LineRenderer实现一个画线组件

using System;
using UnityEngine;

class UILine
{
    GameObject targetObj;
    LineRenderer lineRenderer;      //LineRenderer渲染出的线段的两个端点是3D世界中的点
    int index = 0;
    int poinCount = 0;  //线段的端点数
    Vector3 position;

    public void Start(GameObject go, Color beginColor, Color endColor, float begineWidth, float endWidth)
    {
        targetObj = go;
        if (null != targetObj)
        {
            targetObj.SetActive(true);
            lineRenderer = targetObj.GetComponent<LineRenderer>();

            if (null == lineRenderer)
                lineRenderer = targetObj.AddComponent<LineRenderer>();
        }

        if (null != lineRenderer)
        {
            //颜色
            lineRenderer.startColor = beginColor;
            lineRenderer.endColor = endColor;

            //宽度
            lineRenderer.startWidth = begineWidth;
            lineRenderer.endWidth = endWidth;
        }

        index = poinCount = 0;
    }

    public void Update()
    {
        if (Input.GetMouseButton(0))
        {
            //屏幕坐标转换为世界坐标
            position = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, 1.0f));
            //端点数+1
            poinCount++;
            //设置线段的端点数
            lineRenderer.positionCount = poinCount;

            //连续绘制线段
            while (index < poinCount)
            {
                //两点确定一条直线，所以我们依次绘制点就可以形成线段了
                lineRenderer.SetPosition(index, position);
                index++;
            }
        }
    }

    public static UILine BeginLine(GameObject go, Color beginColor, Color endColor, float beginWidth, float endWidth)
    {
        UILine line = new UILine();
        line.Start(go, beginColor, endColor, beginWidth, endWidth);
        return line;
    }
}