private Particle newParticle(Vector2 pos, float angle, Vector2 sourceVelocity)
{
Particle particle = new Particle();
particle.Position = pos;
float directionAngle = (float)MathHelper.ToRadians((XnaHelper.RandomAngle(angle, _arc)));
float speed = applyVariance(_particleSpeed, _speedVariance);
particle.Velocity = speed * XnaHelper.VectorFromAngle(directionAngle);
particle.Scale = applyVariance(_particleScale, _scaleVariance);
particle.Angle = angle;
particle.LifeTime = TimeSpan.FromSeconds(applyVariance((float)_particleLife.TotalSeconds, _particleLifeVariance));
if (Reversed)
{
float secondsAlive = (float)particle.LifeTime.TotalSeconds;
//start at the end
particle.Position = particle.Position + particle.Velocity * secondsAlive;
//comment above and uncomment below for a cool effect (unintentional side effect while working on particles.
//not sure why it looks so awesome, but it does)
//particle.Position = particle.Position + particle.Velocity * secondsAlive * (1 - _particleDecelerationFactor);
//movce in reverse
particle.Velocity = Vector2.Negate(particle.Velocity);
//start at end scale
particle.Scale = _particleScale + _scaleRate * secondsAlive;
//start at end rotation
particle.Angle = _particleRotationSpeed * secondsAlive;
}
particle.Velocity += sourceVelocity;
return(particle);
}