Additive方式加载场景真机上存在的光照贴图问题
在场景光照贴图这块，最近遇到了一个场景莫名变暗的问题。记录如下
- 在AB模式下，使用Additive方式加载场景（3D物件场景，有进行烘焙）
- 加载3个场景a,b,c
- 卸载掉一个场景a
- 然后执行AB卸载（true方式卸载），会发现剩下两个的场景b，c的光照贴图变暗了
（场景光照贴图卸载ab后与卸载ab前对比）
- 再加载回场景a，发现变暗的光照贴图恢复了，但是场景b，c的光照贴图UV错乱了。场景a的光照贴图正常
分析
在mac用ab模式执行了测试后，采集了在上述几个步骤中，光照贴图数组（LightmapSettings.lightmaps）的数据变化。（标橙色的是场景a所用的光照贴图）
| 操作 | 加载a,b,c | 卸载a | AB卸载 | 加载1 |
| 表现结果 | 光照正常 | 光照正常 | 光照异常：光照贴图变黑 | 光照异常：光照贴图UV错误；新场景光照正常 变暗的光照贴图恢复了 |
| 分析 | 有重复光照贴图? 非Additive模式？：不会有重复。场景切换会数组会重置干净 |
并没有全部卸载掉1所用的光照贴图 | 场景1所用的全部被清理掉了 | 物件Render的LMIndex不变，但是数组里面对应Index的贴图已改变 |
| Index0,grassland01_LMA5_final | Index0,grassland01_LMA5_final | Index0, | Index0,grassland01_LMA5_final | |
| Index1,grassland01_LMA4_final | Index1, | Index1, | Index1,grassland01_LMA4_final | |
| Index2,grassland01_LMA7_final | Index2, | Index2, | Index2,grassland01_LMA7_final | |
| Index3,grassland01_LMA6_final | Index3, | Index3, | Index3,grassland01_LMA6_final | |
| Index4,grassland01_LMA3_final | Index4, | Index4, | Index4,grassland01_LMA3_final | |
| Index5,grassland01_LM31_final | Index5, | Index5, | Index5,grassland01_LM31_final | |
| Index6,grassland01_LMA1_final | Index6, | Index6, | Index6,grassland01_LMA1_final | |
| Index7,grassland01_LMA2_final | Index7, | Index7, | Index7,grassland01_LMA2_final | |
| Index8,grassland01_LMA5_final | Index8,grassland01_LMA5_final | Index8, | Index8, | |
| Index9,grassland01_LMA4_final | Index9,grassland01_LMA4_final | Index9, | Index9, | |
| Index10,grassland01_LMA7_final | Index10,grassland01_LMA7_final | Index10, | Index10, | |
| Index11,grassland01_LMA6_final | Index11,grassland01_LMA6_final | Index11, | Index11, | |
| Index12,grassland01_LMA3_final | Index12,grassland01_LMA3_final | Index12, | Index12, | |
| Index13,grassland01_LM31_final | Index13,grassland01_LM31_final | Index13, | Index13, | |
| Index14,grassland01_LMA1_final | Index14,grassland01_LMA1_final | Index14, | Index14, | |
| Index15,grassland01_LMA2_final | Index15,grassland01_LMA2_final | Index15, | Index15,grassland02_LMA2_final | |
| Index16,grassland02_LMA2_final | Index16,grassland02_LMA2_final | Index16,grassland02_LMA2_final | Index16,grassland02_LMA3_final | |
| Index17,grassland02_LMA3_final | Index17,grassland02_LMA3_final | Index17,grassland02_LMA3_final | Index17,grassland02_LMA4_final | |
| Index18,grassland02_LMA4_final | Index18,grassland02_LMA4_final | Index18,grassland02_LMA4_final | Index18,grassland02_LM34_final | |
| Index19,grassland02_LM34_final | Index19,grassland02_LM34_final | Index19,grassland02_LM34_final | Index19,grassland02_LMA1_final | |
| Index20,grassland02_LMA1_final | Index20,grassland02_LMA1_final | Index20,grassland02_LMA1_final | Index20,grassland02_LMA2_final | |
| Index21,grassland02_LMA2_final | Index21,grassland02_LMA2_final | Index21,grassland02_LMA2_final | Index21,grassland02_LMA3_final | |
| Index22,grassland02_LMA3_final | Index22,grassland02_LMA3_final | Index22,grassland02_LMA3_final | Index22,grassland02_LMA4_final | |
