using UnityEngine;
using System.Collections.Generic;

[ExecuteAlways] // 允许在编辑器非运行状态下预览效果
public class HeatMapEmitter : MonoBehaviour
{
    [Header("热源列表")]
    public List<Transform> heatSources = new List<Transform>(); // 拖入多个热源物体

    [Header("热力设置")]
    public float heatRadius = 5f;
    public AnimationCurve heatFalloff = AnimationCurve.EaseInOut(0, 1, 1, 0);

    [Header("颜色设置")]
    public Color coldColor = new Color(0, 0, 0.5f, 1); // 深蓝
    public Color hotColor = Color.red;

    private MeshFilter meshFilter;
    private Mesh mesh;
    private Vector3[] baseVertices;
    private Color[] vertexColors;

    void OnEnable()
    {
        InitializeMesh();
    }

    [ContextMenu("Refresh Mesh Data")]
    void InitializeMesh()
    {
        meshFilter = GetComponent<MeshFilter>();
        if (meshFilter == null || meshFilter.sharedMesh == null) return;

        // 注意：在编辑器模式下建议操作 sharedMesh
        mesh = meshFilter.sharedMesh;
        baseVertices = mesh.vertices;
        vertexColors = new Color[baseVertices.Length];

        // 初始化颜色
        UpdateHeatMap();
    }

    void Update()
    {
        if (baseVertices == null || heatSources == null || heatSources.Count == 0) return;
        UpdateHeatMap();
    }

    void UpdateHeatMap()
    {
        Matrix4x4 localToWorld = transform.localToWorldMatrix;

        for (int i = 0; i < baseVertices.Length; i++)
        {
            Vector3 vertexWorldPos = localToWorld.MultiplyPoint3x4(baseVertices[i]);
            float maxHeat = 0f;

            // --- 核心逻辑：遍历所有热源，取影响最大的那个 ---
            foreach (var source in heatSources)
            {
                if (source == null) continue;

                float distance = Vector3.Distance(vertexWorldPos, source.position);
                float t = Mathf.Clamp01(distance / heatRadius);
                float currentHeat = heatFalloff.Evaluate(t);

                // 取所有热源中对该点影响最大的热度
                if (currentHeat > maxHeat)
                {
                    maxHeat = currentHeat;
                }
            }

            // 映射颜色
            vertexColors[i] = Color.Lerp(coldColor, hotColor, maxHeat);
        }

        mesh.colors = vertexColors;
    }

    void OnDrawGizmosSelected()
    {
        // 选中物体时画出所有热源范围
        Gizmos.color = new Color(1, 1, 0, 0.2f);
        foreach (var source in heatSources)
        {
            if (source != null) Gizmos.DrawWireSphere(source.position, heatRadius);
        }
    }
}