public void InitialisePlasticity(List <Particle> plst, float smoothing_radius, float k)
{
int pindex1, pindex2;
float distance, tempfloat;
if (SpringArray.Springarray == null)
{
ResetSprings();
}
pindex1 = 0;
foreach (Particle p in plst)
{
//if the particle is boundary move on to the next particle since we don't want moving particles to attach to the boundary
if (p.Ismovingboundary || p.Isstationaryboundary)
{
continue;
}
pindex2 = 0;
foreach (Particle p2 in plst)
{
//if the particle is a boundary move on to the next particle
if (p2.Ismovingboundary || p2.Isstationaryboundary)
{
continue;
}
Spring spring = new Spring();
Vector2 vector_between_particle_neighbour = new Vector2();
vector_between_particle_neighbour.X = p2.Position.X - p.Position.X;
vector_between_particle_neighbour.Y = p2.Position.Y - p.Position.Y;
distance = vector_between_particle_neighbour.Length();
if (0 < distance && distance < smoothing_radius && !SpringArray.Springarray[pindex1, pindex2])
{
spring.Point1 = pindex1;
spring.Point2 = pindex2;
spring.Restlength = distance;
tempfloat = rand.Next((int)(k * 10), (int)(k * 10 + 3));
if (p.Mass == 1 && p2.Mass == 1)
{
spring.Coefficient = tempfloat / 10;
}
else if (p.Mass == 0 && p2.Mass == 0)
{
spring.Coefficient = tempfloat / 20;
}
else
{
spring.Coefficient = k;
}
SpringArray.Springlst.Add(spring);
SpringArray.Springarray[pindex1, pindex2] = true;
SpringArray.Springarray[pindex2, pindex1] = true;
}
pindex2++;
}
pindex1++;
}
}
public void CalculateViscoElasticity(List <Particle> plst, float smoothing_radius, float k, float yield_ratio, float pconst, float dt)
{
int pindex, sindex, sp1index, sp2index;
float restlength, tolerable_def, distance_between_neighbour_particle, tempfloat;
Vector2 sdisplacement;
Vector2 temp;
//create springs
pindex = 0;
foreach (Particle p in plst)
{
foreach (N_Particle n in p.Neighbourlist)
{
N_Particle nparticle = new N_Particle();
Spring spring = new Spring();
nparticle = n;
if (!SpringArray.Springarray[pindex, nparticle.Particleindex])
{
SpringArray.Springarray[pindex, nparticle.Particleindex] = true;
spring.Point1 = pindex;
spring.Point2 = nparticle.Particleindex;
spring.Restlength = smoothing_radius;
tempfloat = rand.Next((int)(k * 10), (int)(k * 10 + 3));
spring.Coefficient = tempfloat / 10;
//spring.Coefficient = k;
SpringArray.Springlst.Add(spring);
}
}
pindex++;
}
//Alter the rest length of springs
sindex = 0;
foreach (Spring s in SpringArray.Springlst.ToList())
{
sp1index = s.Point1;
sp2index = s.Point2;
restlength = s.Restlength;
tolerable_def = yield_ratio * restlength;
temp.X = plst.ElementAt(sp2index).Position.X - plst.ElementAt(sp1index).Position.X;
temp.Y = plst.ElementAt(sp2index).Position.Y - plst.ElementAt(sp1index).Position.Y;
distance_between_neighbour_particle = temp.Length();
if (distance_between_neighbour_particle > (restlength + tolerable_def))
{
s.Restlength += dt * dt_scalefactor * pconst * (distance_between_neighbour_particle - restlength - tolerable_def);
}
else if (distance_between_neighbour_particle < (restlength - tolerable_def))
{
s.Restlength -= dt * dt_scalefactor * pconst * (restlength - tolerable_def - distance_between_neighbour_particle);
}
if (s.Restlength > smoothing_radius && sindex < plst.Count)
{
SpringArray.Springarray[sindex, sindex] = false;
SpringArray.Springlst.RemoveAt(sindex);
sindex--;
}
sindex++;
}
//update position of particle due to spring forces
sindex = 0;
foreach (Spring s in SpringArray.Springlst)
{
Vector2 sforce = new Vector2(0, 0);
sp1index = s.Point1;
sp2index = s.Point2;
restlength = s.Restlength;
sforce = s.CalculateForce(sforce, s, plst.ElementAt(sp1index), plst.ElementAt(sp2index));
sdisplacement = sforce * (1.0f - restlength / smoothing_radius) * dt * dt_scalefactor * dt * dt_scalefactor;
if (plst.ElementAt(sp1index).Ismovingboundary == false && plst.ElementAt(sp1index).Isstationaryboundary == false)
{
plst.ElementAt(sp1index).Position -= sdisplacement;
}
if (plst.ElementAt(sp2index).Ismovingboundary == false && plst.ElementAt(sp2index).Isstationaryboundary == false)
{
plst.ElementAt(sp2index).Position += sdisplacement;
}
sindex++;
}
}