| Index23,grassland02_LMA4_final | Index23,grassland02_LMA4_final | Index23,grassland02_LMA4_final | Index23,grassland02_LM34_final | |
| Index24,grassland02_LM34_final | Index24,grassland02_LM34_final | Index24,grassland02_LM34_final | Index24,grassland02_LMA1_final | |
| Index25,grassland02_LMA1_final | Index25,grassland02_LMA1_final | Index25,grassland02_LMA1_final | Index25,grassland03_LMA6_final | |
| Index26,grassland03_LMA6_final | Index26,grassland03_LMA6_final | Index26,grassland03_LMA6_final | Index26,grassland03_LMA5_final | |
| Index27,grassland03_LMA5_final | Index27,grassland03_LMA5_final | Index27,grassland03_LMA5_final | Index27,grassland03_LMA7_final | |
| Index28,grassland03_LMA7_final | Index28,grassland03_LMA7_final | Index28,grassland03_LMA7_final | Index28,grassland03_LMA9_final | |
| Index29,grassland03_LMA9_final | Index29,grassland03_LMA9_final | Index29,grassland03_LMA9_final | Index29,grassland03_LMA4_final | |
| Index30,grassland03_LMA4_final | Index30,grassland03_LMA4_final | Index30,grassland03_LMA4_final | Index30,grassland03_LMA1_final | |
| Index31,grassland03_LMA1_final | Index31,grassland03_LMA1_final | Index31,grassland03_LMA1_final | Index31,grassland03_LM57_final | |
| Index32,grassland03_LM57_final | Index32,grassland03_LM57_final | Index32,grassland03_LM57_final | Index32,grassland03_LMA3_final | |
| Index33,grassland03_LMA3_final | Index33,grassland03_LMA3_final | Index33,grassland03_LMA3_final | Index33,grassland03_LMA2_final | |
| Index34,grassland03_LMA2_final | Index34,grassland03_LMA2_final | Index34,grassland03_LMA2_final | Index34,grassland03_LMA6_final | |
| Index35,grassland03_LMA6_final | Index35,grassland03_LMA6_final | Index35,grassland03_LMA6_final | Index35,grassland03_LMA5_final | |
| Index36,grassland03_LMA5_final | Index36,grassland03_LMA5_final | Index36,grassland03_LMA5_final | Index36,grassland03_LMA7_final | |
| Index37,grassland03_LMA7_final | Index37,grassland03_LMA7_final | Index37,grassland03_LMA7_final | Index37,grassland03_LMA9_final | |
| Index38,grassland03_LMA9_final | Index38,grassland03_LMA9_final | Index38,grassland03_LMA9_final | Index38,grassland03_LMA4_final | |
| Index39,grassland03_LMA4_final | Index39,grassland03_LMA4_final | Index39,grassland03_LMA4_final | Index39,grassland03_LMA1_final | |
| Index40,grassland03_LMA1_final | Index40,grassland03_LMA1_final | Index40,grassland03_LMA1_final | Index40,grassland03_LM57_final | |
| Index41,grassland03_LM57_final | Index41,grassland03_LM57_final | Index41,grassland03_LM57_final | Index41,grassland03_LMA3_final | |
| Index42,grassland03_LMA3_final | Index42,grassland03_LMA3_final | Index42,grassland03_LMA3_final | Index42,grassland03_LMA2_final | |
| Index43,grassland03_LMA2_final | Index43,grassland03_LMA2_final | Index43,grassland03_LMA2_final | Index43,grassland01_LMA5_final | |
| Index44,grassland01_LMA4_final | ||||
| Index45,grassland01_LMA7_final | ||||
| Index46,grassland01_LMA6_final | ||||
| Index47,grassland01_LMA3_final | ||||
| Index48,grassland01_LM31_final | ||||
| Index49,grassland01_LMA1_final | ||||
| Index50,grassland01_LMA2_final |
