using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(LineRenderer))]
public class TrailLine : MonoBehaviour
{
    public float pointSpacing = 0.1f; // 两个轨迹点之间的最小距离
    private LineRenderer lineRenderer;
    private List<Vector3> points = new List<Vector3>();

    private Vector3 lastPoint;

    void Start()
    {
        lineRenderer = GetComponent<LineRenderer>();
        lineRenderer.startWidth = 0.03f;
        lineRenderer.endWidth = 0.03f;
        lineRenderer.material = new Material(Shader.Find("Sprites/Default"));
        lineRenderer.startColor = Color.red;
        lineRenderer.endColor = Color.red;

        // 初始化第一个点
        points.Add(transform.position);
        lastPoint = transform.position;
    }

    void Update()
    {
        float distance = Vector3.Distance(transform.position, lastPoint);

        // 如果移动距离超过设定的间隔，就记录一个点
        if (distance >= pointSpacing)
        {
            points.Add(transform.position);
            lastPoint = transform.position;

            // 更新 LineRenderer 的点
            lineRenderer.positionCount = points.Count;
            lineRenderer.SetPositions(points.ToArray());
        }
    }
}