/// <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(Particle p, Vector2 where)
{
// first, call PickRandomDirection to figure out which way the particle
// will be moving. _velocity and acceleration's values will come from this.
Vector2 direction = PickRandomDirection();
// pick some random values for our particle
float velocity =
CalcHelper.RandomBetween(minInitialSpeed, maxInitialSpeed);
//_velocity = new Vector2(_velocity.X + vel, _velocity.Y + vel);
float acceleration =
CalcHelper.RandomBetween(minAcceleration, maxAcceleration);
float lifetime =
CalcHelper.RandomBetween(minLifetime, maxLifetime);
float scale =
CalcHelper.RandomBetween(minScale, maxScale);
float rotationSpeed =
CalcHelper.RandomBetween(minRotationSpeed, maxRotationSpeed);
// 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);
}