/// <summary>
/// Updates the <see cref="ParticleEmitter"/> and all <see cref="Particle"/>s it has created.
/// </summary>
/// <param name="currentTime">The current time.</param>>
internal void Update(TickCount currentTime)
{
var forceEmit = false;
// Get the elapsed time
// On the first update, just assume 33 ms have elapsed
int elapsedTime;
if (_lastUpdateTime == TickCount.MinValue)
{
// This is the very first update
forceEmit = true;
_nextReleaseTime = currentTime;
elapsedTime = 33;
}
else
{
// Not the first update
elapsedTime = (int)Math.Min(MaxDeltaTime, currentTime - _lastUpdateTime);
}
_lastUpdateTime = currentTime;
// Update the emitter modifiers
EmitterModifiers.ProcessEmitter(this, elapsedTime);
// Check if the sprite is loaded
if (Sprite == null || Sprite.GrhData == null)
{
EmitterModifiers.RestoreEmitter(this);
return;
}
// Update the current time on the modifiers
ParticleModifiers.UpdateCurrentTime(currentTime);
// Update the sprite
Sprite.Update(currentTime);
// Check to spawn more particles
if (forceEmit || (RemainingLife != 0 && ReleaseAmount.Max > 0 && ReleaseRate.Max > 0))
{
// Do not allow the releasing catch-up time to exceed the _maxDeltaTime
if (_nextReleaseTime < currentTime - MaxDeltaTime)
{
_nextReleaseTime = currentTime - MaxDeltaTime;
}
// Keep calculating the releases until we catch up to the current time
var amountToRelease = 0;
while (_nextReleaseTime <= currentTime)
{
amountToRelease += ReleaseAmount.GetNext();
_nextReleaseTime += ReleaseRate.GetNext();
}
// Release the particles, if there are any
if (amountToRelease > 0)
{
ReleaseParticles(currentTime, amountToRelease);
}
}
else
{
// Set the next release time to now so that if the emitter starts releasing, it won't release a ton
// as it catches back up
_nextReleaseTime = currentTime - MaxDeltaTime;
}
// Update the particles
var hasUpdateModifiers = ParticleModifiers.HasUpdateModifiers;
var i = 0;
Vector2 minParticlePosition = Vector2.Zero;
Vector2 maxParticlePosition = Vector2.Zero;
Vector2 spriteSize = Sprite.Size;
while (i <= _lastAliveIndex)
{
var particle = _particles[i];
// Check if the particle has expired
if (particle.LifeEnd <= currentTime)
{
// We do NOT increment because once we expire the particle, this slot will become in use by
// another particle, so we will have to update at this index again
ExpireParticle(i);
continue;
}
// Process the particle with the modifiers
if (hasUpdateModifiers)
{
ParticleModifiers.ProcessUpdatedParticle(this, particle, elapsedTime);
}
// Update the particle
particle.Update(elapsedTime);
// Update the min/max origin offsets
Vector2 posMin = particle.Position;
Vector2 particleSize;
Vector2.Multiply(ref spriteSize, particle.Scale, out particleSize);
Vector2 posMax;
Vector2.Add(ref posMin, ref particleSize, out posMax);
if (posMin.X < minParticlePosition.X)
{
minParticlePosition.X = posMin.X;
}
if (posMin.Y < minParticlePosition.Y)
{
minParticlePosition.Y = posMin.Y;
}
if (posMax.X > maxParticlePosition.X)
{
maxParticlePosition.X = posMax.X;
}
if (posMax.Y > maxParticlePosition.Y)
{
maxParticlePosition.Y = posMax.Y;
}
++i;
}
_minParticlePosition = minParticlePosition;
_maxParticlePosition = maxParticlePosition;
EmitterModifiers.RestoreEmitter(this);
}
