/// <summary>
/// InitializeParticle is overridden to add the appearance of wind.
/// </summary>
/// <param name="p">the particle to set up</param>
/// <param name="where">where the particle should be placed</param>
protected override void InitializeParticle(Particle3d p, Vector3 where)
{
base.InitializeParticle(p, where);
// the base is mostly good, but we want to simulate a little bit of wind
// heading to the right.
p.Acceleration = p.Acceleration + new Vector3(ParticleSystem3d.RandomBetween(2, 8), 0, 0);
}
/// <summary>
/// InitializeParticle randomizes some properties for a particle, then
/// calls initialize on it. It can be overriden by subclasses if they
/// want to modify the way particles are created. For example,
/// SmokePlumeParticleSystem overrides this function make all particles
/// accelerate to the right, simulating wind.
/// </summary>
/// <param name="p">the particle to initialize</param>
/// <param name="where">the position on the screen that the particle should be
/// </param>
protected virtual void InitializeParticle(Particle3d p, Vector3 where)
{
// Determine the initial particle direction
Vector3 direction = PickParticleDirection();
// pick some random values for our particle
float velocity = RandomBetween(minInitialSpeed, maxInitialSpeed);
float acceleration = RandomBetween(minAcceleration, maxAcceleration);
float lifetime = RandomBetween(minLifetime, maxLifetime);
float scale = RandomBetween(minScale, maxScale);
float rotationSpeed = RandomBetween(minRotationSpeed, maxRotationSpeed);
float orientation = RandomBetween(0, (float)Math.PI * 2);
// then initialize it with those random values. initialize will save those,
// and make sure it is marked as active.
p.Initialize(where, velocity * direction, acceleration * direction,
lifetime, scale, rotationSpeed, orientation);
}