毎日出題の３日目第一問の答え

CreatePrimitiveByMouse.cs

public class CreatePrimitiveByMouse : MonoBehaviour {
	GameObject primitive = null;
	void Update () {

		if (Input.GetMouseButton(0))
		{
			// マウス位置から発生するRayを作成
			var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
			// 当たり確認オブジェクト
			RaycastHit hit;
			if (Physics.Raycast(ray, out hit, float.MaxValue))
			{
				if (primitive == null)
				{
					primitive = GameObject.CreatePrimitive(PrimitiveType.Cube);
					Destroy(primitive.GetComponent<Collider>());
				}
				primitive.SetActive(true);
				primitive.transform.position = hit.point;
			}

		}
		else
		if (Input.GetMouseButtonUp(0)) {
			if (primitive != null)
			{
				primitive.SetActive(false);
			}
		}

	}
}