Create MeshCombineWizard.cs

Author: unitycoder

Assets/Scripts/Editor/Mesh/MeshCombineWizard.cs

@@ -0,0 +1,127 @@
+// from https://forum.unity.com/threads/mesh-combine-wizard-free-unity-tool-source-code.444483/#post-5575042
+
+using UnityEngine;
+using UnityEditor;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace UnityLibrary
+{
+  public class MeshCombineWizard : ScriptableWizard
+  {
+      public GameObject parentOfObjectsToCombine;
+
+      [MenuItem("E.S. Tools/Mesh Combine Wizard")]
+      static void CreateWizard()
+      {
+          ScriptableWizard.DisplayWizard<MeshCombineWizard>("Mesh Combine Wizard");
+      }
+
+      void OnWizardCreate()
+      {
+          if (parentOfObjectsToCombine == null) return;
+
+          Vector3 originalPosition = parentOfObjectsToCombine.transform.position;
+          parentOfObjectsToCombine.transform.position = Vector3.zero;
+
+          MeshFilter[] meshFilters = parentOfObjectsToCombine.GetComponentsInChildren<MeshFilter>();
+          Dictionary<Material, List<MeshFilter>> materialToMeshFilterList = new Dictionary<Material, List<MeshFilter>>();
+          List<GameObject> combinedObjects = new List<GameObject>();
+
+          for (int i = 0; i < meshFilters.Length; i++)
+          {
+              var materials = meshFilters[i].GetComponent<MeshRenderer>().sharedMaterials;
+              if (materials == null) continue;
+              if (materials.Length > 1)
+              {
+                  parentOfObjectsToCombine.transform.position = originalPosition;
+                  Debug.LogError("Objects with multiple materials on the same mesh are not supported. Create multiple meshes from this object's sub-meshes in an external 3D tool and assign separate materials to each.");
+                  return;
+              }
+              var material = materials[0];
+              if (materialToMeshFilterList.ContainsKey(material)) materialToMeshFilterList[material].Add(meshFilters[i]);
+              else materialToMeshFilterList.Add(material, new List<MeshFilter>() { meshFilters[i] });
+          }
+
+
+          // NC 03/2020 changes the loop to create meshes smaller than 695536 vertices
+          foreach (var entry in materialToMeshFilterList)
+          {
+              // get list of each meshes order by number of vertices
+              List<MeshFilter> meshesWithSameMaterial = entry.Value.OrderByDescending(mf => mf.sharedMesh.vertexCount).ToList();
+              // split into bins of 65536 vertices max
+              int nrMeshes = meshesWithSameMaterial.Count;
+              while (nrMeshes > 0)
+              {
+                  string materialName = entry.Key.ToString().Split(' ')[0];
+                  List<MeshFilter> meshBin = new List<MeshFilter>();
+                  meshBin.Add(meshesWithSameMaterial[0]);
+                  meshesWithSameMaterial.RemoveAt(0);
+                  nrMeshes--;
+                  // add meshes in bin until 65536 vertices is reached
+                  for (int i = 0; i < meshesWithSameMaterial.Count; i++)
+                  {
+                      if (meshBin.Sum(mf => mf.sharedMesh.vertexCount) + meshesWithSameMaterial[i].sharedMesh.vertexCount < 65536)
+                      {
+                          meshBin.Add(meshesWithSameMaterial[i]);
+                          meshesWithSameMaterial.RemoveAt(i);
+                          i--;
+                          nrMeshes--;
+                      }
+                  }
+
+                  // merge this bin
+                  CombineInstance[] combine = new CombineInstance[meshBin.Count];
+                  for (int i = 0; i < meshBin.Count; i++)
+                  {
+                      combine[i].mesh = meshBin[i].sharedMesh;
+                      combine[i].transform = meshBin[i].transform.localToWorldMatrix;
+                  }
+                  Mesh combinedMesh = new Mesh();
+                  combinedMesh.CombineMeshes(combine);
+
+                  // save the mesh
+                  materialName += "_" + combinedMesh.GetInstanceID();
+                  if (meshBin.Count > 1)
+                  {
+                      AssetDatabase.CreateAsset(combinedMesh, "Assets/CombinedMeshes_" + materialName + ".asset"); ;
+                  }
+
+                  // assign the mesh to a new go
+                  string goName = (materialToMeshFilterList.Count > 1) ? "CombinedMeshes_" + materialName : "CombinedMeshes_" + parentOfObjectsToCombine.name;
+                  GameObject combinedObject = new GameObject(goName);
+                  var filter = combinedObject.AddComponent<MeshFilter>();
+                  if (meshBin.Count > 1)
+                  {
+                      filter.sharedMesh = combinedMesh;
+                  }
+                  else
+                  {
+                      filter.sharedMesh = meshBin[0].sharedMesh; // the original mesh
+                  }
+                  var renderer = combinedObject.AddComponent<MeshRenderer>();
+                  renderer.sharedMaterial = entry.Key;
+                  combinedObjects.Add(combinedObject);
+              }
+          }
+
+          GameObject resultGO = null;
+          if (combinedObjects.Count > 1)
+          {
+              resultGO = new GameObject("CombinedMeshes_" + parentOfObjectsToCombine.name);
+              foreach (var combinedObject in combinedObjects) combinedObject.transform.parent = resultGO.transform;
+          }
+          else
+          {
+              resultGO = combinedObjects[0];
+          }
+
+          Object prefab = PrefabUtility.CreateEmptyPrefab("Assets/" + resultGO.name + ".prefab");
+          PrefabUtility.ReplacePrefab(resultGO, prefab, ReplacePrefabOptions.ConnectToPrefab);
+
+          parentOfObjectsToCombine.SetActive(false);
+          parentOfObjectsToCombine.transform.position = originalPosition;
+          resultGO.transform.position = originalPosition;
+      }
+  }
+}