prefab内容分析
本文转自：https://www.cnblogs.com/blueberryzzz/p/9097391.html，请点击链接查看原文，尊重楼主版权。(有个人轻微修改)
前言：
如果打开prefab文件是乱码，则Unity中点击Edit-Project Setting-Editor,然后在Inspector面板中AssetSerialization里选择ForceText。(本文Unity版本为2017.4.12，与5.x版本有些不同)
一、什么是Prefab
Prefab是unity3d中的一种资源类型，用于存储可重复使用的游戏对象，来方便快捷的创建实例。
通过prefab在场景中创建的所有实例，都会链接到原始的prefab，所以当修改原始的prefab时，所有场景中的所有prefab实例都会被修改。
二、Prefab文件的内容
Prefab文件的内容是通过YAML语言序列化的一个GameObject的对象，包含了这个GameObject的所有描述信息（GameObject信息、Compent实例和属性等）。
三、从一个UI的Prefab说起
prefab文件的内容
一个MainUI空物体下有：一个Image组件使用了RectTransform-CanvasRenderer-Image组件，一个Text使用了RectTransform-CanvasRenderer-NewTempText组件，NewTempText继承自UGUI的Text。
%YAML 1.1
%TAG !u! tag:unity3d.com,2011:
--- !u!1001 &100100000
Prefab:
m_ObjectHideFlags: 1
serializedVersion: 2
m_Modification:
m_TransformParent: {fileID: 0}
m_Modifications: []
m_RemovedComponents: []
m_ParentPrefab: {fileID: 0}
m_RootGameObject: {fileID: 1584932412801430}
m_IsPrefabParent: 1
--- !u!1 &1371898556151132
GameObject:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
serializedVersion: 5
m_Component:
- component: {fileID: 224403532645876076}
- component: {fileID: 222392532102221554}
- component: {fileID: 114249348854969090}
m_Layer: 0
m_Name: Image
m_TagString: Untagged
m_Icon: {fileID: 0}
m_NavMeshLayer: 0
m_StaticEditorFlags: 0
m_IsActive: 1
--- !u!1 &1477442230281094
GameObject:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
serializedVersion: 5
m_Component:
- component: {fileID: 224125095733739228}
- component: {fileID: 222881951360802480}
- component: {fileID: 114755593969431376}
m_Layer: 0
m_Name: Text
m_TagString: Untagged
m_Icon: {fileID: 0}
m_NavMeshLayer: 0
m_StaticEditorFlags: 0
m_IsActive: 1
--- !u!1 &1584932412801430
GameObject:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
serializedVersion: 5
m_Component:
- component: {fileID: 224345533291003680}
m_Layer: 0
m_Name: MainUI
m_TagString: Untagged
m_Icon: {fileID: 0}
m_NavMeshLayer: 0
m_StaticEditorFlags: 0
m_IsActive: 1
--- !u!114 &114249348854969090
MonoBehaviour:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1371898556151132}
m_Enabled: 1
m_EditorHideFlags: 0
m_Script: {fileID: -765806418, guid: f70555f144d8491a825f0804e09c671c, type: 3}
m_Name:
m_EditorClassIdentifier:
m_Material: {fileID: 0}
m_Color: {r: 1, g: 1, b: 1, a: 1}
m_RaycastTarget: 1
m_OnCullStateChanged:
m_PersistentCalls:
m_Calls: []
m_TypeName: UnityEngine.UI.MaskableGraphic+CullStateChangedEvent, UnityEngine.UI,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
m_Sprite: {fileID: 0}
m_Type: 0
m_PreserveAspect: 0
m_FillCenter: 1
m_FillMethod: 4
m_FillAmount: 1
m_FillClockwise: 1
m_FillOrigin: 0
--- !u!114 &114755593969431376
MonoBehaviour:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1477442230281094}
m_Enabled: 1
m_EditorHideFlags: 0
m_Script: {fileID: 11500000, guid: a9148530f8f3cbf4daf4b87f1ac10dde, type: 3}
m_Name:
m_EditorClassIdentifier:
m_Material: {fileID: 0}
m_Color: {r: 1, g: 1, b: 1, a: 1}
m_RaycastTarget: 1
m_OnCullStateChanged:
m_PersistentCalls:
m_Calls: []
m_TypeName: UnityEngine.UI.MaskableGraphic+CullStateChangedEvent, UnityEngine.UI,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
m_FontData:
m_Font: {fileID: 10102, guid: 0000000000000000e000000000000000, type: 0}
m_FontSize: 14
m_FontStyle: 0
m_BestFit: 0
m_MinSize: 10
m_MaxSize: 40
m_Alignment: 0
m_AlignByGeometry: 0
m_RichText: 1
m_HorizontalOverflow: 0
m_VerticalOverflow: 0
m_LineSpacing: 1
m_Text: AA
isNew: 1
--- !u!222 &222392532102221554
CanvasRenderer:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1371898556151132}