发现了几个要点：
- 在数组中有两份重复的光照贴图数据
- 卸载a后，并没有卸载掉a所有的光照贴图，有残留了一份在数组里，而且index为0的数据始终不会被清除
- 执行卸载ab强制卸载资源后，所有a所用的光照贴图被清除了。这时其他场景的光照贴图变暗了。经谷歌原因是index为0的数据被清除后，就会导致变暗（具体原因不清楚，可能是Unity的bug）
- index为0的数据被清除后，如果后续加载了新的光照贴图，会导致数据错乱
尝试主场景烘焙一张比较小的光照贴图，以保证光照贴图数组中index为0一直有数据，不会被清空。重新测试后，解决了变暗的问题。
重新采集了光照贴图数组数据：（标橙色的还是场景a所用的光照贴图，绿色的是主场景所用光照贴图）
| 操作 | 加载1,2，3 | 卸载1 | AB卸载 | 加载1 |
| 正常 | 正常 | 正常 | 正常 | |
| Index0,Lightmap-0_comp_light | Index0,Lightmap-0_comp_light | Index0,Lightmap-0_comp_light | Index0,Lightmap-0_comp_light | |
| Index1,grassland01_LMA5_final | Index1, | Index1, | Index1,grassland01_LMA5_final | |
| Index2,grassland01_LMA4_final | Index2, | Index2, | Index2,grassland01_LMA4_final | |
| Index3,grassland01_LMA7_final | Index3, | Index3, | Index3,grassland01_LMA7_final | |
| Index4,grassland01_LMA6_final | Index4, | Index4, | Index4,grassland01_LMA6_final | |
| Index5,grassland01_LMA3_final | Index5, | Index5, | Index5,grassland01_LMA3_final | |
| Index6,grassland01_LM31_final | Index6, | Index6, | Index6,grassland01_LM31_final | |
| Index7,grassland01_LMA1_final | Index7, | Index7, | Index7,grassland01_LMA1_final | |
| Index8,grassland01_LMA2_final | Index8, | Index8, | Index8,grassland01_LMA2_final | |
| Index9,grassland01_LMA5_final | Index9,grassland01_LMA5_final | Index9, | Index9, | |
| Index10,grassland01_LMA4_final | Index10,grassland01_LMA4_final | Index10, | Index10, | |
| Index11,grassland01_LMA7_final | Index11,grassland01_LMA7_final | Index11, | Index11, | |
| Index12,grassland01_LMA6_final | Index12,grassland01_LMA6_final | Index12, | Index12, | |
| Index13,grassland01_LMA3_final | Index13,grassland01_LMA3_final | Index13, | Index13, | |
| Index14,grassland01_LM31_final | Index14,grassland01_LM31_final | Index14, | Index14, | |
| Index15,grassland01_LMA1_final | Index15,grassland01_LMA1_final | Index15, | Index15, | |
| Index16,grassland01_LMA2_final | Index16,grassland01_LMA2_final | Index16, | Index16, | |
| Index17,grassland02_LMA2_final | Index17,grassland02_LMA2_final | Index17,grassland02_LMA2_final | Index17,grassland02_LMA2_final | |
| Index18,grassland02_LMA3_final | Index18,grassland02_LMA3_final | Index18,grassland02_LMA3_final | Index18,grassland02_LMA3_final | |
| Index19,grassland02_LMA4_final | Index19,grassland02_LMA4_final | Index19,grassland02_LMA4_final | Index19,grassland02_LMA4_final | |
| Index20,grassland02_LM34_final | Index20,grassland02_LM34_final | Index20,grassland02_LM34_final | Index20,grassland02_LM34_final | |
| Index21,grassland02_LMA1_final | Index21,grassland02_LMA1_final | Index21,grassland02_LMA1_final | Index21,grassland02_LMA1_final | |
| Index22,grassland02_LMA2_final | Index22,grassland02_LMA2_final | Index22,grassland02_LMA2_final | Index22,grassland02_LMA2_final | |
| Index23,grassland02_LMA3_final | Index23,grassland02_LMA3_final | Index23,grassland02_LMA3_final | Index23,grassland02_LMA3_final | |
| Index24,grassland02_LMA4_final | Index24,grassland02_LMA4_final | Index24,grassland02_LMA4_final | Index24,grassland02_LMA4_final | |
