UnityEngine.ParticleSystem.SetParticles C# (CSharp) Method

        public extern void SetParticles(Particle[] particles, int size);
        [MethodImpl(MethodImplOptions.InternalCall), WrapperlessIcall]

    void Start()
    {
        particleSystem = gameObject.GetComponent<ParticleSystem>();

        const int maxParticle = 1000;
        particleSystem.maxParticles = maxParticle;
        particles = new ParticleSystem.Particle[maxParticle];
        particleData = new ParticleData[maxParticle];
        particleSystem.Emit(maxParticle);
        particleSystem.GetParticles(particles);

        for (int i = 0; i < maxParticle; i++)
        {
            particles[i].position = Vector3.zero;
            particles[i].velocity = Vector3.zero;
            particles[i].size = 0.1f;

            float rotateX = Random.value * 360;
            float rotateY = Random.value * 180;
            float rotateZ = Random.value * 360;

            Quaternion q = new Quaternion();
            q.eulerAngles = new Vector3(rotateX, rotateY, rotateZ);
            particleData[i].direction = q * Vector3.forward;
            particleData[i].speed = 1;
            particleData[i].cos = i / ((float)maxParticle / 10);
        }

        particleSystem.SetParticles(particles, maxParticle);
    }