protected BaseSpriteParticle NewParticle(
Vector3 pos,
Vector3 velocity,
float lifeTime,
Vector4 color,
float maxRotation,
int numTiles)
{
BaseSpriteParticle part = null;
if (particleList.Count < MaxSprites)
{
if (unused.Count > 0)
{
part = unused[unused.Count - 1];
unused.RemoveAt(unused.Count - 1);
part.Set(pos, velocity, lifeTime, color, maxRotation, numTiles);
}
else
{
part = new BaseSpriteParticle();
part.Set(pos, velocity, lifeTime, color, maxRotation, numTiles);
}
}
return(part);
}
public override void UpdateParticles(float dt)
{
// Let the particles keep up with us as we move
Vector3 advance = (Position - PreviousPosition) * KeepUp;
for (int i = 0; i < particleList.Count;)
{
BaseSpriteParticle particle = (BaseSpriteParticle)particleList[i];
particle.age += dt;
Debug.Assert(particle.age >= 0.0f);
float t = particle.age / particle.lifetime;
if (t > 1.0f)
{
// Dead particle.
ReleaseParticle(i);
}
else
{
particle.radius = MyMath.Lerp(startRadius, endRadius, t) * scale;
particle.alpha = MyMath.Lerp(startAlpha, endAlpha, t);
particle.rotation += particle.deltaRotation * dt;
// Change the linear fade to a curve.
particle.alpha *= particle.alpha;
// Add in gravity effect.
if (NonZeroGravity)
{
particle.velocity += Gravity * dt;
float speed2 = particle.velocity.LengthSquared();
if (speed2 > MaxSpeed * MaxSpeed)
{
particle.velocity.Normalize();
particle.velocity *= MaxSpeed;
}
}
particle.position += advance;
particle.position += particle.velocity * dt;
// Now make the spin about the source
Vector2 fromCenter = new Vector2(particle.position.X - Position.X, particle.position.Y - Position.Y);
fromCenter.Normalize();
double theta = dt * wreathRate;
float sinTheta = (float)Math.Sin(theta);
float cosTheta = (float)Math.Cos(theta);
Vector2 delPos = scale * wreathRadius * ((float)theta)
* (sinTheta * fromCenter
+ cosTheta * new Vector2(fromCenter.Y, -fromCenter.X));
particle.position.X += delPos.X;
particle.position.Y += delPos.Y;
i++;
}
} // end loop update particles.
}
} // end of BaseSpriteEmitter Update()
private void UpdateVerts()
{
for (int i = 0; i < particleList.Count; i++)
{
BaseSpriteParticle particle = (BaseSpriteParticle)particleList[particleList.Count - i - 1];
Vector3 newState = new Vector3(particle.rotation, particle.radius, particle.alpha);
for (int j = 0; j < 4; j++)
{
localVerts[i * 4 + j].position = particle.position;
localVerts[i * 4 + j].texCoord.Z = particle.tile;
localVerts[i * 4 + j].state = newState;
}
}
}
} // end of c'tor
protected override void Emit(float dt)
{
if (emitting && manager.AllowEmission())
{
// Adjust emission rate according to active particle count
float adjustedEmissionRate = manager.AdjustEmissionRate(emissionRate);
if (LinearEmission)
{
Vector3 deltaPosition = position - PreviousPosition;
float dist = deltaPosition.Length();
partial += dist * adjustedEmissionRate;
}
else
{
partial += dt * adjustedEmissionRate;
}
// Emit as many particles as needed this
// frame to keep up with the emission rate.
while (partial >= 1.0f)
{
if (particleList.Count < maxSprites)
{
// Pick a random position somewhere along the path covered this frame.
Vector3 pos = position - (position - PreviousPosition) * (float)rnd.NextDouble();
if (PositionJitter > 0.0f)
{
pos += PositionJitter * new Vector3((float)rnd.NextDouble() - (float)rnd.NextDouble(), (float)rnd.NextDouble() - (float)rnd.NextDouble(), (float)rnd.NextDouble() - (float)rnd.NextDouble());
}
double rads = rnd.NextDouble() * MathHelper.TwoPi;
Vector3 radial = scale * new Vector3((float)Math.Cos(rads), (float)Math.Sin(rads), 0.0f)
* (wreathRadius + RadialJitter * ((float)rnd.NextDouble() * 2.0f - 1.0f));
pos += radial;
// adjust lifetime according to active particle count
Vector2 adjLifeTime = manager.AdjustLifetime(minLifetime, maxLifetime);
float lifetime = adjLifeTime.X + (float)rnd.NextDouble() * (adjLifeTime.Y - adjLifeTime.X);
BaseSpriteParticle particle = NewParticle(pos, initParticleVelocity, lifetime, color, maxRotationRate, NumTiles);
particleList.Add(particle);
}
partial -= 1.0f;
}
}
PreviousPosition = position;
}
public virtual void UpdateParticles(float dt)
{
for (int i = 0; i < particleList.Count;)
{
BaseSpriteParticle particle = (BaseSpriteParticle)particleList[i];
particle.age += dt;
Debug.Assert(particle.age >= 0.0f);
float t = particle.age / particle.lifetime;
if (t > 1.0f)
{
// Dead particle.