| Index25,grassland02_LM34_final | Index25,grassland02_LM34_final | Index25,grassland02_LM34_final | Index25,grassland02_LM34_final | |
| Index26,grassland02_LMA1_final | Index26,grassland02_LMA1_final | Index26,grassland02_LMA1_final | Index26,grassland02_LMA1_final | |
| Index27,grassland03_LMA6_final | Index27,grassland03_LMA6_final | Index27,grassland03_LMA6_final | Index27,grassland03_LMA6_final | |
| Index28,grassland03_LMA5_final | Index28,grassland03_LMA5_final | Index28,grassland03_LMA5_final | Index28,grassland03_LMA5_final | |
| Index29,grassland03_LMA7_final | Index29,grassland03_LMA7_final | Index29,grassland03_LMA7_final | Index29,grassland03_LMA7_final | |
| Index30,grassland03_LMA9_final | Index30,grassland03_LMA9_final | Index30,grassland03_LMA9_final | Index30,grassland03_LMA9_final | |
| Index31,grassland03_LMA4_final | Index31,grassland03_LMA4_final | Index31,grassland03_LMA4_final | Index31,grassland03_LMA4_final | |
| Index32,grassland03_LMA1_final | Index32,grassland03_LMA1_final | Index32,grassland03_LMA1_final | Index32,grassland03_LMA1_final | |
| Index33,grassland03_LM57_final | Index33,grassland03_LM57_final | Index33,grassland03_LM57_final | Index33,grassland03_LM57_final | |
| Index34,grassland03_LMA3_final | Index34,grassland03_LMA3_final | Index34,grassland03_LMA3_final | Index34,grassland03_LMA3_final | |
| Index35,grassland03_LMA2_final | Index35,grassland03_LMA2_final | Index35,grassland03_LMA2_final | Index35,grassland03_LMA2_final | |
| Index36,grassland03_LMA6_final | Index36,grassland03_LMA6_final | Index36,grassland03_LMA6_final | Index36,grassland03_LMA6_final | |
| Index37,grassland03_LMA5_final | Index37,grassland03_LMA5_final | Index37,grassland03_LMA5_final | Index37,grassland03_LMA5_final | |
| Index38,grassland03_LMA7_final | Index38,grassland03_LMA7_final | Index38,grassland03_LMA7_final | Index38,grassland03_LMA7_final | |
| Index39,grassland03_LMA9_final | Index39,grassland03_LMA9_final | Index39,grassland03_LMA9_final | Index39,grassland03_LMA9_final | |
| Index40,grassland03_LMA4_final | Index40,grassland03_LMA4_final | Index40,grassland03_LMA4_final | Index40,grassland03_LMA4_final | |
| Index41,grassland03_LMA1_final | Index41,grassland03_LMA1_final | Index41,grassland03_LMA1_final | Index41,grassland03_LMA1_final | |
| Index42,grassland03_LM57_final | Index42,grassland03_LM57_final | Index42,grassland03_LM57_final | Index42,grassland03_LM57_final | |
| Index43,grassland03_LMA3_final | Index43,grassland03_LMA3_final | Index43,grassland03_LMA3_final | Index43,grassland03_LMA3_final | |
| Index44,grassland03_LMA2_final | Index44,grassland03_LMA2_final | Index44,grassland03_LMA2_final | Index44,grassland03_LMA2_final | |
| Index45,grassland01_LMA5_final | ||||
| Index46,grassland01_LMA4_final | ||||
| Index47,grassland01_LMA7_final | ||||
| Index48,grassland01_LMA6_final | ||||
| Index49,grassland01_LMA3_final | ||||
| Index50,grassland01_LM31_final | ||||
| Index51,grassland01_LMA1_final | ||||
| Index52,grassland01_LMA2_final |
仍然存在的问题是光照贴图数组长度会增加，待后续解决