/// <summary>
/// Add an internal spring to this body.
/// </summary>
/// <param name="pointA">point mass on 1st end of the spring</param>
/// <param name="pointB">point mass on 2nd end of the spring</param>
/// <param name="springK">spring constant</param>
/// <param name="damping">spring damping</param>
public void addInternalSpring(int pointA, int pointB, float springK, float damping)
{
float dist = (mPointMasses[pointB].Position - mPointMasses[pointA].Position).magnitude;
InternalSpring s = new InternalSpring(pointA, pointB, dist, springK, damping);
mSprings.Add(s);
}
public override void accumulateInternalForces()
{
base.accumulateInternalForces();
// internal spring forces.
Vector2 force = new Vector2();
for (int i = 0; i < mSprings.Count; i++)
{
InternalSpring s = mSprings[i];
VectorTools.calculateSpringForce(ref mPointMasses[s.pointMassA].Position, ref mPointMasses[s.pointMassA].Velocity,
ref mPointMasses[s.pointMassB].Position, ref mPointMasses[s.pointMassB].Velocity,
s.springD, s.springK, s.damping,
ref force);
mPointMasses[s.pointMassA].Force.x += force.x;
mPointMasses[s.pointMassA].Force.y += force.y;
mPointMasses[s.pointMassB].Force.x -= force.x;
mPointMasses[s.pointMassB].Force.y -= force.y;
}
// shape matching forces.
if (mShapeMatchingOn)
{
Vector2 p = DerivedPos;
mBaseShape.transformVertices(ref p, DerivedAngle, ref mScale, ref mGlobalShape);
DerivedPos = p;
for (int i = 0; i < mPointMasses.Count; i++)
{
if (mShapeSpringK > 0)
{
if (!mKinematic)
{
VectorTools.calculateSpringForce(ref mPointMasses[i].Position, ref mPointMasses[i].Velocity,
ref mGlobalShape[i], ref mPointMasses[i].Velocity, 0.0f, mShapeSpringK, mShapeSpringDamp,
ref force);
}
else
{
Vector2 kinVel = Vector2.zero;
VectorTools.calculateSpringForce(ref mPointMasses[i].Position, ref mPointMasses[i].Velocity,
ref mGlobalShape[i], ref kinVel, 0.0f, mShapeSpringK, mShapeSpringDamp,
ref force);
}
mPointMasses[i].Force.x += force.x;
mPointMasses[i].Force.y += force.y;
}
}
}
}
/// <summary>
/// Add an internal spring to this body.
/// </summary>
/// <param name="pointA">point mass on 1st end of the spring</param>
/// <param name="pointB">point mass on 2nd end of the spring</param>
/// <param name="springK">spring constant</param>
/// <param name="damping">spring damping</param>
public void addInternalSpring(int pointA, int pointB, float springK, float damping)
{
float dist = (mPointMasses[pointB].Position - mPointMasses[pointA].Position).magnitude;
InternalSpring s = new InternalSpring(pointA, pointB, dist, springK, damping);
mSprings.Add(s);
}
