Unity5.x场景优化之动态设置光照贴图lightmap

最新推荐文章于 2025-02-25 10:53:57 发布

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最新推荐文章于 2025-02-25 10:53:57 发布

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分类专栏：知识点文章标签： Unity3d LightingMap 场景烘焙

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本文介绍了一种在Unity中管理光照贴图的方法，通过自定义组件保存和加载光照贴图数据，实现动态调整光照效果，适用于游戏开发中不同时间和季节的光照氛围营造。

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在很多情况下，我们为了提高渲染效率，一般都会让美术同学在制作场景时，设置场景相关节点的lightmap static属性，提前给整个场景烘培出静态的光照贴图lightmap，烘培的数据保存在场景目录下的LightmapSnapshot文件中，主要包括的数据有：

lightmaps：烘培出的光照贴图数组；

gameobject uid：被烘培的gameobject的唯一标识；

renderer的lightmapIndex：被烘培的gameobject的renderer组件所指向的光照贴图数组的索引；

renderer的lightmapScaleOffset：被烘培的gameobject的renderer组件所指向的光照贴图用于采样的区域坐标和宽高；

这个文件目前没有相关api读写，如果你想烘培完场景之后，把场景里面的gameobjet抽出来做成prefab，等切换完场景之后再用于动态加载是不可行的，因为抽出来的prefab在Instantiate之后将会是一个新的gameobject，uid自然和LightmapSnapshot文件里面记录的不一样，导致找不到对应的光照数据而造成模型没光照变暗或渲染错乱。

还有一种比较常见的需求是，在游戏运行时，通过更换光照贴图数据，营造场景在不同时间或季节的光照氛围，例如白天和黑夜等。

so，就算场景烘培完之后，我们还是要“动”它。

做法大概是，既然LightmapSnapshot文件我们不能动，那就把上面提到的光照数据保存到我们可以控制的文件里面，例如prefab。

首先，给场景根节点挂一个自定义组件，用于保存烘培出的光照贴图数组和烘培模式：

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using UnityEngine;
using System.Collections;
 
[ExecuteInEditMode]
public class SceneLightMapSetting : MonoBehaviour {
    public Texture2D []lightmapFar, lightmapNear;
    public LightmapsMode mode;
 
    public void SaveSettings()
    {
        mode = LightmapSettings.lightmapsMode;
        lightmapFar = null;
        lightmapNear = null;
        if (LightmapSettings.lightmaps != null && LightmapSettings.lightmaps.Length > 0)
        {
            int l = LightmapSettings.lightmaps.Length;
            lightmapFar = new Texture2D[l];
            lightmapNear = new Texture2D[l];
            for (int i = 0; i < l; i++)
            {
                lightmapFar[i] = LightmapSettings.lightmaps[i].lightmapFar;
                lightmapNear[i] = LightmapSettings.lightmaps[i].lightmapNear;
            }
        }
        RendererLightMapSetting[] savers = Transform.FindObjectsOfType<RendererLightMapSetting>();
        foreach(RendererLightMapSetting s in savers)
        {
            s.SaveSettings();
        }
   }
 
    public void LoadSettings()
    {
        LightmapSettings.lightmapsMode = mode;
        int l1 = (lightmapFar == null) ? 0 : lightmapFar.Length;
        int l2 = (lightmapNear == null) ? 0 : lightmapNear.Length;
        int l = (l1 < l2) ? l2 : l1;
        LightmapData[] lightmaps = null;
        if (l > 0)
        {
            lightmaps = new LightmapData[l];
            for (int i = 0; i < l; i++)
            {
                lightmaps[i] = new LightmapData();
                if (i < l1)
                    lightmaps[i].lightmapFar = lightmapFar[i];
                if (i < l2)
                    lightmaps[i].lightmapNear = lightmapNear[i];
            }
 
            LightmapSettings.lightmaps = lightmaps;
        }
    }
 
    void OnEnable()
    {
#if UNITY_EDITOR
        UnityEditor.Lightmapping.completed += SaveSettings;
#endif
    }
    void OnDisable()
    {
#if UNITY_EDITOR
        UnityEditor.Lightmapping.completed -= SaveSettings;
#endif
    }
 
    void Awake () {
        if(Application.isPlaying){
            LoadSettings();
        }
    }
}

