/// <summary>
/// Emits a particle.
/// </summary>
/// <param name="type">The particle type to emit</param>
/// <param name="x">X point to emit from.</param>
/// <param name="y">Y point to emit from.</param>
public void Emit(ParticleDefinition type, float x, float y)
{
if (type.Owner != this)
{
throw new Exception("Particle type does not belong to this emitter!");
}
var p = CreateParticle();
p.next = FirstActive;
p.prev = null;
if (p.next != null)
{
p.next.prev = p;
}
p.Definition = type;
p.time = 0;
p.duration = type.Lifetime.Duration;
p.duration += type.Lifetime.Variance.Add * Random.Float();
p.duration -= type.Lifetime.Variance.Subtract * Random.Float();
if (p.duration == 0)
{
p.duration = DT;
}
float angle = type.Angle.From;
angle += type.Angle.Variance.Add * Random.Float();
angle -= type.Angle.Variance.Subtract * Random.Float();
var moveAngle = type.Motion.Angle;
moveAngle += type.Motion.AngleVariance.Add * Random.Float();
moveAngle -= type.Motion.AngleVariance.Subtract * Random.Float();
var distance = type.Motion.Distance;
distance += type.Motion.DistanceVariance.Add * Random.Float();
distance -= type.Motion.DistanceVariance.Subtract * Random.Float();
p.initialVelocity = (distance * DT) / p.duration; // assuming XNA fixed is 60fps
p.x = x;
p.y = y;
MathUtility.AngleXY(ref p.velX, ref p.velY, moveAngle, p.initialVelocity);
p.alphaRand += type.Alpha.Variance.Add * Random.Float();
p.alphaRand -= type.Alpha.Variance.Subtract * Random.Float();
p.scaleRand += type.Scale.Variance.Add * Random.Float();
p.scaleRand -= type.Scale.Variance.Subtract * Random.Float();
p.angleRand += type.Angle.Variance.Add * Random.Float();
p.angleRand -= type.Angle.Variance.Subtract * Random.Float();
p.accelX = type.Motion.Acceleration.X * DT;
p.accelY = type.Motion.Acceleration.Y * DT;
ParticleCount++;
FirstActive = p;
}