private void ApplyGlobalForces(CpuParticle particle, float elapsedTime)
{
particle.Velocity += (Preset.Gravity + Velocity) * elapsedTime;
if (Preset.RandomAcceleration > 0)
{
float randomFactor = Preset.RandomAcceleration / 1.732f /* approx. sqrt(3) */;
particle.Velocity += RandomUtils.GetRandomVector3(
new Vector3(-randomFactor, -randomFactor, -randomFactor),
new Vector3(randomFactor, randomFactor, randomFactor));
}
}
private void ApplyEmitterForces(CpuParticle particle, float elapsedTime)
{
Vector3 particlePosition = particle.Position.ApplyOffset(PreTransformedPosition);
float particleDistance = particlePosition.Length();
Vector3 particleDirection = Vector3.Normalize(particlePosition);
if (particleDistance < Preset.EmitterRepelRange)
{
float repelFactor = 1 - (particleDistance / Preset.EmitterRepelRange);
particle.Velocity += particleDirection * repelFactor * Preset.EmitterRepelSpeed * elapsedTime;
}
if (particleDistance > Preset.EmitterSuctionRange)
{
float suctionFactor = (particleDistance / Preset.EmitterSuctionRange) - 1;
particle.Velocity -= particleDirection * suctionFactor * Preset.EmitterSuctionSpeed * elapsedTime;
}
}
/// <summary>
/// Adds a new particle
/// </summary>
/// <param name="position">The initial position of the particle</param>
/// <param name="parameters1">The initial configuration of this particle</param>
/// <param name="parameters2">The configuration this particle will take in its "second life"</param>
private void AddParticle(DoubleVector3 position, CpuParticleParametersStruct parameters1, CpuParticleParametersStruct parameters2)
{
if (_deadParticles.Count > 0)
{
CpuParticle particle = _deadParticles.Pop();
particle.Alive = true;
particle.Position = position;
particle.Velocity = default(Vector3);
particle.Parameters1 = parameters1;
particle.Parameters2 = parameters2;
particle.Color = parameters1.Color;
particle.SecondLife = false;
_firstLifeParticles.Add(particle);
}
else
{
_firstLifeParticles.Add(new CpuParticle(position, parameters1, parameters2));
}
}
/// <summary>
/// Updates a specific particle
/// </summary>
/// <param name="particle">The particle to update</param>
/// <param name="elapsedTime">How many seconds have passed since the update of this particle</param>
private void UpdateParticle(CpuParticle particle, float elapsedTime)
{
ApplyGlobalForces(particle, elapsedTime);
ApplyEmitterForces(particle, elapsedTime);
particle.Update(elapsedTime);
}