protected internal override void GetContactInformation(int index, out ContactInformation info)
{
info.Contact = ContactManifold.contacts.Elements[index];
//Find the contact's normal force.
float totalNormalImpulse = 0;
info.NormalImpulse = 0;
for (int i = 0; i < contactConstraint.penetrationConstraints.Count; i++)
{
totalNormalImpulse += contactConstraint.penetrationConstraints.Elements[i].accumulatedImpulse;
if (contactConstraint.penetrationConstraints.Elements[i].contact == info.Contact)
{
info.NormalImpulse = contactConstraint.penetrationConstraints.Elements[i].accumulatedImpulse;
}
}
//Compute friction force. Since we are using central friction, this is 'faked.'
float radius;
Vector3.Distance(ref contactConstraint.slidingFriction.manifoldCenter, ref info.Contact.Position, out radius);
if (totalNormalImpulse > 0)
info.FrictionImpulse = (info.NormalImpulse / totalNormalImpulse) * (contactConstraint.slidingFriction.accumulatedImpulse.Length() + contactConstraint.twistFriction.accumulatedImpulse * radius);
else
info.FrictionImpulse = 0;
//Compute relative velocity
Vector3 velocity;
//If the pair is handling some type of query and does not actually have supporting entities, then consider the velocity contribution to be zero.
if (EntityA != null)
{
Vector3.Subtract(ref info.Contact.Position, ref EntityA.position, out velocity);
Vector3.Cross(ref EntityA.angularVelocity, ref velocity, out velocity);
Vector3.Add(ref velocity, ref EntityA.linearVelocity, out info.RelativeVelocity);
}
else
info.RelativeVelocity = new Vector3();
if (EntityB != null)
{
Vector3.Subtract(ref info.Contact.Position, ref EntityB.position, out velocity);
Vector3.Cross(ref EntityB.angularVelocity, ref velocity, out velocity);
Vector3.Add(ref velocity, ref EntityB.linearVelocity, out velocity);
Vector3.Subtract(ref info.RelativeVelocity, ref velocity, out info.RelativeVelocity);
}
info.Pair = this;
}
