initParticle method
Implementation
@override
void initParticle(Particle p) {
initPosition(p);
initRadius(p);
final double deltaSpeed = (options.spawnMaxSpeed - options.spawnMinSpeed);
double speed = random.nextDouble() * deltaSpeed + options.spawnMinSpeed;
initDirection(p, speed);
final double deltaOpacity = (options.maxOpacity - options.minOpacity);
p.alpha = options.spawnOpacity;
p.targetAlpha = random.nextDouble() * deltaOpacity + options.minOpacity;
}