void Start()
{
color = color.SetRandomGrayColor(alpha);
ps = GetComponent <ParticleSystem>();
particles = new ParticleSystem.Particle[ps.main.maxParticles];
int partCount = ps.GetParticles(particles);
setParticleColors(partCount);
setParticleSizes(partCount);
var trails = ps.trails;
trails.enabled = true;
var psr = GetComponent <ParticleSystemRenderer>();
psr.trailMaterial = new Material(Shader.Find("Sprites/Default"));
}
