/// Compute the point states given two manifolds. The states pertain to the transition from manifold1
/// to manifold2. So state1 is either persist or remove while state2 is either add or persist.
public static void b2GetPointStates(b2PointState[] state1, b2PointState[] state2,
ref b2Manifold manifold1, ref b2Manifold manifold2)
{
for (int i = 0; i < b2Settings.b2_maxManifoldPoints; ++i)
{
state1[i] = b2PointState.b2_nullState;
state2[i] = b2PointState.b2_nullState;
}
// Detect persists and removes.
for (int i = 0; i < manifold1.pointCount; ++i)
{
b2ContactFeature id = manifold1.points[i].id;
state1[i] = b2PointState.b2_removeState;
for (int j = 0; j < manifold2.pointCount; ++j)
{
if (manifold2.points[j].id.Equals(id))
{
state1[i] = b2PointState.b2_persistState;
break;
}
}
}
// Detect persists and adds.
for (int i = 0; i < manifold2.pointCount; ++i)
{
b2ContactFeature id = manifold2.points[i].id;
state2[i] = b2PointState.b2_addState;
for (int j = 0; j < manifold1.pointCount; ++j)
{
if (manifold1.points[j].id.Equals(id))
{
state2[i] = b2PointState.b2_persistState;
break;
}
}
}
}
public override void PreSolve(b2Contact contact, ref b2Manifold oldManifold)
{
b2Manifold manifold = contact.GetManifold();
if (manifold.pointCount == 0)
{
return;
}
b2Fixture fixtureA = contact.GetFixtureA();
b2Fixture fixtureB = contact.GetFixtureB();
b2PointState[] state1 = new b2PointState[b2Settings.b2_maxManifoldPoints];
b2PointState[] state2 = new b2PointState[b2Settings.b2_maxManifoldPoints];
b2Collision.b2GetPointStates(state1, state2, ref oldManifold, ref manifold);
b2WorldManifold worldManifold = new b2WorldManifold();
contact.GetWorldManifold(ref worldManifold);
for (int i = 0; i < manifold.pointCount && m_pointCount < k_maxContactPoints; ++i)
{
ContactPoint cp = m_points[m_pointCount];
if (cp == null)
{
cp = new ContactPoint();
m_points[m_pointCount] = cp;
}
cp.fixtureA = fixtureA;
cp.fixtureB = fixtureB;
cp.position = worldManifold.points[i];
cp.normal = worldManifold.normal;
cp.state = state2[i];
++m_pointCount;
}
}
public override void PreSolve(Box2D.Dynamics.Contacts.b2Contact contact, ref Box2D.Collision.b2Manifold oldManifold)
{
b2Manifold manifold = contact.GetManifold();
if (manifold.pointCount == 0)
{
return;
}
b2Fixture fixtureA = contact.GetFixtureA();
b2Fixture fixtureB = contact.GetFixtureB();
b2PointState[] state1 = new b2PointState[b2Settings.b2_maxManifoldPoints];
b2PointState[] state2 = new b2PointState[b2Settings.b2_maxManifoldPoints];
b2Collision.b2GetPointStates(state1, state2, ref oldManifold, ref manifold);
b2WorldManifold worldManifold = new b2WorldManifold();
contact.GetWorldManifold(ref worldManifold);
for (int i = 0; i < manifold.pointCount && m_pointCount < k_maxContactPoints; ++i)
{
ContactPoint cp = m_points[m_pointCount];
cp.fixtureA = fixtureA;
cp.fixtureB = fixtureB;
cp.position = worldManifold.points[i];
cp.normal = worldManifold.normal;
cp.state = state2[i];
m_points[m_pointCount] = cp;
++m_pointCount;
}
}
