI island solution.
_island.Reset(_bodyCount,
Settings.b2_maxTOIContactsPerIsland,
Settings.b2_maxTOIJointsPerIsland,
_contactManager.ContactListener);
//Simple one pass queue
//Relies on the fact that we're only making one pass
//through and each body can only be pushed/popped once.
//To push:
// queue[queueStart+queueSize++] = newElement;
//To pop:
// poppedElement = queue[queueStart++];
// --queueSize;
//#warning More Body array Allocs
int queueCapacity = _bodyCount;
Body[] queue = new Body[_bodyCount];
for (Body b = _bodyList; b != null; b = b._next)
{
b._flags &= ~BodyFlags.Island;
b._sweep.t0 = 0.0f;
}
for (Contact c = _contactManager._contactList; c != null; c = c._next)
{
// Invalidate TOI
c._flags &= ~(ContactFlags.Toi | ContactFlags.Island);
}
for (Joint j = _jointList; j != null; j = j._next)
{
j._islandFlag = false;
}
// Find TOI events and solve them.
for (;;)
{
// Find the first TOI.
Contact minContact = null;
float minTOI = 1.0f;
for (Contact c = _contactManager._contactList; c != null; c = c._next)
{
if ((c._flags & (ContactFlags.Slow | ContactFlags.NonSolid)) != ContactFlags.None)
{
continue;
}
// TODO_ERIN keep a counter on the contact, only respond to M TOIs per contact.
float toi = 1.0f;
if ((c._flags & ContactFlags.Toi) != ContactFlags.None)
{
// This contact has a valid cached TOI.
toi = c._toi;
}
else
{
// Compute the TOI for this contact.
Fixture s1 = c.GetFixtureA();
Fixture s2 = c.GetFixtureB();
Body b1 = s1.GetBody();
Body b2 = s2.GetBody();
if ((b1.IsStatic || b1.IsSleeping) && (b2.IsStatic || b2.IsSleeping))
{
continue;
}
// Put the sweeps onto the same time interval.
float t0 = b1._sweep.t0;
if (b1._sweep.t0 < b2._sweep.t0)
{
t0 = b2._sweep.t0;
b1._sweep.Advance(t0);
}
else if (b2._sweep.t0 < b1._sweep.t0)
{
t0 = b1._sweep.t0;
b2._sweep.Advance(t0);
}
Debug.Assert(t0 < 1.0f);
// Compute the time of impact.
toi = c.ComputeTOI(ref b1._sweep, ref b2._sweep);
//CalculateTimeOfImpact(c._fixtureA.GetShape(), b1._sweep, c._fixtureB.GetShape(), b2._sweep);
Debug.Assert(0.0f <= toi && toi <= 1.0f);
// If the TOI is in range ...
if (0.0f < toi && toi < 1.0f)
{
// Interpolate on the actual range.
toi = Math.Min((1.0f - toi) * t0 + toi, 1.0f);
}
c._toi = toi;
c._flags |= ContactFlags.Toi;
}
if (Settings.b2_FLT_EPSILON < toi && toi < minTOI)
{
// This is the minimum TOI found so far.
minContact = c;
minTOI = toi;
}
}
if (minContact == null || 1.0f - 100.0f * Settings.b2_FLT_EPSILON < minTOI)
{
// No more TOI events. Done!
break;
}
// Advance the bodies to the TOI.
Fixture s1_2 = minContact.GetFixtureA();
Fixture s2_2 = minContact.GetFixtureB();
Body b1_2 = s1_2.GetBody();
Body b2_2 = s2_2.GetBody();
b1_2.Advance(minTOI);
b2_2.Advance(minTOI);
// The TOI contact likely has some new contact points.
minContact.Update(_contactManager.ContactListener);
minContact._flags &= ~ContactFlags.Toi;
if ((minContact._flags & ContactFlags.Touch) == 0)
{
// This shouldn't happen. Numerical error?
//Debug.Assert(false);
continue;
}
// Build the TOI island. We need a dynamic seed.
Body seed = b1_2;
if (seed.IsStatic)
{
seed = b2_2;
}
// Reset island and queue.
_island.Clear();
int queueStart = 0; // starting index for queue
int queueSize = 0; // elements in queue
queue[queueStart + queueSize++] = seed;
seed._flags |= BodyFlags.Island;
// Perform a breadth first search (BFS) on the contact/joint graph.
while (queueSize > 0)
{
// Grab the next body off the stack and add it to the island.
Body b = queue[queueStart++];
--queueSize;
_island.Add(b);
// Make sure the body is awake.
b._flags &= ~BodyFlags.Sleep;
// To keep islands as small as possible, we don't
// propagate islands across static bodies.
if (b.IsStatic)
{
continue;
}
// Search all contacts connected to this body.
for (ContactEdge cEdge = b._contactList; cEdge != null; cEdge = cEdge.Next)
{
// Does the TOI island still have space for contacts?
if (_island._contacts.Count == _island._contactCapacity)
{
continue;
}
// Has this contact already been added to an island? Skip slow or non-solid contacts.
if ((cEdge.Contact._flags & (ContactFlags.Island | ContactFlags.Slow | ContactFlags.NonSolid)) != ContactFlags.None)
{
continue;
}
// Is this contact touching? For performance we are not updating this contact.
if ((cEdge.Contact._flags & ContactFlags.Touch) == 0)
{
continue;
}
_island.Add(cEdge.Contact);
cEdge.Contact._flags |= ContactFlags.Island;
// Update other body.
