Unity 使用LineRenderer 画箭头

using UnityEngine;
using System.Collections;

public class LineRendererScript : MonoBehaviour 
{
	[SerializeField]
	private LineRenderer BodyLineRenderer;
	[SerializeField]
	private LineRenderer HeadLineRenderer;

	private bool IsFinished = false;
	private bool IsReady = false;
	private Vector3 StartPos;
	private Vector3 EndPos;

	private float zDepth = 10f;
	private float headWidth = 0.4f;
	private float bodyWidth = 0.3f;

	void Awake()
	{
		if(BodyLineRenderer == null)
			BodyLineRenderer = GetComponent<LineRenderer>();
	}

	void Update()
	{
		if(IsFinished)
			return;

		if(Input.GetMouseButtonDown(0))
		{
			IsReady = true;
			StartPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
			StartPos.z = zDepth;
		}
		else if(Input.GetMouseButtonUp(0))
		{
			IsReady = false;
			IsFinished = true;
		}

		if(IsReady)
		{
			EndPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
			EndPos.z = zDepth;

			BodyLineRenderer.SetPosition(0,