ReleaseParticle(i);
}
else
{
particle.radius = MyMath.Lerp(startRadius, endRadius, t) * scale;
particle.alpha = MyMath.Lerp(startAlpha, endAlpha, t);
particle.rotation += particle.deltaRotation * dt;
// Change the linear fade to a curve.
particle.alpha *= particle.alpha;
// Add in gravity effect.
if (NonZeroGravity)
{
particle.velocity += Gravity * dt;
float speed2 = particle.velocity.LengthSquared();
if (speed2 > MaxSpeed * MaxSpeed)
{
particle.velocity.Normalize();
particle.velocity *= MaxSpeed;
}
}
particle.position += particle.velocity * dt;
i++;
}
} // end loop update particles.
}
} // end of c'tor
// Cut and pasted from BaseSpriteEmitter, just to override
// how the position is computed. Might like to refactor the
// Update into common particle tasks (spawn, kill, move, etc.)
public override void Update(Camera camera)
{
if (Active)
{
// Emit new particles if needed.
float dt = Time.GameTimeFrameSeconds;
dt = MathHelper.Clamp(dt, 0.0f, 1.0f); // Limit to reasonable values.
Position += Velocity * dt;
if (Emitting)
{
if (LinearEmission)
{
Vector3 deltaPosition = Position - PreviousPosition;
float dist = deltaPosition.Length();
partial += dist * EmissionRate;
}
else
{
partial += dt * EmissionRate;
}
// Emit as many particles as needed this
// frame to keep up with the emission rate.
while (partial >= 1.0f)
{
if (particleList.Count < MaxSprites)
{
// Pick a random position on the sphere.
Vector3 rndVec = new Vector3((float)(rnd.NextDouble() - rnd.NextDouble()),
(float)(rnd.NextDouble() - rnd.NextDouble()),
(float)(rnd.NextDouble() - rnd.NextDouble()));
rndVec.Normalize();
rndVec *= targetRadius;
Vector3 pos = Position + rndVec;
// Pick a random position somewhere along the path covered this frame.
if (PositionJitter > 0.0f)
{
pos += PositionJitter * new Vector3((float)rnd.NextDouble() - (float)rnd.NextDouble(), (float)rnd.NextDouble() - (float)rnd.NextDouble(), (float)rnd.NextDouble() - (float)rnd.NextDouble());
}
float lifetime = MinLifetime + (float)rnd.NextDouble() * (MaxLifetime - MinLifetime);
BaseSpriteParticle particle = new BaseSpriteParticle(pos, lifetime, Color, MaxRotationRate, NumTiles);
particleList.Add(particle);
}
partial -= 1.0f;
}
}
// Update the previous position to match the current one for the next frame.
ResetPreviousPosition();
// Update any existing particles. For more heavyweight particles we could
// have an Update call per particle. These are lightweight enough that we
// can just update them directly.
for (int i = 0; i < particleList.Count;)
{
BaseSpriteParticle particle = (BaseSpriteParticle)particleList[i];
particle.age += dt;
Debug.Assert(particle.age >= 0.0f);
float t = particle.age / particle.lifetime;
if (t > 1.0f)
{
// Dead particle.
particleList.RemoveAt(i);
}
else
{
particle.radius = MyMath.Lerp(StartRadius, EndRadius, t);
particle.alpha = MyMath.Lerp(StartAlpha, EndAlpha, t);
particle.rotation += particle.deltaRotation * dt;
// Change the linear fade to a curve.
particle.alpha *= particle.alpha;
// Add in gravity effect.
if (NonZeroGravity)
{
particle.velocity += Gravity * dt;
float speed2 = particle.velocity.LengthSquared();
if (speed2 > MaxSpeed * MaxSpeed)
{
particle.velocity.Normalize();
particle.velocity *= MaxSpeed;
}
}
particle.position += particle.velocity * dt;
i++;
}
} // end loop update particles.
// Now that we've updated all the particles, create/update the vertex buffer.
UpdateVerts();
// See if we've died.
if (Dying && particleList.Count == 0)
{
Active = false;
RemoveFromManager();
}
} // end of if active
} // end Update