Body other = cEdge.Other;
// Was the other body already added to this island?
if ((other._flags & BodyFlags.Island) != BodyFlags.None)
{
continue;
}
// March forward, this can do no harm since this is the min TOI.
if (other.IsStatic == false)
{
other.Advance(minTOI);
other.WakeUp();
}
Debug.Assert(queueStart + queueSize < queueCapacity);
queue[queueStart + queueSize] = other;
++queueSize;
other._flags |= BodyFlags.Island;
}
for (JointEdge jEdge = b._jointList; jEdge != null; jEdge = jEdge.Next)
{
if (_island._jointCount == _island._jointCapacity)
{
continue;
}
if (jEdge.Joint._islandFlag == true)
{
continue;
}
_island.Add(jEdge.Joint);
jEdge.Joint._islandFlag = true;
Body other = jEdge.Other;
if ((other._flags & BodyFlags.Island) != BodyFlags.None)
{
continue;
}
if (!other.IsStatic)
{
other.Advance(minTOI);
other.WakeUp();
}
Debug.Assert(queueStart + queueSize < queueCapacity);
queue[queueStart + queueSize] = other;
++queueSize;
other._flags |= BodyFlags.Island;
}
}
TimeStep subStep;
subStep.warmStarting = false;
subStep.dt = (1.0f - minTOI) * step.dt;
subStep.inv_dt = 1.0f / subStep.dt;
subStep.dtRatio = 0.0f;
subStep.velocityIterations = step.velocityIterations;
subStep.positionIterations = step.positionIterations;
_island.SolveTOI(ref subStep);
// Post solve cleanup.
for (int i = 0; i < _island._bodyCount; ++i)
{
// Allow bodies to participate in future TOI islands.
Body b = _island._bodies[i];
b._flags &= ~BodyFlags.Island;
if ((b._flags & (BodyFlags.Sleep | BodyFlags.Frozen)) != BodyFlags.None)
{
continue;
}
if (b.IsStatic)
{
continue;
}
// Update fixtures (for broad-phase).
b.SynchronizeFixtures();
// Invalidate all contact TOIs associated with this body. Some of these
// may not be in the island because they were not touching.
for (ContactEdge ce = b._contactList; ce != null; ce = ce.Next)
{
ce.Contact._flags &= ~ContactFlags.Toi;
}
}
int contactCount = _island._contacts.Count;
for (int i = 0; i < contactCount; ++i)
{
// Allow contacts to participate in future TOI islands.
Contact c = _island._contacts[i];
c._flags &= ~(ContactFlags.Toi | ContactFlags.Island);
}
for (int i = 0; i < _island._jointCount; ++i)
{
// Allow joints to participate in future TOI islands.
Joint j = _island._joints[i];
j._islandFlag = false;
}
// Commit fixture proxy movements to the broad-phase so that new contacts are created.
// Also, some contacts can be destroyed.
_contactManager.FindNewContacts();
}
}
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();
}
}
// Broad-phase callback.
internal void AddPair(Fixture proxyUserDataA, Fixture proxyUserDataB)
{
Fixture fixtureA = proxyUserDataA;
Fixture fixtureB = proxyUserDataB;
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
// Are the fixtures on the same body?
if (bodyA == bodyB)
{
return;
}
// Are both bodies static?
if (bodyA.IsStatic && bodyB.IsStatic)
{
return;
}
// Does a contact already exist?
ContactEdge edge = bodyB.GetConactList();
while (edge != null)
{
if (edge.Other == bodyA)
{
Fixture fA = edge.Contact.GetFixtureA();
Fixture fB = edge.Contact.GetFixtureB();
if (fA == fixtureA && fB == fixtureB)
{
// A contact already exists.
return;
}
if (fA == fixtureB && fB == fixtureA)
{
// A contact already exists.
return;
}
}
edge = edge.Next;
}
// Does a joint override collision?
if (bodyB.IsConnected(bodyA))
{
return;
}
// Check user filtering.
if (ContactFilter.ShouldCollide(fixtureA, fixtureB) == false)
{
return;
}
// Call the factory.
Contact c = Contact.Create(fixtureA, fixtureB);
// Contact creation may swap fixtures.
fixtureA = c.GetFixtureA();
fixtureB = c.GetFixtureB();
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 Destroy(Contact c)
{
Fixture fixtureA = c.GetFixtureA();
Fixture fixtureB = c.GetFixtureB();
Body bodyA = fixtureA.GetBody();
Body bodyB = fixtureB.GetBody();
if (c._manifold._pointCount > 0)
{
ContactListener.EndContact(c);
}
// Remove from the world.
if (c._prev != null)
{
c._prev._next = c._next;
}
if (c._next != null)
{
c._next._prev = c._prev;
}
if (c == _contactList)
{
_contactList = c._next;
}
// Remove from body 1
if (c._nodeA.Prev != null)
{
c._nodeA.Prev.Next = c._nodeA.Next;
}
if (c._nodeA.Next != null)
{
c._nodeA.Next.Prev = c._nodeA.Prev;
}
if (c._nodeA == bodyA._contactList)
{
bodyA._contactList = c._nodeA.Next;
}
// Remove from body 2
if (c._nodeB.Prev != null)
{
c._nodeB.Prev.Next = c._nodeB.Next;
}
if (c._nodeB.Next != null)
{
c._nodeB.Next.Prev = c._nodeB.Prev;
}
if (c._nodeB == bodyB._contactList)
{
bodyB._contactList = c._nodeB.Next;
}
--_contactCount;
}