獲取場景 Mesh 數據開發指南

using System.Collections.Generic;
using LCCCore;
using UnityEngine;
using UnityEngine.Rendering;

public class Meshes : MonoBehaviour
{
    public LCCManager m_manager;
    public string m_FilePath;
    private LCCCore.Renderer m_renderer;
    private bool m_isLoaded = false;
    private Camera m_camera;

    private const string kContainerName = "LCCVisualizedMeshes";

    void Start()
    {
        m_camera = Camera.main;
        m_isLoaded = false;
        m_manager.SetPlatformType(PlatformType.PC);

        m_renderer = m_manager.GetRender(this.transform);
        m_renderer.Load(m_FilePath,
            p => Debug.Log($"[Meshes] load progress: {p:P1}"),
            () =>
            {
                Debug.Log($"[Meshes] file loaded: {m_FilePath}");
                m_isLoaded = true;
                m_manager.SetAutoFov(false);
            },
            e => Debug.LogError($"[Meshes] file load error: {e}")
        );
    }

    public void onGetAllMeshes()
    {
        if (!m_isLoaded || m_renderer == null)
        {
            Debug.LogWarning("[Meshes] 數據尚未加載完成，無法獲取 Mesh。");
            return;
        }

        var meshes = m_renderer.GetMeshes();
        if (meshes == null || meshes.Count == 0)
        {
            Debug.LogWarning("[Meshes] 未獲取到 Mesh（數據可能不含碰撞體）。");
            return;
        }

        VisualizeMeshes(meshes);
    }

    private void VisualizeMeshes(List<LCCMeshBlock> meshes)
    {
        // 清理上一次的可視化結果，避免重複堆積
        Transform root = m_renderer.Transform;
        Transform old = root.Find(kContainerName);
        if (old != null) Destroy(old.gameObject);

        var container = new GameObject(kContainerName).transform;
        container.SetParent(root, false);

        Material material = CreateVisualMaterial();

        for (int i = 0; i < meshes.Count; i++)
        {
            LCCMeshBlock block = meshes[i];
            if (block.vertices == null || block.vertices.Length == 0) continue;
            if (block.triangles == null || block.triangles.Length < 3) continue;

            var go = new GameObject(string.IsNullOrEmpty(block.id) ? $"MeshBlock_{i}" : block.id);
            go.transform.SetParent(container, false);

            var mesh = new Mesh { name = go.name };
            // 單塊頂點數可能超過 65535，必須使用 32 位索引，否則幾何錯亂
            mesh.indexFormat = IndexFormat.UInt32;
            mesh.vertices = block.vertices;
            mesh.triangles = block.triangles;
            mesh.RecalculateNormals();
            mesh.RecalculateBounds();

            var mf = go.AddComponent<MeshFilter>();
            mf.sharedMesh = mesh;

            var mr = go.AddComponent<MeshRenderer>();
            mr.sharedMaterial = material;
        }

        Debug.Log($"[Meshes] 已為 {meshes.Count} 個 Mesh 分塊創建 GameObject 並可視化。");
    }

    private Material CreateVisualMaterial()
    {
        Shader shader = Shader.Find("Universal Render Pipeline/Lit")
            ?? Shader.Find("Standard")
            ?? Shader.Find("Diffuse");
        if (shader == null) return null;

        var mat = new Material(shader) { color = new Color(0.7f, 0.7f, 0.7f, 1f) };
        // 碰撞網格三角形繞序不保證一致，關閉背面剔除以完整顯示
        mat.SetFloat("_Cull", (float)CullMode.Off);
        return mat;
    }
}

public void onRequireMeshes()
{
    if (!m_isLoaded || m_renderer == null)
    {
        Debug.LogWarning("[Meshes] 數據尚未加載完成，無法獲取 Mesh。");
        return;
    }

    // 1. 零 I/O 讀取全部分塊元信息，按相機到 BBOX 表面距離篩選 100 m 內的分塊
    var infos = m_renderer.GetMeshBlockInfos();
    if (infos == null || infos.Count == 0)
    {
        Debug.LogWarning("[Meshes] 未獲取到 Mesh 信息（數據可能不含碰撞體）。");
        return;
    }

    Vector3 camPos = m_camera.transform.position;
    var ids = new List<string>();
    foreach (var info in infos)
    {
        // 相機位於 BBOX 內部時 ClosestPoint 返回相機自身、距離為 0，同樣會被選中
        if (calculateMinDistanceToAABB(info.boundsWorld, camPos) < 100f)
            ids.Add(info.id);
    }

    if (ids.Count == 0)
    {
        Debug.LogWarning("[Meshes] 相機周圍 100m 內沒有 Mesh 分塊。");
        return;
    }

    // 2. 按 id 只讀取篩選出的分塊並可視化
    var meshes = m_renderer.GetMeshes(ids);
    if (meshes == null || meshes.Count == 0)
    {
        Debug.LogWarning("[Meshes] 按 id 獲取 Mesh 失敗。");
        return;
    }

    VisualizeMeshes(meshes);
    Debug.Log($"[Meshes] 相機周圍 100m 內選中 {ids.Count} 個分塊，可視化 {meshes.Count} 個。");
}

// 計算點到 AABB 表面的最近距離（點位於 AABB 內部時返回 0）
private static float calculateMinDistanceToAABB(Bounds _aabb, Vector3 _point)
{
    Vector3 p = _aabb.ClosestPoint(_point);
    return Vector3.Distance(p, _point);
}

// 返回值：List<LCCMeshBlockInfo> → 碰撞 Mesh 分塊元信息；無 Mesh 或不可用時返回 null
public List<LCCMeshBlockInfo> GetMeshBlockInfos()

var infos = renderer.GetMeshBlockInfos();
foreach (var info in infos)
{
    Debug.Log($"{info.id}: verts={info.vertexCount}, faces={info.faceCount}, bbox={info.boundsWorld.size}");
}

// 返回值：List<LCCMeshBlock> → 全部碰撞 Mesh 幾何數據；不可用時返回 null
public List<LCCMeshBlock> GetMeshes()

var meshes = renderer.GetMeshes();
foreach (var block in meshes)
{
    // block.vertices / block.triangles 在物體本地座標系
}

// 返回值：List<LCCMeshBlock> → 指定 id 的碰撞 Mesh 幾何數據；無命中時返回 null
public List<LCCMeshBlock> GetMeshes(IEnumerable<string> _ids)

var ids = new List<string> { "block-0", "block-3" };
var meshes = renderer.GetMeshes(ids);

public struct LCCMeshBlockInfo {
    public string id;           // 節點 id，與 LCCMeshBlock.id 對應
    public Bounds boundsWorld;  // 世界空間 AABB，用於挑選 id
    public Bounds boundsLocal;  // 本地空間 AABB
    public int vertexCount;     // 頂點數
    public int faceCount;       // 面數
}

public struct LCCMeshBlock {
    public string id;           // 節點 id
    public Vector3[] vertices;  // 頂點，本地座標系
    public int[] triangles;     // 三角形索引，每 3 個一組
    public Bounds boundsLocal;  // 與 vertices 同空間的包圍盒
}