--- !u!222 &222881951360802480
CanvasRenderer:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1477442230281094}
--- !u!224 &224125095733739228
RectTransform:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1477442230281094}
m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 0, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}
m_Children: []
m_Father: {fileID: 224345533291003680}
m_RootOrder: 1
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_AnchorMin: {x: 0.5, y: 0.5}
m_AnchorMax: {x: 0.5, y: 0.5}
m_AnchoredPosition: {x: 0, y: 0}
m_SizeDelta: {x: 160, y: 30}
m_Pivot: {x: 0.5, y: 0.5}
--- !u!224 &224345533291003680
RectTransform:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1584932412801430}
m_LocalRotation: {x: -0, y: -0, z: -0, w: 1}
m_LocalPosition: {x: 0, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}
m_Children:
- {fileID: 224403532645876076}
- {fileID: 224125095733739228}
m_Father: {fileID: 0}
m_RootOrder: 0
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_AnchorMin: {x: 0, y: 0}
m_AnchorMax: {x: 1, y: 1}
m_AnchoredPosition: {x: 0, y: 0}
m_SizeDelta: {x: 0, y: 0}
m_Pivot: {x: 0.5, y: 0.5}
--- !u!224 &224403532645876076
RectTransform:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1371898556151132}
m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 0, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}
m_Children: []
m_Father: {fileID: 224345533291003680}
m_RootOrder: 0
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_AnchorMin: {x: 0.5, y: 0.5}
m_AnchorMax: {x: 0.5, y: 0.5}
m_AnchoredPosition: {x: 0, y: 0}
m_SizeDelta: {x: 100, y: 100}
m_Pivot: {x: 0.5, y: 0.5}
分析其中内容
1.前两行内容是yaml语言的注释
2.接下来是prefab中所有对象的描述信息
每个元素的描述内容以--- !u!n1 & n2开头，其中n1代表元素的类型ID（每个ID的具体含义参考YAML Class ID Reference），n2代表这个元素的本地ID（fileID，在prefab文件中唯一）。
可以看到这个prefab中有Prefab，GameObject，MonoBehaviour，CanvasRenderer，RectTransform 几种类型。
除了Prefab对象代表prefab本身的信息，其他几个对象正是物体和组件的信息。
3.Prefab的详细说明
— !u!1001 &100100000
1001 代表这是一个Prefab,prefab的本地Id一般都是100100000。
m_RootGameObject交代了prefab根节点物体的本地ID。
<1>前两个下面再说
<2>m_Modification:
当一个prefab实例化到场景中的时候，代表场景prefab实例被修改的值，这些值不随原始prefab资源的修改而修改。
在原始prefab资源中是空的。
<3>m_ParentPrefab: {fileID: 0}
在场景中的一个prefab实例中代表这个prefab对应的原始perfab资源中的prefab对象。
在prefab实例中是0。
<4>m_RootGameObject: {fileID: 1584932412801430}
交代了prefab根节点物体的本地ID。
<5>m_IsPrefabParent: 1
可能是Prefab是资源还是实例的标记，不太确定。
4.第一个GameObject对象的详细说明(第一个GameObject不一定是根节点物体，例如这里第一个GameObject是子物体Image物体)
<1>— !u!1 &1371898556151132
1代表这是一个GameObject类型的对象，1371898556151132是这个GameObject对象在Prefab资源中的fileID(本地ID)。
<2>m_ObjectHideFlags：0
这个元素在Project视图中是否被隐藏，没被隐藏，值为0。(Project下Prefab一般只显示根节点和1级子节点，更深层次的被隐藏)
<3>m_PrefabParentObject: {fileID: 0}
代表场景中的prefab实例与原始prefab资源的链接，当一个prefab实例链接被破坏（删除prefab实例的一个子节点，或修改一个子节点父子关系），或其中的compent被剥离到场景文件中（stripped，比如prefab实例在场景中不是根节点，而是一个GameObject的子节点，那么prefab实例的transtrom就会被剥离到场景文件中，赋予一个fileID，用来描述prefab实例的父子关系）时，生成的对象的m_PrefabParentObject会对应到原始prefab资源中的对象。
在原始prefab资源中，所有对象的m_PrefabParentObject都是0，代表空。
<4>m_PrefabInternal: {fileID: 100100000}
该属性表示这个对象属于哪个prefab对象。
在场景中当一个compent被剥离时，会指向场景中的prefab实例。
在原始prefab资源中，因为prefab中只有一个prefab对象，fileID就是1000100000。
所以在原始prefab资源中，所有对象的m_PrefabInternal值都是{fileID: 100100000}。
Stripped举例：
新建一个叫testStripped的prefab，用一个空的GameObject给它赋值，然后将这个prefab拖到Main Camera下，保存场景文件后查看场景文件内容。
Transform:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 0}
m_GameObject: {fileID: 280358070}
m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 0, y: 1, z: -10}
m_LocalScale: {x: 1, y: 1, z: 1}
