访问粒子系统的生命周期速度模块。
不需要将粒子系统模块重新分配回系统；它们是接口而不是独立的对象。
using UnityEngine;
using System.Collections;
public class ExampleClass : MonoBehaviour {
void Start() {
ParticleSystem ps = GetComponent<ParticleSystem>();
var vel = ps.velocityOverLifetime;
vel.enabled = true;
vel.space = ParticleSystemSimulationSpace.Local;
AnimationCurve curve = new AnimationCurve();
curve.AddKey(0.0f, 1.0f);
curve.AddKey(1.0f, 0.0f);
vel.x = new ParticleSystem.MinMaxCurve(10.0f, curve);
}
}