UnityのRigidbodyでdragをいじって水中を表現

WaterChecker.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class WaterChecker : MonoBehaviour {

	Rigidbody rb;
	string waterTag = "Water";
	public float waterDrag = 3.0f;
	float defaultDrag = 0.0f;

	void Start(){
		rb = gameObject.GetComponent<Rigidbody>();
		defaultDrag = rb.drag;
	}

	void OnTriggerEnter(Collider other){
		if (other.gameObject.tag == waterTag){
			// 水の中の抵抗をセット
			rb.drag = waterDrag;
		}
	}

	void OnTriggerExit(Collider other){
		if (other.gameObject.tag == waterTag){
			// 通常の抵抗をセット
			rb.drag = defaultDrag;
		}
	}
}