GetChangeVersion
Gets the change version number assigned to the specified type of component in this chunk.
Read time 7 minutesLast updated a day ago
Definition
- Type: Method
- Namespace: Unity.Entities
- Assembly: UnityEngine.EntitiesModule
GetChangeVersion<T>(ComponentTypeHandle<T>)
Gets the change version number assigned to the specified type of component in this chunk.
public readonly uint GetChangeVersion<T>(ref ComponentTypeHandle<T> typeHandle) where T : IComponentData
Parameters
An object containing type and job safety information. To create this object, call ComponentSystemBase.GetComponentTypeHandle. Pass the object to a job using a public field you define as part of the job struct.
Returns
Type | Description |
|---|---|
| uint | The current version number of the specified component, which is the version set the last time a system accessed a component of that type in this chunk with write privileges. Returns 0 if the chunk does not contain a component of the specified type. |
Remarks
Every time a system accesses components in a chunk, the system updates the change version of any component types to which it has write access with the current ComponentSystemBase.GlobalSystemVersion. (A system updates the version whether or not you actually write any component data -- always specify read-only access when possible.)
You can use the change version to filter out entities that have not changed since the last time a system ran. Implement change filtering using one of the following:
-
Entities.ForEach.WithChangeFilter(ComponentType)
-
ArchetypeChunk.DidChange in an IJobChunk job.
Note that change versions are stored at the chunk level. Thus when you use change filtering, the query system excludes or includes whole chunks not individual entities.
GetChangeVersion(DynamicComponentTypeHandle)
Gets the change version number assigned to the specified type of component in this chunk.
public readonly uint GetChangeVersion(ref DynamicComponentTypeHandle typeHandle)
Parameters
An object containing type and job safety information. To create this object, call ComponentSystemBase.GetDynamicComponentTypeHandle. Pass the object to a job using a public field you define as part of the job struct.
Returns
Type | Description |
|---|---|
| uint | The current version number of the specified component, which is the version set the last time a system accessed a component of that type in this chunk with write privileges. Returns 0 if the chunk does not contain a component of the specified type. |
Remarks
Every time a system accesses components in a chunk, the system updates the change version of any component types to which it has write access with the current ComponentSystemBase.GlobalSystemVersion. (A system updates the version whether or not you actually write any component data -- always specify read-only access when possible.)
You can use the change version to filter out entities that have not changed since the last time a system ran. Implement change filtering using one of the following:
-
Entities.ForEach.WithChangeFilter(ComponentType)
-
ArchetypeChunk.DidChange in an IJobChunk job.
Note that change versions are stored at the chunk level. Thus when you use change filtering, the query system excludes or includes whole chunks not individual entities.
GetChangeVersion<T>(BufferTypeHandle<T>)
Gets the change version number assigned to the specified type of dynamic buffer component in this chunk.
public readonly uint GetChangeVersion<T>(ref BufferTypeHandle<T> bufferTypeHandle) where T : unmanaged, IBufferElementData
Parameters
An object containing type and job safety information. To create this object, call ComponentSystemBase.GetBufferTypeHandle. Pass the object to a job using a public field you define as part of the job struct.
Returns
Type | Description |
|---|---|
| uint | The current version number of the specified dynamic buffer type, which is the version set the last time a system accessed a buffer component of that type in this chunk with write privileges. Returns 0 if the chunk does not contain a buffer component of the specified type. |
Remarks
Every time a system accesses components in a chunk, the system updates the change version of any component types to which it has write access with the current ComponentSystemBase.GlobalSystemVersion. (A system updates the version whether or not you actually write any component data -- always specify read-only access when possible.)
You can use the change version to filter out entities that have not changed since the last time a system ran. Implement change filtering using one of the following:
-
Entities.ForEach.WithChangeFilter(ComponentType)
-
ArchetypeChunk.DidChange in an IJobChunk job.
Note that change versions are stored at the chunk level. Thus if you use change filtering, the query system excludes or includes whole chunks not individual entities.
GetChangeVersion(TransformTypeHandle)
Gets the change version number assigned to TransformRef in this chunk.
public readonly uint GetChangeVersion(ref TransformTypeHandle transformTypeHandle)
Parameters
An object containing type and job safety information. To create this object, call SystemState.GetTransformTypeHandle. Pass the object to a job using a public field you define as part of the job struct.
Returns
Type | Description |
|---|---|
| uint | The current version number of TransformRef, which is the version set the last time a system accessed a transform in this chunk with write privileges. Returns 0 if the chunk does not contain TransformRef. |
Remarks
Every time a system accesses transforms in a chunk, the system updates the change version of TransformRef if it has write access, with the current SystemState.GlobalSystemVersion. (A system updates the version whether or not you actually write any transform data -- always specify read-only access when possible.)
You can use the change version to filter out entities whose transforms have not changed since the last time a system ran. Implement change filtering using one of the following:
-
ArchetypeChunk.DidChange in an IJobChunk job.
Note that change versions are stored at the chunk level. Thus when you use change filtering, the query system excludes or includes whole chunks not individual entities.
GetChangeVersion<T>(SharedComponentTypeHandle<T>)
Gets the change version number assigned to the specified type of shared component in this chunk.
public readonly uint GetChangeVersion<T>(SharedComponentTypeHandle<T> chunkSharedComponentData) where T : struct, ISharedComponentData
Parameters
An object containing type and job safety information. To create this object, call ComponentSystemBase.GetSharedComponentTypeHandle. Pass the object to a job using a public field you define as part of the job struct.
Returns
Type | Description |
|---|---|
| uint | The current version number of the specified shared component, which is the version set the last time a system accessed a component of that type in this chunk with write privileges. Returns 0 if the chunk does not contain a shared component of the specified type. |
Remarks
Shared components behave differently than other types of components in terms of change versioning because changing the value of a shared component can move an entity to a different chunk. If the change results in an entity moving to a different chunk, then only the order version is updated (for both the original and the receiving chunk). If you change the shared component value for all entities in a chunk at once, the entities remain in their current chunk. The change version for that chunk is updated and the order version is unaffected.
GetChangeVersion(DynamicSharedComponentTypeHandle)
Gets the change version number assigned to the specified type of shared component in this chunk.
public readonly uint GetChangeVersion(ref DynamicSharedComponentTypeHandle typeHandle)
Parameters
An object containing type and job safety information. To create this object, call ComponentSystemBase.GetDynamicSharedComponentTypeHandle.
Returns
Type | Description |
|---|---|
| uint | The current version number of the specified shared component, which is the version set the last time a system accessed a component of that type in this chunk with write privileges. Returns 0 if the chunk does not contain a shared component of the specified type. |
Remarks
Shared components behave differently than other types of components in terms of change versioning because changing the value of a shared component can move an entity to a different chunk. If the change results in an entity moving to a different chunk, then only the order version is updated (for both the original and the receiving chunk). If you change the shared component value for all entities in a chunk at once, the entities remain in their current chunk. The change version for that chunk is updated and the order version is unaffected.