Combine Meshes Creates Bad Geometry

Unity Engine
1

Using the combine meshes example from the docs is creating long triangles where they shouldn’t be.

Before combining.

1341×632 96.2 KB

After combining.

1341×632 109 KB

Here’s the code that combines the meshes

public static void Combine (GameObject go) {
        MeshFilter[] meshFilters = go.GetComponentsInChildren<MeshFilter>();
        CombineInstance[] combine = new CombineInstance[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.active = false;
            i++;
        }
        go.transform.GetComponent<MeshFilter>().mesh = new Mesh();
        go.transform.GetComponent<MeshFilter>().mesh.CombineMeshes(combine);
        go.active = true;
    }

Am I missing something? Does CombineMeshes not work?

2

So I know this is a couple years to late for you DanP, but if anyone else runs into this like I have, here is the issue:

The resulting mesh has too many verts.
I solved this by creating a List<CombineInstance[ ]>

public void CombineMeshesOfLikeMaterials()
    {
        foreach(GameObject parent in shipPartParentsOfUniqueMaterialColors)
        {
            MeshFilter[] meshFilters = parent.GetComponentsInChildren<MeshFilter>();
            List<CombineInstance> combineSubMeshes = new List<CombineInstance>();
            List<CombineInstance[]> combineList = new List<CombineInstance[]>();
            int currentMeshVertCount = 0;

            for (int i = 0; i < meshFilters.Length; i++)
            {
                if (currentMeshVertCount + meshFilters[i].sharedMesh.vertexCount >= 65000)
                {
                    combineList.Add(combineSubMeshes.ToArray());
                    combineSubMeshes = new List<CombineInstance>();
                    currentMeshVertCount = 0;
                }

                currentMeshVertCount += meshFilters[i].sharedMesh.vertexCount;


                CombineInstance combine = new CombineInstance();
                combine.mesh = meshFilters[i].sharedMesh;
                combine.transform = meshFilters[i].transform.localToWorldMatrix;
                combineSubMeshes.Add(combine);
               
                Object.Destroy(meshFilters[i].gameObject);
            }

            // Add last submesh that was under 65000 verts
            combineList.Add(combineSubMeshes.ToArray());

            for (int i = 0; i < combineList.Count; i++)
            {
                GameObject shipPartParent = new GameObject(parent.name + "_" + i.ToString());

                MeshFilter parentMeshFilter = shipPartParent.AddComponent<MeshFilter>() as MeshFilter;
                parentMeshFilter.mesh = new Mesh();
                parentMeshFilter.mesh.CombineMeshes(combineList[i]);
                parentMeshFilter.transform.position = Vector3.zero;
                shipPartParent.SetActive(true);

                MeshRenderer parentRenderer = shipPartParent.AddComponent<MeshRenderer>() as MeshRenderer;
                Material parentMat = Object.Instantiate((Material)Resources.Load("SvgDeckMaterial", typeof(Material)));
                parentMat.color = parent.GetComponent<MeshRenderer>().material.color;//partColor;
                parentRenderer.material = parentMat;

                shipPartParent.transform.SetParent(parent.transform);
            }
        }
    }
2 Likes
3

In 2021 it can be solved by increasing the indexFormat:

        Mesh finalMesh = new Mesh();
        finalMesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;