Input.mousePosition 鼠标位置

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
	public GameObject particle;
	void Update() {
		if (Input.GetButtonDown("Fire1")) {
			Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
			if (Physics.Raycast(ray))
				Instantiate(particle, transform.position, transform.rotation);

		}
	}
}

var particle : GameObject;
function Update () {
	if (Input.GetButtonDown ("Fire1")) {
		// Construct a ray from the current mouse coordinates
		// 从当前鼠标坐标创建一条射线
		var ray : Ray = Camera.main.ScreenPointToRay (Input.mousePosition);
		if (Physics.Raycast (ray)) {
			// Create a particle if hit
			//如果检测到碰撞就创建一个粒子
			Instantiate (particle, transform.position, transform.rotation);
		}
	}
}