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_Children:
- {fileID: 619871928}
m_Father: {fileID: 0}
m_RootOrder: 0
--- !u!1001 &619871927
Prefab:
m_ObjectHideFlags: 0
serializedVersion: 2
m_Modification:
m_TransformParent: {fileID: 280358075}
m_Modifications:
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalPosition.x
value: 384.3385
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalPosition.y
value: 223.03131
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalPosition.z
value: 126.32626
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalRotation.x
value: 0
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalRotation.y
value: 0
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalRotation.z
value: 0
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_LocalRotation.w
value: 1
objectReference: {fileID: 0}
- target: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
propertyPath: m_RootOrder
value: 0
objectReference: {fileID: 0}
m_RemovedComponents: []
m_ParentPrefab: {fileID: 100100000, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
m_IsPrefabParent: 0
--- !u!4 &619871928 stripped
Transform:
m_PrefabParentObject: {fileID: 488654, guid: 617cd7fcc638efd44b4beab357086bc0, type: 2}
m_PrefabInternal: {fileID: 619871927}
<5>serializedVersion: 5
序列化的版本，跟unity版本有关，不太确定。
<6>m_Component:
该GameObject包含哪些component，包含的对象用fileID表示。这个GameObject包含了3个Component，分别是RectTransform，CanvasRenderer，Image。可在prefab内容的下方看到这些组件的详细信息。
<7>m_Layer: 0
GameObject所在的层级。
<8>m_Name: Image
GameObject的名称。
<9>m_TagString: Untagged
Tag。
<10>m_Icon: {fileID: 0}
图标，fileID为0代表没有图标。
图标会显示在场景中，比如选择这个红色的icon，在场景中就可以看到prefab上出现了一个红色的标签。0代表没有标签。
<11>m_NavMeshLayer: 0
GameObject的NavigationArea属性，与自动寻路有关。
<12>m_StaticEditorFlags: 0
GameObject的Static属性。
<13>m_IsActive: 1
GameObject是否是active状态。
4.接下来看下组件的信息
--- !u!224 &224403532645876076
RectTransform:
m_ObjectHideFlags: 1
m_PrefabParentObject: {fileID: 0}
m_PrefabInternal: {fileID: 100100000}
m_GameObject: {fileID: 1371898556151132}
m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 0, y: 0, z: 0}
m_LocalScale: {x: 1, y: 1, z: 1}
m_Children: []
m_Father: {fileID: 224345533291003680}
m_RootOrder: 0
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_AnchorMin: {x: 0.5, y: 0.5}
m_AnchorMax: {x: 0.5, y: 0.5}
m_AnchoredPosition: {x: 0, y: 0}
m_SizeDelta: {x: 100, y: 100}
m_Pivot: {x: 0.5, y: 0.5}
— !u!224 &224403532645876076
224表示RectTransform
然后下面列出了组件的一些数据信息
同样222表示CanvasRenderer，和这个类似。
然后看下Image组件：
— !u!114 &114249348854969090
114表示MonoBehaviour，代表脚本组件，不同于其他基本组件。
里面也列出了一些数据信息，注意比上面两个组件多了一个m_Script：
m_Script: {fileID: -765806418, guid: f70555f144d8491a825f0804e09c671c, type: 3}
这里的fileID是整这个组件引用的脚本文件的FileID，guid是这个脚本文件的GUID(全局唯一,记录在文件对应的的meta文件中)。
补充知识点：GUID与fileID(本地ID)
Unity会为每个导入到Assets目录中的资源创建一个meta文件，文件中记录了GUID，GUID用来记录资源之间的引用关系。还有fileID（本地ID），用于标识资源内部的资源。资源间的依赖关系通过GUID来确定；资源内部的依赖关系使用fileID来确定。
简单总结一下一个prefab的内容
prefab文件并不存储具体资源，而是使用了yaml语言描述了一个被序列化的GameObject对象中包含的所有GameObject，Component的信息。包括相互之间的关系、存储的数据和引用信息。
四、prefab在场景中的使用
1.简单介绍场景文件的内容
一个场景文件也是通过yaml语言序列化的场景内容，一个场景文件不仅包含显示在hierarchy中的GameObject、prefab信息，还包含了场景的设置信息。比prefab稍微复杂一些。
2.prefab文件在场景中的内容
新建一个test场景，将test拖入场景中，然后保存，查看场景中的Prefab实例信息。
--- !u!1001 &131130024
Prefab:
m_ObjectHideFlags: 0
serializedVersion: 2
m_Modification:
m_TransformParent: {fileID: 0}
m_Modifications:
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalPosition.x
value: 384.3385
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalPosition.y
value: 224.03131
