/// <summary>
/// Updates the particle emitter bounds
/// </summary>
/// <param name="systemParams">System parameters</param>
public void UpdateBounds(ParticleSystemParams systemParams)
{
var bbox = SampleBBox(this, systemParams, 0.33f);
bbox = BoundingBox.Merge(bbox, SampleBBox(this, systemParams, 0.66f));
bbox = BoundingBox.Merge(bbox, SampleBBox(this, systemParams, 1f));
this.SetBoundingBox(bbox);
}
/// <summary>
/// Updates the internal bounding box
/// </summary>
protected virtual void UpdateBoundingBox()
{
var tmp = mergedBoundingBox;
mergedBoundingBox = new BoundingBox(
this.boundingBox.Minimum + this.Position,
this.boundingBox.Maximum + this.Position);
if (tmp != null)
{
mergedBoundingBox = BoundingBox.Merge(tmp.Value, mergedBoundingBox.Value);
}
}
/// <summary>
/// Samples a bounding box for the current emitter at the specified time
/// </summary>
/// <param name="emitter">Emitter</param>
/// <param name="systemParams">Particle system parameters</param>
/// <param name="time">Time</param>
/// <returns>Returns the sampled bounding box</returns>
private static BoundingBox SampleBBox(ParticleEmitter emitter, ParticleSystemParams systemParams, float time)
{
//Initial position
Vector3 initialPos = Vector3.Zero;
Vector3 velocity = emitter.Velocity * systemParams.EmitterVelocitySensitivity;
float horizontalVelocity = Math.Max(systemParams.HorizontalVelocity.X, systemParams.HorizontalVelocity.Y);
//Max v velocity
Vector3 vVelocity = velocity;
vVelocity.Y *= Math.Max(systemParams.VerticalVelocity.X, systemParams.VerticalVelocity.Y);
//Max h velocity
Vector3 hVelocity1 = velocity;
hVelocity1.X *= horizontalVelocity * (float)Math.Cos(0);
hVelocity1.Z *= horizontalVelocity * (float)Math.Sin(0);
Vector3 hVelocity2 = velocity;
hVelocity2.X *= horizontalVelocity * (float)Math.Cos(1);
hVelocity2.Z *= horizontalVelocity * (float)Math.Sin(1);
//Final positions
Vector3 finalPosV = ComputeParticlePosition(
initialPos,
vVelocity,
systemParams.EndVelocity,
systemParams.MaxDuration * time,
time,
systemParams.Gravity);
Vector3 finalPosH1 = ComputeParticlePosition(
initialPos,
hVelocity1,
systemParams.EndVelocity,
systemParams.MaxDuration * time,
time,
systemParams.Gravity);
Vector3 finalPosH2 = ComputeParticlePosition(
initialPos,
hVelocity2,
systemParams.EndVelocity,
systemParams.MaxDuration * time,
time,
systemParams.Gravity);
float startSize = systemParams.MaxStartSize * 0.5f;
BoundingSphere initial = new BoundingSphere(initialPos + new Vector3(0, startSize, 0), startSize * 0.5f);
float endSize = systemParams.MaxEndSize * 0.5f;
BoundingSphere finalV = new BoundingSphere(finalPosV + new Vector3(0, endSize, 0), endSize * 0.5f);
BoundingSphere finalH1 = new BoundingSphere(finalPosH1 + new Vector3(0, endSize, 0), endSize * 0.5f);
BoundingSphere finalH2 = new BoundingSphere(finalPosH2 + new Vector3(0, endSize, 0), endSize * 0.5f);
var bbox = BoundingBox.FromSphere(initial);
bbox = BoundingBox.Merge(bbox, BoundingBox.FromSphere(finalV));
bbox = BoundingBox.Merge(bbox, BoundingBox.FromSphere(finalH1));
bbox = BoundingBox.Merge(bbox, BoundingBox.FromSphere(finalH2));
return(bbox);
}