public VerletConstraint(ref VerletParticle particle1, ref VerletParticle particle2, float restingDistance)
{
this.particle1 = particle1;
this.particle2 = particle2;
this.restingDistance = restingDistance;
}
void SatisfyConstraints()
{
for (int iter = 0; iter < numOfIter; ++iter)
{
//constrain in a box
for (int i = 0; i < particles.Count; ++i)
{
particles [i].position = Vector3.Min(Vector3.Max(particles [i].position, new Vector3(0, 0, 0)), new Vector3(1000, 1000, 1000));
}
//rest length constraints
//就是限制两个粒子间距是restlength：|p2-p1| = restlength
//求出位置差，两头分别移动一半距离
for (int i = 1; i < particles.Count; ++i)
{
VerletParticle prevParticle = particles [i - 1];
VerletParticle particle = particles [i];
Vector3 delta = particle.position - prevParticle.position;
//正常的计算
float deltaLength = delta.magnitude; //Mathf.Sqrt (delta * delta);
float diff = (deltaLength - restLength) / deltaLength;
prevParticle.position += delta * 0.5f * diff;
particle.position -= delta * 0.5f * diff;
//优化平方根（泰勒展开）
// delta = delta * restLength * restLength / ((Vector3.Dot (delta, delta) + restLength * restLength) - 0.5f);
// prevParticle.position += delta;
// particle.position -= delta;
}
}
}
public VerletConstraint(ref VerletParticle particle1, ref VerletParticle particle2)
{
this.particle1 = particle1;
this.particle2 = particle2;
// Assume resting distance as the current distance between the particles
restingDistance = (particle1.Position - particle2.Position).magnitude;
}
// Use this for initialization
void Start()
{
particles = new List <VerletParticle> ();
for (int i = 0; i < num; ++i)
{
VerletParticle newParticle = new VerletParticle();
newParticle.position = newParticle.prevPosition = transform.position + new Vector3(10 * i, 0, 0);
particles.Add(newParticle);
}
}