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalPosition.z
value: 116.32626
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalRotation.x
value: 0
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalRotation.y
value: 0
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalRotation.z
value: 0
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_LocalRotation.w
value: 1
objectReference: {fileID: 0}
- target: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
propertyPath: m_RootOrder
value: 2
objectReference: {fileID: 0}
m_RemovedComponents: []
m_ParentPrefab: {fileID: 100100000, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
m_IsPrefabParent: 0
可以看到一个prefab被实例化到场景中时，没有将prefab资源中内容直接复制到场景中，而是生成了一个prefab对象。
m_ParentPrefab代表这个prefab对应的prefab资源。
m_Modification代表这个prefab实例中属性的修改信息，场景在读取一个prefab实例时，会查看prefab资源中的属性是否在m_Modification中存在，如果存在，则使用m_Modification中保存的值。这样就保证了修改了场景中的prefab实例的属性，不会被prefab资源的修改而覆盖。
正是这两个属性让prefab实例具有了与prefab资源同步修改，但会保存自己特性的功能。
3.Break Prefab Instance
如果我们希望一个prefab实例完全不随prefab的修改而修改，那么我们可以通过Break Prefab Instance选项实现。
将一个prefab实例Break之后，这个prefab就会像一个普通的GameObject存在场景中
--- !u!1 &765230757
GameObject:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 101978, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
m_PrefabInternal: {fileID: 0}
serializedVersion: 4
m_Component:
- 4: {fileID: 765230761}
- 33: {fileID: 765230760}
- 65: {fileID: 765230759}
- 23: {fileID: 765230758}
m_Layer: 0
m_Name: aCube
m_TagString: Untagged
m_Icon: {fileID: 0}
m_NavMeshLayer: 0
m_StaticEditorFlags: 0
m_IsActive: 1
--- !u!23 &765230758
MeshRenderer:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 2346436, guid: fda6bd048b136f44286b537a5526a83c,
type: 2}
m_PrefabInternal: {fileID: 0}
m_GameObject: {fileID: 765230757}
m_Enabled: 1
m_CastShadows: 1
m_ReceiveShadows: 1
m_Materials:
- {fileID: 10303, guid: 0000000000000000f000000000000000, type: 0}
m_SubsetIndices:
m_StaticBatchRoot: {fileID: 0}
m_UseLightProbes: 1
m_ReflectionProbeUsage: 1
m_ProbeAnchor: {fileID: 0}
m_ScaleInLightmap: 1
m_PreserveUVs: 1
m_IgnoreNormalsForChartDetection: 0
m_ImportantGI: 0
m_MinimumChartSize: 4
m_AutoUVMaxDistance: 0.5
m_AutoUVMaxAngle: 89
m_LightmapParameters: {fileID: 0}
m_SortingLayerID: 0
m_SortingOrder: 0
--- !u!65 &765230759
BoxCollider:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 6596578, guid: fda6bd048b136f44286b537a5526a83c,
type: 2}
m_PrefabInternal: {fileID: 0}
m_GameObject: {fileID: 765230757}
m_Material: {fileID: 0}
m_IsTrigger: 0
m_Enabled: 1
serializedVersion: 2
m_Size: {x: 1, y: 1, z: 1}
m_Center: {x: 0, y: 0, z: 0}
--- !u!33 &765230760
MeshFilter:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 3343092, guid: fda6bd048b136f44286b537a5526a83c,
type: 2}
m_PrefabInternal: {fileID: 0}
m_GameObject: {fileID: 765230757}
m_Mesh: {fileID: 10202, guid: 0000000000000000e000000000000000, type: 0}
--- !u!4 &765230761
Transform:
m_ObjectHideFlags: 0
m_PrefabParentObject: {fileID: 481870, guid: fda6bd048b136f44286b537a5526a83c, type: 2}
m_PrefabInternal: {fileID: 0}
m_GameObject: {fileID: 765230757}
m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
m_LocalPosition: {x: 384.3385, y: 224.03131, z: 116.32626}
m_LocalScale: {x: 1, y: 1, z: 1}
m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
m_Children: []
m_Father: {fileID: 0}
m_RootOrder: 2
每个元素的m_PrefabParentObject都指向了原始prefab资源中对应的对象。
右边的prefab表示也会变为黄色，这代表这个prefab虽然被break了，但是还可以通过与原始prefab资源的链接去select，revert或apply，来变回或修改原来的prefab实例。
再次声明：
本文转自：https://www.cnblogs.com/blueberryzzz/p/9097391.html，请点击链接查看原文，尊重楼主版权。