public void ApplyForce(SimObject simObject)
{
//get the direction vector
direction = simObjectA.CurrPosition - simObjectB.CurrPosition;
//check for zero vector
if (direction != Vector3.Zero)
{
//get length
currLength = direction.Length();
//normalize
direction.Normalize();
//add spring force
force = -stiffness * ((currLength - restLength) * direction);
//add spring damping force
force += -damping * Vector3.Dot(simObjectA.CurrVelocity - simObjectB.CurrVelocity, direction) * direction;
//apply the equal and opposite forces to the objects
simObjectA.ResultantForce += force;
simObjectB.ResultantForce += -force;
}
}
public override void Integrate(Vector3 acceleration, SimObject simObject)
{
//calculate new position using the velocity at current time
simObject.CurrPosition += simObject.CurrVelocity * fixedTimeStep;
//calculate new velocity using the acceleration at current time
simObject.CurrVelocity += acceleration * fixedTimeStep;
}
public override void Integrate(Vector3 acceleration, SimObject simObject)
{
newPosition = (2 - drag) * simObject.CurrPosition
- (1 - drag) * simObject.PrevPosition
+ acceleration * fixedTimeStep * fixedTimeStep;
simObject.PrevPosition = simObject.CurrPosition;
simObject.CurrPosition = newPosition;
}
public Spring(float stiffness, float damping, SimObject simObjectA, SimObject simObjectB, float restLength)
: base()
{
this.stiffness = stiffness;
this.damping = damping;
this.simObjectA = simObjectA;
this.simObjectB = simObjectB;
this.restLength = restLength;
}
public void AddSpring(float stiffness, float damping, SimObject simObjA, SimObject simObjB)
{
Spring spring = new Spring(stiffness, damping, simObjA, simObjB);
springs.Add(spring);
}
public void AddSimObject(SimObject simObject)
{
simObjects.Add(simObject);
}
//------------------------------------------------------------
public LengthConstraint(float length, SimObject simObj1, SimObject simObj2)
{
this.length = length;
this.simObj1 = simObj1;
this.simObj2 = simObj2;
}
public void ApplyForce(SimObject simObject)
{
simObject.ResultantForce += simObject.Mass * acceleration;
}
public abstract void Integrate(Vector3 acceleration, SimObject simObject);
public void ApplyForce(SimObject simObject)
{
simObject.ResultantForce += - dragCoefficient * simObject.CurrVelocity;
}
//------------------------------------------------------
public PointConstraint(Vector3 point, SimObject simObject)
{
this.point = point;
this.simObject = simObject;
}
//-----------------------------------------------------------
public Spring(float stiffness, float damping, SimObject simObjectA, SimObject simObjectB)
: this(stiffness, damping, simObjectA, simObjectB, (simObjectA.CurrPosition - simObjectB.CurrPosition).Length())
{
}