再给场景里面被烘培的gameobject挂一组件，用于保存光照贴图数组的索引和光照贴图的区域坐标和宽高数据：

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using UnityEngine;
using System.Collections;
 
[ExecuteInEditMode]
public class RendererLightMapSetting : MonoBehaviour {
    public int lightmapIndex;
    public Vector4 lightmapScaleOffset;
 
    public void SaveSettings()
    {
        if(!IsLightMapGo(gameObject)){
            return;
        }
        Renderer renderer = GetComponent<Renderer>();
        lightmapIndex = renderer.lightmapIndex;
        lightmapScaleOffset = renderer.lightmapScaleOffset;
    }
 
    public void LoadSettings()
    {
        if(!IsLightMapGo(gameObject)){
            return;
        }
 
        Renderer renderer = GetComponent<Renderer>();
        renderer.lightmapIndex = lightmapIndex;
        renderer.lightmapScaleOffset = lightmapScaleOffset;
    }
 
    public static bool IsLightMapGo(GameObject go){
        if(go == null){
            return false;
        }
        Renderer renderer = go.GetComponent<Renderer>();
        if(renderer == null){
            return false;
        }
        return true;
    }
 
    void Awake () {
        if (Application.isPlaying) {
            LoadSettings ();
        }
    }
}

如果手动挂上面两个脚本的话，繁琐且容易出错，so，写工具接口，用工具扫场景挂脚本：

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using UnityEngine;
using UnityEditor;
using System.IO;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System;
 
public class SceneTools
{
    static string[] _sNeedAssetType = new string[1]{
        ".unity",
    };
 
    [MenuItem("场景相关/1. 保存场景光照贴图信息", false, 111)]
    public static void SaveSceneMapLightSetting()
    {
        UnityEngine.Object[] selObjs = Selection.GetFiltered (typeof(UnityEngine.Object), SelectionMode.DeepAssets);
        if (selObjs == null || selObjs.Length == 0) {
            Debug.LogError ("请到\"Scenes\" 目录下选中需要保存场景光照贴图信息的场景!");
            return;
        }
 
        string assetPath;
        UnityEngine.Object assetObj = null;
        GameObject gameObj = null;
        SceneLightMapSetting slms = null;
        RendererLightMapSetting rlms = null;
        bool needSave = false;
        for (int i = 0; i < selObjs.Length; ++i) {
            needSave = false;
            assetPath = AssetDatabase.GetAssetPath (selObjs [i]);
            foreach (string extName in _sNeedAssetType) {
                if (assetPath.EndsWith (extName)) {
                    needSave = true;
                    break;
                }
            }
            if (!needSave)
                continue;
 
            assetObj = AssetDatabase.LoadAssetAtPath (assetPath, typeof(UnityEngine.Object)) as UnityEngine.Object;
            EditorApplication.OpenScene (assetPath);
 
            gameObj = GameObject.Find ("scene_root");
            if (gameObj == null) {
                Debug.LogError ("不合法的场景：场景没有scene_root根节点！！");
                continue;
            }
 
            slms = gameObj.GetComponent<SceneLightMapSetting>();
            if(slms == null){
                slms = gameObj.AddComponent<SceneLightMapSetting>();
            }
 
            Renderer[] savers = Transform.FindObjectsOfType<Renderer>();
            foreach(Renderer s in savers)
            {
                if(s.lightmapIndex != -1){
                    rlms = s.gameObject.GetComponent<RendererLightMapSetting>();
                    if(rlms == null){
                        rlms = s.gameObject.AddComponent<RendererLightMapSetting>();
                    }
                }
            }
 
            slms.SaveSettings();
 
            EditorApplication.SaveScene();
 
            Debug.Log(string.Format("场景{0}的光照贴图信息保存完成", assetObj.name));
        }
        EditorApplication.SaveAssets();
    }
}