按下鼠标在屏幕内划线，绘制跟随鼠标的曲线

<span style="font-size:14px;">using UnityEngine;
using System;
using System.Collections;
using System.Collections.Generic;

public class Test : MonoBehaviour {

    //绘制线段的材质
    public Material material;//创建一个Material，拖拽到该参数上即可
    private List<Vector3> lineInfo;
    // Use this for initialization
    void Start()
    {
        //初始化鼠标线段链表
        lineInfo = new List<Vector3>();
    }

    // Update is called once per frame
    void Update()
    {
        //将每次鼠标改变的位置存储进链表
        lineInfo.Add(Input.mousePosition);
    }

    //此绘制方法由系统调用
    void OnPostRender()
    {
        if (!material)
        {
            Debug.Log("请给材质赋值");
            return;
        }

        //设置该材质通道，0为默认值
        material.SetPass(0);
        //设置绘制2D图像
        GL.LoadOrtho();
        //表示开始绘制，绘制累心改为线段
        GL.Begin(GL.LINES);
        //得到鼠标垫信息的总数量
        int size = lineInfo.Count;
        //遍历鼠标点的链表
        for (int i = 0; i < size - 1; i++)
        {
            Vector3 start = lineInfo[i];
            Vector3 end = lineInfo[i + 1];
            //绘制线段
            DrawLine(start.x, start.y, end.x, end.y);
        }
        GL.End();
    }

    void DrawLine(float x1, float y1, float x2, float y2)
    {
        //绘制线段，需要将屏幕中某个点的像素坐标除以屏幕宽或高
        GL.Vertex(new Vector3(x1 / Screen.width, y1 / Screen.height, 0));
        GL.Vertex(new Vector3(x2 / Screen.width, y2 / Screen.height, 0));
    }

}
</span>