Unity5.x场景优化之动态设置光照贴图lightmap

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：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

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：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

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：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76

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 ( ) ;      } }

没截图从觉得少点什么，来，上图，先打开一个被烘培过的场景，场景根节点为scene_root，被烘培的gameobjet是地板、一颗小草、带logo的立方体：

然后使用工具给场景里面的相关节点挂脚本存数据：

把场景根节点scene_root拖出来做成prefab，然后删掉场景里面的scene_root，再把scene_root.prefab拖进场景里面：

此时模型是丢失了光照数据的，原因截图已说明。接着运行场景：

模型的光照又回来啦，原因截图已说明。