毎日出題の４日目第三問 description: http://jigax.jp/unityunityとcを学ぶ問題004/ movie:https://vimeo.com/170791709

BounceBall.cs

public class BounceBall : MonoBehaviour {

	Material mat;
	enum State
	{
		red = 0,blue = 1,green = 2,free = 3
	}
	State state = State.red;
	void Start()
	{
		this.mat = GetComponent<Renderer>().material;
		this.mat.color = Color.red;
	}

	void Update()
	{
		if ( this.state == State.free )
		{
			this.mat.color = new Color(
				UnityEngine.Random.Range(0f, 1f),
				UnityEngine.Random.Range(0f, 1f),
				UnityEngine.Random.Range(0f, 1f)
			);
		}
	}
	void OnCollisionEnter( Collision col )
	{
		this.state = this.IncreaseState();
		switch ( this.state )
		{
			case State.red:
				this.mat.color = Color.red;
				break;
			case State.blue:
				this.mat.color = Color.blue;
				break;
			case State.green:
				this.mat.color = Color.green;
				break;
			default:
				break;
		}
	}
	State IncreaseState()
	{
		if ( System.Enum.GetValues(typeof(State)).Length - 1 <= (int)this.state )
		{
			return 0;
		}
		return this.state + 1;
	}
}