ParticleSystem.EmitParams.velocity

Description

Override the velocity of particles this system emits.

Additional resources: ParticleSystem.Particle.velocity.

using UnityEngine;

// In this example we have a Particle System emitting aligned particles; we then emit and override the position and velocity every 2 seconds.
public class ExampleClass : MonoBehaviour
{
    private ParticleSystem system;

    void Start()
    {
        // A simple particle material with no texture.
        Material particleMaterial = new Material(Shader.Find("Particles/Standard Unlit"));

        // Create a Particle System.
        var go = new GameObject("Particle System");
        go.transform.Rotate(-90, 0, 0); // Rotate so the system emits upwards.
        system = go.AddComponent<ParticleSystem>();
        go.GetComponent<ParticleSystemRenderer>().material = particleMaterial;

        // Every 2 seconds we will emit.
        InvokeRepeating("DoEmit", 2.0f, 2.0f);
    }

    void DoEmit()
    {
        // Any parameters we assign in emitParams will override the current system's when we call Emit.
        // Here we will override the position and velocity. All other parameters will use the behavior defined in the Inspector.
        var emitParams = new ParticleSystem.EmitParams();
        emitParams.position = new Vector3(0.0f, 0.0f, 0.0f);
        emitParams.velocity = new Vector3(0.0f, 0.0f, -2.0f);
        system.Emit(emitParams, 1);
    }
}