/// <summary>
/// Add a particle to the system
/// </summary>
/// <param name="system"></param>
/// <param name="particle"></param>
public override void AddParticle(ParticleSystem system, Particle particle)
{
base.AddParticle(system, particle);
// pick a random X between X1 and X2
// then get the corresponding y
double x = ParticleSystem.random.NextDouble(X1, X2);
particle.Position = new Point(x + ParticleSystem.random.NextDouble(MinPositionOffset, MaxPositionOffset),
LinearEquation(x) + ParticleSystem.random.NextDouble(MinPositionOffset, MaxPositionOffset));
}
/// <summary>
/// Update the particle. Ignore the base and use the meatball update.
/// </summary>
/// <param name="particle"></param>
public override void UpdateParticle(Particle particle)
{
//base.UpdateParticle(particle);
double x = ParticleSystem.random.NextDouble(X1, X2);
// Get the meatball this particle is a part of.
((Meatball)mMeatballs[particle]).Update(this, x, LinearEquation(x));
}
/// <summary>
/// Create a meatball which adds three particles with springs to the system.
/// </summary>
/// <param name="system"></param>
/// <param name="particle"></param>
public override void AddParticle(ParticleSystem system, Particle particle)
{
//base.AddParticle(system, particle); // ignore the base
double x = ParticleSystem.random.NextDouble(X1, X2);
Meatball meatball = new Meatball(system, this, x, LinearEquation(x),
MinSpringConstant, MaxSpringConstant, MinDampeningConstant, MaxDampeningConstant,
MinRestLength, MaxRestLength, true);
// add each particle to the dictionary and its associated meatball.
foreach (Particle p in meatball.Particles)
{
mMeatballs.Add(p, meatball);
}
}
/// <summary>
/// Update the particle
/// </summary>
/// <param name="particle"></param>
public override void UpdateParticle(Particle particle)
{
base.UpdateParticle(particle);
// Find a new x and corresponding y
double x = ParticleSystem.random.NextDouble(X1, X2);
particle.Position = new Point(x + ParticleSystem.random.NextDouble(MinPositionOffset, MaxPositionOffset),
LinearEquation(x) + ParticleSystem.random.NextDouble(MinPositionOffset, MaxPositionOffset));
}
/// <summary>
/// Apply the spring force to ThisParticle and the ConnectedParticle
/// </summary>
/// <param name="particle"></param>
/// <returns></returns>
override public Vector ApplyForce(Particle particle)
{
// The particle to apply the force to must be one if the two particles which
// connects this spring
if (ThisParticle.Equals(particle) || ConnectedParticle.Equals(particle))
{
// if the particle is ThisParticle the the other particle is the ConnectedParticle and vice-versa
Particle con = ConnectedParticle;
if (ConnectedParticle.Equals(particle))
con = ThisParticle;
// Calculate the change in position (x and y) for the particle and its connection
double deltaX = particle.Position.X - con.Position.X;
double deltaY = particle.Position.Y - con.Position.Y;
// Calculate the change in velocity (x and y) for the particle and its connection
double deltaVX = particle.Velocity.X - con.Velocity.X;
double deltaVY = particle.Velocity.Y - con.Velocity.Y;
// Calculate the x and y forces generate on the particle by the spring
double fx1 = -(SpringConstant * (Math.Abs(deltaX) - RestLength) + DampingConstant * ((deltaVX * deltaX) / Math.Abs(deltaX))) * (deltaX / Math.Abs(deltaX));
double fy1 = -(SpringConstant * (Math.Abs(deltaY) - RestLength) + DampingConstant * ((deltaVY * deltaY) / Math.Abs(deltaY))) * (deltaY / Math.Abs(deltaY));
// The negative of that force is applied to the connected particle
double fx2 = -fx1;
double fy2 = -fy1;
// Apply the negative force
Vector cForce = con.Force;
con.Force = new Vector(cForce.X + fx2, cForce.Y + fy2);
// Return the spring force to be applied to this particle
return new Vector(fx1, fy1);
}
else
return new Vector(0, 0);
}
/// <summary>
/// Used by the Particle System to apply a force vector to a particle.
/// </summary>
/// <param name="particle"></param>
/// <returns></returns>
virtual public Vector ApplyForce(Particle particle) { return new Vector(); }
/// <summary>
/// Updates the particle by reinitializing its parameters. Used when a particle is first created and
/// when a particle is resurrected.
/// </summary>
/// <param name="particle"></param>
virtual public void UpdateParticle(Particle particle)
{
particle.Owner = this;
particle.Mass = ParticleSystem.random.NextDouble(MinMass, MaxMass);
particle.StartOpacity = this.StartOpacity;
particle.EndOpacity = this.EndOpacity;
particle.Force = new Vector(0, 0);
particle.Velocity = new Vector(
ParticleSystem.random.NextDouble(MinHorizontalVelocity, MaxHorizontalVelocity),
ParticleSystem.random.NextDouble(MinVerticalVelocity, MaxVerticalVelocity));
particle.LifeSpan = ParticleSystem.random.NextDouble(MinLifeSpan, MaxLifeSpan);
particle.BackgroundColors = this.ColorKeyFrames;
}
/// <summary>
/// Method which is used to perform additional processing when adding a particle to the system for the
/// first time.
/// </summary>
/// <param name="system"></param>
/// <param name="particle"></param>
virtual public void AddParticle(ParticleSystem system, Particle particle) {}
/// <summary>
/// Generates the particles for an emitter, called once at creation by the Particle System.
/// </summary>
/// <param name="system"></param>
virtual public void GenerateParticles(ParticleSystem system)
{
// Init the particles for the emitter
for (int i = 0; i < MaxParticles; i++)
{
Particle mParticle = new Particle();
UpdateParticle(mParticle);
this.AddParticle(system, mParticle);
system.Particles.Add(mParticle);
}
}
/// <summary>
/// Calculate all the forces acting on a particle at a given time
/// </summary>
/// <param name="particle"></param>
/// <param name="time"></param>
/// <returns></returns>
private Vector ComputeForces(Particle particle, double time)
{
// set all the forces for a particle at a time and position
double forceX = (particle.Mass * Gravity.X) - (particle.Velocity.X * Drag.X);
double forceY = (particle.Mass * Gravity.Y) - (particle.Velocity.Y * Drag.Y);
// If there are spring force connections on this particle then for every connection update
// the forces acting upon the particle
if (particle.Connections.Count > 0)
{
foreach (Spring s in particle.Connections)
{
// apply the spring force
Vector force = s.ApplyForce(particle);
forceX += force.X;
forceY += force.Y;
}
}
// for every other force in the global list of forces, apply and update the force.
foreach (Force f in Forces)
{
Vector force = f.ApplyForce(particle);
forceX += force.X;
forceY += force.Y;
}
return new Vector(forceX, forceY); // return the force vector.
}