ParticleSystem.LifetimeByEmitterSpeedModule.curve

Description

Use this curve to define which value to multiply the start lifetime of a particle with, based on the speed of the emitter when the particle is spawned.

Note that you should set this curve to ParticleSystemCurveMode.Curve or ParticleSystemCurveMode.TwoCurves in order to provide any value, as setting it to ParticleSystemCurveMode.Constant or ParticleSystemCurveMode.TwoConstants doesn't do anything that couldn't also be done without using this module, simply by using ParticleSystem.MainModule.startLifetime alone.

Additional resources: MinMaxCurve.

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(ParticleSystem))]
public class ExampleClass : MonoBehaviour
{
    private ParticleSystem ps;
    public bool moduleEnabled = true;
    public float maxSpeed = 5.0f;
    public AnimationCurve curve = AnimationCurve.EaseInOut(0.0f, 1.0f, 1.0f, 0.2f);

    void Start()
    {
        ps = GetComponent<ParticleSystem>();

        var mainModule = ps.main;
        mainModule.startLifetime = 1.0f;

        // make particles less random to more clearly see effect of lifetime.
        var shapeModule = ps.shape;
        shapeModule.radius = 0.1f;
        shapeModule.angle = 1.0f;

        var main = ps.main;
        main.simulationSpace = ParticleSystemSimulationSpace.World;

        // add a sphere so we can see our transform position as it moves
        var sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
        sphere.transform.parent = ps.transform;
    }

    void Update()
    {
        var lifetimeByEmitterSpeed = ps.lifetimeByEmitterSpeed;
        lifetimeByEmitterSpeed.enabled = moduleEnabled;
        lifetimeByEmitterSpeed.range = new Vector2(0, maxSpeed);
        lifetimeByEmitterSpeed.curve = new ParticleSystem.MinMaxCurve(1f, curve);

        ps.transform.position = new Vector3(Mathf.Sin(Time.time * 2.0f) * 4.0f, 0.0f, 0.0f);
    }

    void OnGUI()
    {
        moduleEnabled = GUI.Toggle(new Rect(25, 45, 100, 30), moduleEnabled, "Enabled");
        maxSpeed = GUI.HorizontalSlider(new Rect(25, 85, 100, 30), maxSpeed, 0.0f, 10.0f);
    }
}