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unity手动合批

  • Conerlius
  • Dec 29, 2019
  • 0 views

背景

unity的静态合批在特定的情况下不能有效地合批，但是在scene的场景中缺有大量的静态物体！

技术原理

通过代码手动合批，生成一个个合并后的mesh和纹理材质，然后替换场景中原有的物体！

具体

unity本身也提供了相应的api给我们处理,在说到实现前，需要先说明一下合批的一些前提条件：

前提

  • 材质（Material）：材质球要相同，如果材质球不同，unity则无法进行静态合批！
  • 静态（static）： 必须是静态的对象！

png

CombineInstance

Struct used to describe meshes to be combined using Mesh.CombineMeshes.

用来描绘网格合并的结构,主要是为了使用Mesh.CombineMeshes

name des
mesh 合并的网格
subMeshIndex 子网格索引
transform 合并之前，网格变换的矩阵

CombineMeshes

这里就不细说了，代码里有注释了！

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEngine.SceneManagement;

public class CombineDemo
{
	[MenuItem("Tools/Combine Scene Static Mesh")]
	static void CombineInstance()
	{
		List<GameObject> rootGameObjects = new List<GameObject>();
		if (Selection.gameObjects != null && Selection.gameObjects.Length!=0)
		{
			foreach (var gameObject in Selection.gameObjects)
			{
				rootGameObjects.Add(gameObject);
			}
		}
		else
		{
			var editorScene = SceneManager.GetActiveScene();
			editorScene.GetRootGameObjects(rootGameObjects);
		}
		// 递归查找可以合并的mesh
		Dictionary<Material,CombineInstance[]> combineInstanceses = new Dictionary<Material, CombineInstance[]>();
		Recurrence(rootGameObjects, combineInstanceses);
		foreach (var combineInstances in combineInstanceses)
		{
			Mesh instance = new Mesh();
			instance.CombineMeshes(combineInstances.Value);
			// 如果是直接使用
			var testObj = new GameObject();
			var meshFilter = testObj.AddComponent<MeshFilter>();
			var meshRender = testObj.AddComponent<MeshRenderer>();
			meshFilter.mesh = instance;
			meshRender.material = combineInstances.Key;
			// 如果是需要保存下来作为运行时使用！
			// AssetDatabase.CreateAsset(instance, "path/name.assets");
		}
	}

	private static void Recurrence(List<GameObject> objs, Dictionary<Material,CombineInstance[]> list)
	{
		Dictionary<Material, List<MeshFilter>> dictionary = new Dictionary<Material, List<MeshFilter>>();
		foreach (var o in objs)
		{
			ResearchGameObject(o, dictionary);
		}
		foreach (var staticObjs in dictionary)
		{
			CombineInstance[] combineInstances = new CombineInstance[staticObjs.Value.Count];
			for (int i = 0; i < staticObjs.Value.Count; i++)
			{
				combineInstances[i] = new CombineInstance();
				combineInstances[i].mesh = staticObjs.Value[i].sharedMesh;
				combineInstances[i].transform = staticObjs.Value[i].transform.localToWorldMatrix;
				// 有需要的可以看着官方文档去添加一些属性的记录
				// combineInstances[i].realtimeLightmapScaleOffset
			}
			list.Add(staticObjs.Key, combineInstances);
		}
	}

	private static void ResearchGameObject(GameObject gameObject, Dictionary<Material,List<MeshFilter>> dictionary)
	{
		var flag = GameObjectUtility.GetStaticEditorFlags(gameObject);
		if (flag == StaticEditorFlags.BatchingStatic)
		{
			var meshFilter = gameObject.GetComponent<MeshFilter>();
			var meshRenderer = gameObject.GetComponent<MeshRenderer>();
			List<MeshFilter> meshFilters;
			if (!dictionary.TryGetValue(meshRenderer.sharedMaterial, out meshFilters))
			{
				meshFilters = new List<MeshFilter>();
				dictionary.Add(meshRenderer.sharedMaterial, meshFilters);
			}
			meshFilters.Add(meshFilter);
		}

		int childCount = gameObject.transform.childCount;
		for (int i = 0; i < childCount; i++)
		{
			ResearchGameObject(gameObject.transform.GetChild(i).gameObject, dictionary);
		}
	}
}
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