Rigidbody.useGravity 使用重力

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	void OnTriggerEnter(Collider other) {
	if (other.attachedRigidbody)
		other.attachedRigidbody.useGravity = false;

	}
	public void Awake() {
		collider.isTrigger = true;
	}
}

// Disables gravity on all rigid bodies entering this collider.
//当所有刚体进入这个碰撞器，禁用重力

function OnTriggerEnter (other : Collider) {
	if (other.attachedRigidbody) {
		other.attachedRigidbody.useGravity = false;
	}
}
// Turn this collider into a trigger on startup
//启动时把碰撞器变为触发器
collider.isTrigger = true;