mesh合并

mesh合并

mesh 合并的过程中，往往会忽略掉submesh的，如果submesh 长度大于1，从而导致顶点 丢失

官方案列：就会导致submesh 丢失

https://docs.unity3d.com/cn/2022.3/ScriptReference/Mesh.CombineMeshes.html

using UnityEngine;
using System.Collections;  
  
// Copy meshes from children into the parent's [Mesh](https://docs.unity3d.com/cn/2022.3/ScriptReference/Mesh.html).
// [CombineInstance](https://docs.unity3d.com/cn/2022.3/ScriptReference/CombineInstance.html) stores the list of meshes.  These are combined
// and assigned to the attached [Mesh](https://docs.unity3d.com/cn/2022.3/ScriptReference/Mesh.html).  
  
[[RequireComponent](https://docs.unity3d.com/cn/2022.3/ScriptReference/RequireComponent.html)(typeof([MeshFilter](https://docs.unity3d.com/cn/2022.3/ScriptReference/MeshFilter.html)))]
[[RequireComponent](https://docs.unity3d.com/cn/2022.3/ScriptReference/RequireComponent.html)(typeof([MeshRenderer](https://docs.unity3d.com/cn/2022.3/ScriptReference/MeshRenderer.html)))]
public class ExampleClass : [MonoBehaviour](https://docs.unity3d.com/cn/2022.3/ScriptReference/MonoBehaviour.html)
{
    void Start()
    {
        [MeshFilter](https://docs.unity3d.com/cn/2022.3/ScriptReference/MeshFilter.html)[] meshFilters = GetComponentsInChildren<[MeshFilter](https://docs.unity3d.com/cn/2022.3/ScriptReference/MeshFilter.html)>();
        [CombineInstance](https://docs.unity3d.com/cn/2022.3/ScriptReference/CombineInstance.html)[] combine = new [CombineInstance](https://docs.unity3d.com/cn/2022.3/ScriptReference/CombineInstance.html)[meshFilters.Length];  
  
        int i = 0;
        while (i < meshFilters.Length)
        {
            combine[i].mesh = meshFilters[i].sharedMesh;
            combine[i].transform = meshFilters[i].transform.localToWorldMatrix;
            meshFilters[i].gameObject.SetActive(false);  
  
            i++;
        }  
  
        [Mesh](https://docs.unity3d.com/cn/2022.3/ScriptReference/Mesh.html) mesh = new [Mesh](https://docs.unity3d.com/cn/2022.3/ScriptReference/Mesh.html)();
        mesh.CombineMeshes(combine);
        transform.GetComponent<[MeshFilter](https://docs.unity3d.com/cn/2022.3/ScriptReference/MeshFilter.html)>().sharedMesh = mesh;
        transform.gameObject.SetActive(true);
    }
}

案列

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
using UnityEngine;
using UnityEngine.Rendering;

public class MeshCombiner : MonoBehaviour
{
    void Start()
    {
        MeshFilter[] meshFilters = GetComponentsInChildren<MeshFilter>();
        List<CombineInstance> combine = new List<CombineInstance>();
        List<Material> materials = new List<Material>();

        for (int i = 0; i < meshFilters.Length; i++)
        {
            MeshRenderer renderer = meshFilters[i].GetComponent<MeshRenderer>();
			//submesh 合并
			//如果忽略了mesh.subMeshCount，subMeshIndex只会为0，可导致其余的submesh丢失
            Mesh mesh = meshFilters[i].sharedMesh;
            for (int j = 0; j < mesh.subMeshCount; j++)
            {
                var newCombineInstance = new CombineInstance();
                newCombineInstance.mesh = meshFilters[i].sharedMesh;
                newCombineInstance.transform = meshFilters[i].transform.localToWorldMatrix;
                newCombineInstance.subMeshIndex = j;
                combine.Add(newCombineInstance);
            }


            materials.AddRange(renderer.sharedMaterials);
            meshFilters[i].gameObject.SetActive(false);
        }

        Mesh combinedMesh = new Mesh();
        combinedMesh.indexFormat = IndexFormat.UInt32;
        combinedMesh.CombineMeshes(combine.ToArray(), true, false); // 设置为true以保留子网格信息

        MeshFilter meshFilter = gameObject.AddComponent<MeshFilter>();

        meshFilter.mesh = combinedMesh;

        MeshRenderer meshRenderer = gameObject.AddComponent<MeshRenderer>();
        meshRenderer.materials = materials.ToArray();
		｝
}