//===========================================================
// Particle System Update Functions
//===========================================================
//===========================================================
// Other Particle System Functions
//===========================================================
private void MakeButterflyFaceProperDirectionAndAdjustAnimationSpeed(DefaultAnimatedTexturedQuadParticle cParticle)
{
// Calculate the new Direction the Butterfly should face
Vector3 sFacingDirection = Vector3.Cross(cParticle.Velocity, Vector3.Up);
cParticle.Orientation = Orientation3D.GetQuaternionWithOrientation(sFacingDirection, Vector3.Up);
// Make the Butterfly animation go faster based on how fast it is moving upwards
float fNormalizedYVelocity = (cParticle.Velocity.Y + miButterflyMaxSpeed) / (miButterflyMaxSpeed * 2);
float fNewAnimationTime = MathHelper.Lerp(mfMaxTimeBetweenAnimationImages, mfMinTimeBetweenAnimationImages, fNormalizedYVelocity);
cParticle.Animation.CurrentAnimationsPictureRotationTime = fNewAnimationTime;
}
//===========================================================
// Particle Update Functions
//===========================================================
protected void KeepParticleInBox(DefaultAnimatedTexturedQuadParticle cParticle, float fElapsedTimeInSeconds)
{
bool bDirectionChanged = false;
// If the Particle is heading outside of the box
if ((cParticle.Position.X > msBoxMax.X && cParticle.Velocity.X > 0) ||
(cParticle.Position.X < msBoxMin.X && cParticle.Velocity.X < 0))
{
// Reverse it's velocity to keep it inside the box
cParticle.Velocity.X *= -1;
bDirectionChanged = true;
}
// If the Particle is heading outside of the box
if ((cParticle.Position.Y > msBoxMax.Y && cParticle.Velocity.Y > 0) ||
(cParticle.Position.Y < msBoxMin.Y && cParticle.Velocity.Y < 0))
{
// Reverse it's velocity to keep it inside the box
cParticle.Velocity.Y *= -1;
bDirectionChanged = true;
}
// If the Particle is heading outside of the box
if ((cParticle.Position.Z > msBoxMax.Z && cParticle.Velocity.Z > 0) ||
(cParticle.Position.Z < msBoxMin.Z && cParticle.Velocity.Z < 0))
{
// Reverse it's velocity to keep it inside the box
cParticle.Velocity.Z *= -1;
bDirectionChanged = true;
}
// If the Direction was changed
if (bDirectionChanged)
{
// Calculate the new Direction the Butterfly should face
MakeButterflyFaceProperDirectionAndAdjustAnimationSpeed(cParticle);
}
}
protected void ChangeDirectionRandomly(DefaultAnimatedTexturedQuadParticle cParticle, float fElapsedTimeInSeconds)
{
// If we should pick a new Direction (happens randomly) (-1 is specified when initializing new particles)
float fClamped = MathHelper.Clamp(fElapsedTimeInSeconds, -1f, 0.01f);
if (RandomNumber.NextFloat() < fClamped || fElapsedTimeInSeconds < 0)
{
// Calculate a new Velocity direction
cParticle.Velocity = new Vector3(RandomNumber.Next(-miButterflyMaxSpeed, miButterflyMaxSpeed),
RandomNumber.Next(-miButterflyMaxSpeed, miButterflyMaxSpeed),
RandomNumber.Next(-miButterflyMaxSpeed, miButterflyMaxSpeed));
// Calculate the new Direction the Butterfly should face
MakeButterflyFaceProperDirectionAndAdjustAnimationSpeed(cParticle);
}
}
public void InitializeParticleAnimated(DefaultAnimatedTexturedQuadParticle cParticle)
{
InitializeParticleUsingInitialProperties(cParticle);
cParticle.Animation.CopyFrom(mcAnimation);
ChangeDirectionRandomly(cParticle, -1);
}
