updateParticles method
void
updateParticles()
Implementation
void updateParticles() {
for (int i = 0; i < particles.length; i++) {
final particle = particles[i];
if (particle.life <= 0.1) {
particles[i] = _randomParticle(particle.rect);
} else {
particles[i] = particle.moveToRandomAngle();
}
}
}