public ParticleManager()
{
particle_array = new Particle[NUM_PARTICLES];
particle_pool = new Queue<Particle>(NUM_PARTICLES);
for (int i = 0; i < particle_array.Length; i++)
{
Particle particle = new Particle();
particle_array[i] = particle;
particle_pool.Enqueue(particle);
particle.in_pool = true;
particle.is_alive = false;
}
}