/**
* Add a particle to the grid structure.
* \param hash cell hash, can be computed from the cellIndex (next parameter) using ComputeCellHash.
* \param cellIndex 3-dimensional index of the cell to add the particle to.
* \param p the particle that should be added to the grid.
*/
public void AddParticle(int hash, Vector3 cellIndex, ObiClothParticle p)
{
//See if the cell exists and insert the particle in it:
Cell cell = null;
if (cells.TryGetValue(hash,out cell)){
cell.AddParticle(p);
}else{
cell = new Cell(this,cellIndex,hash);
cell.AddParticle(p);
cells[hash] = cell;
}
}
public VirtualCollisionConstraint(Transform transform, ObiClothParticle particle, ObiClothParticle particle2, ObiClothParticle particle3,
Vector3 vpPosition,Vector3 vpBarycentricCoords, Rigidbody rigidbody, Vector3 point, Vector3 normal, float distance, float friction)
: base(transform,particle,rigidbody,point,normal,distance,friction)
{
this.particle2 = particle2;
this.particle3 = particle3;
this.vpPosition = vpPosition;
this.vpBarycentricCoords = vpBarycentricCoords;
this.vpWeight = ObiUtils.BarycentricInterpolation(particle.w,particle2.w,particle3.w,vpBarycentricCoords);
this.scaleFactor = ObiUtils.BarycentricExtrapolationScale(vpBarycentricCoords);
this.weightSum = vpWeight + rigidbodyWeight;
}
public SelfCollisionConstraint(Transform transform, ObiClothParticle particle1, ObiClothParticle particle2, Vector3 point, Vector3 normal, float distance, float friction)
: base(transform)
{
this.transform = transform;
this.particle1 = particle1;
this.particle2 = particle2;
this.point = point;
this.normal = normal;
this.distance = distance;
this.weightSum = particle1.w + particle2.w;
this.frictionCoeff = friction;
}
public CollisionConstraint(Transform transform, ObiClothParticle particle, Rigidbody rigidbody, Vector3 point, Vector3 normal, float distance, float friction)
: base(transform)
{
this.transform = transform;
this.particle = particle;
this.wspoint = point;
this.point = transform.InverseTransformPoint(point);
this.normal = transform.InverseTransformDirection(normal);
this.distance = distance;
this.rigidbody = rigidbody;
this.rigidbodyWeight = (rigidbody == null || rigidbody.isKinematic) ? 0 : 1/rigidbody.mass;
this.weightSum = particle.w + rigidbodyWeight;
this.frictionCoeff = friction;
}
public Vector3 wind = Vector3.zero; /**< Wind force vector expressed in world space.*/
#endregion Fields
#region Methods
public void ApplyAerodynamicsToParticle(ObiClothParticle p, Vector3 normal, Vector3 localSpaceWind, float dt)
{
Profiler.BeginSample("Aerodynamics");
if (enabled){
float halfAirDensity = airDensity * 0.5f; /// air density in kg/m3.
Vector3 relVelocity = p.velocity - localSpaceWind; //relative velocity between particle and wind force.
float relVelSqrMag = relVelocity.sqrMagnitude; //squared magnitude of relative velocity.
Vector3 relVelocityNorm = relVelocity.normalized; //direction of relative velocity.
// Calculate surface normal:
Vector3 surfNormal = normal.normalized * Mathf.Sign(Vector3.Dot(normal,relVelocityNorm));
// Calculate aerodynamic factor. This is just a fancy name for a common part of the lift and drag calculations.
float aerodynamicFactor = halfAirDensity * relVelSqrMag * p.areaContribution;
// Calculate dot product between the surface normal at the particle's position, and the relative velocity direction.
float dotNRV = Vector3.Dot(surfNormal,relVelocity.normalized);
// Calculate drag force:
float dragMagnitude = dragCoefficient * aerodynamicFactor;
Vector3 fDrag = - dragMagnitude * dotNRV * relVelocityNorm;
// Calculate lift force:
float liftMagnitude = liftCoefficient * aerodynamicFactor;
Vector3 fLift = liftMagnitude * dotNRV * Vector3.Cross(Vector3.Cross(surfNormal,relVelocityNorm),relVelocityNorm).normalized;
// Apply both forces as accelerations:
p.velocity += fDrag * p.w * dt; // a = F/m
p.velocity += fLift * p.w * dt; // a = F/m
}
Profiler.EndSample();
}
/**
* Removes the supplied particle from this cell, then destroys the cell if no particles are stored in it.
*/
public void RemoveParticle(ObiClothParticle p)
{
//Remove the particle from the cell.
particles.Remove(p);
//If the cell is now empty, remove the cell from the grid:
if (particles.Count == 0)
grid.cells.Remove(hash);
}
/**
* Adds to this cell a reference to the supplied particle.
*/
public void AddParticle(ObiClothParticle p)
{
//Add the particle index to the cell:
particles.Add(p);
}
/**
* If the supplied particle cell hash is equal to the one calculated from the supplied cellIndex, nothing is done. Else,
* the particle is removed from its current cell and then added to the cell indicated by cellIndex.
*/
public void UpdateParticle(ObiClothParticle p, Vector3 cellIndex)
{
int hash = ComputeCellHash(cellIndex);
if (hash != p.gridCellHash){
RemoveParticle(p.gridCellHash,p);
AddParticle(hash,cellIndex,p);
p.gridCellHash = hash;
}
}
/**
* Remove a particle from the grid structure.
* \param hash cell hash, can be computed using ComputeCellHash.
* \param p the particle that should be removed from the grid.
*/
public void RemoveParticle(int hash, ObiClothParticle p)
{
//See if the cell exists, and in that case, remove the particle from it:
Cell cell = null;
if (cells.TryGetValue(hash,out cell)){
cell.RemoveParticle(p);
}
}
