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Game.Areas.CurrentDistrictSystem

Assembly: Assembly-CSharp.dll
Namespace: Game.Areas

Type: class

Base: GameSystemBase

Summary: CurrentDistrictSystem is a Unity ECS game system used by Cities: Skylines 2 to keep CurrentDistrict and BorderDistrict components up-to-date for world entities (objects and net elements). It listens to district updates reported by the UpdateCollectSystem and/or to entities that have the Updated tag and either CurrentDistrict or BorderDistrict components. The system uses spatial quad-tree search structures (area, object and net search trees) to find affected entities and schedules a set of Burst-compiled jobs to compute and write the correct district entities. When border/district changes may affect pathfinding (sub-lanes like car/pedestrian/parking), the system marks sub-lanes with a PathfindUpdated component via the ModificationBarrier's command buffer.

Fields

  • private UpdateCollectSystem m_UpdateCollectSystem
    Used to query whether districts have been updated and to get the list (bounds) of updated districts. This system triggers the parallel search when district bounds change.

  • private SearchSystem m_AreaSearchSystem
    Reference to the Area SearchSystem used to look up which district (area) contains a point by iterating area search tree items.

  • private Game.Objects.SearchSystem m_ObjectSearchSystem
    Reference to the object search tree for locating object entities that might need district updates.

  • private Game.Net.SearchSystem m_NetSearchSystem
    Reference to the net search tree for locating net edge entities (borders) that might need district updates.

  • private ModificationBarrier5 m_ModificationBarrier
    Barrier used to produce entity command buffers when scheduling parallel jobs that will add components (e.g., PathfindUpdated) on sub-lane entities. Ensures safe structural changes.

  • private EntityQuery m_CurrentDistrictQuery
    EntityQuery used to find chunks that have the Updated tag and either CurrentDistrict or BorderDistrict components. Used to run a chunk job that refreshes districts for those entities.

  • private TypeHandle __TypeHandle
    Internal struct holding component lookups and component type handles used across jobs and chunk processing. It is initialized in OnCreate/OnCreateForCompiler via __AssignHandles.

Properties

  • None (no public properties on this system).
    Internally the system uses component lookups and type handles stored in the TypeHandle field.

Constructors

  • public CurrentDistrictSystem()
    Default constructor. The system initializes and will set up its dependencies and queries in OnCreate. No custom construction logic beyond base initialization.

Methods

  • protected override void OnCreate() : System.Void
    Initializes references to dependent systems (UpdateCollectSystem, area/object/net SearchSystems, ModificationBarrier5) and builds the EntityQuery (m_CurrentDistrictQuery) that selects Updated entities that have CurrentDistrict or BorderDistrict components. Also called by Unity/ECS when the system is created.

  • protected override void OnUpdate() : System.Void
    Main update logic. Two primary flows:

  • If UpdateCollectSystem reports districtsUpdated: gather updated district bounds and perform:
    • FindUpdatedDistrictItemsJob (IJobParallelForDefer) — iterates object and net quad-trees to collect entities inside updated bounds that have CurrentDistrict/BorderDistrict and enqueues them.
    • CollectUpdatedDistrictItemsJob (IJob) — drains and sorts the native queue into a deduplicated NativeList.
    • FindDistrictParallelJob (IJobParallelForDefer) — for each entity in the update list, uses the area search tree to determine the new CurrentDistrict or BorderDistrict values, writes them back, and if needed marks sub-lanes with PathfindUpdated via the command buffer.
    • Sets up dependencies and readers on the various search systems and modification barrier so jobs run safely and structural changes are applied after jobs complete.
  • Independently, if there are any entities matched by m_CurrentDistrictQuery, the system schedules FindDistrictChunkJob (IJobChunk) to refresh CurrentDistrict/BorderDistrict for all matching chunks using the area search tree (non-incremental refresh for all entities in chunks).

The method carefully composes JobHandles so the search trees and update-collect data are read-safely while jobs run in parallel, disposing native containers at the appropriate job completions.

  • protected override void OnCreateForCompiler() : System.Void
    Helper called for compiler-generated initialization. Calls __AssignQueries and __TypeHandle.__AssignHandles to initialize ECS query & handle state used by jobs.

  • private void __AssignQueries(ref SystemState state) : System.Void
    (Basic stub in this generated code) Prepares and assigns any EntityQuery objects required by the system. In this decompiled/generator output it creates an EntityQueryBuilder and disposes it; real queries for runtime are created in OnCreate.

  • Nested job types and iterators (short summaries):

  • FindUpdatedDistrictItemsJob : IJobParallelForDefer
    Iterates a deferred array of Bounds2 (updated district bounds). Uses two quad-tree iterators (ObjectIterator and NetIterator) to find object and net entities intersecting each bound and enqueues matching entities that currently have CurrentDistrict or BorderDistrict components into a parallel NativeQueue.

    • ObjectIterator / NetIterator: per-tree iterators that check AABB intersection and HasComponent on entities before enqueuing.

  • CollectUpdatedDistrictItemsJob : IJob
    Drains the NativeQueue into a NativeList, sorts entity indices, and removes duplicates so the subsequent processing receives a compact, ordered list of unique entities to update.

  • FindDistrictParallelJob : IJobParallelForDefer
    For each entity in the update list, determines the containing district (for CurrentDistrict) or left/right districts for BorderDistrict using the AreaSearchTree. If a district change is detected it writes the new component values. If an entity's sub-lanes include lanes that require pathfinding updates, it adds a PathfindUpdated component to those sub-lane entities via the command buffer (unless the entity already has Updated or no sub-lane buffer).

    Important component lookups and buffer lookups are provided (transforms, edge geometry, district lookup, sub-lanes, triangles/nodes for point-in-triangle tests, lane types).

  • FindDistrictChunkJob : IJobChunk
    Runs on chunks selected by m_CurrentDistrictQuery to refresh CurrentDistrict and BorderDistrict components for all entities in the chunk using the area tree. This is the non-incremental path that ensures every matching entity gets a current district assignment (used when entities are flagged Updated).

  • DistrictIterator : INativeQuadTreeIterator<AreaSearchItem, QuadTreeBoundsXZ>
    Helper used by area-tree iterations to find which area/district a position falls into. It performs point-in-triangle tests against triangles stored on the area entity to identify the correct area entity result.

  • TypeHandle
    Auto-generated container for ComponentLookup, BufferLookup and ComponentTypeHandle instances. __AssignHandles fills these from a SystemState so jobs and chunk code can use them safely.

Usage Example

// CurrentDistrictSystem runs automatically in the world and updates components.
// As a modder you typically read CurrentDistrict or BorderDistrict components from entities.
// Example: reading CurrentDistrict for an entity:

Entity entity = /* some entity you know */;
if (EntityManager.HasComponent<CurrentDistrict>(entity))
{
    CurrentDistrict cur = EntityManager.GetComponentData<CurrentDistrict>(entity);
    Entity districtEntity = cur.m_District;
    // Use districtEntity (may be Entity.Null if not inside any district)
}

// If you need to trigger a manual refresh you can add Updated to an entity:
// (The system will pick up entities with Updated + CurrentDistrict/BorderDistrict)
EntityManager.AddComponent<Updated>(entity);

Notes and tips: - CurrentDistrictSystem depends on the game's area/object/net search trees. If you modify those trees or the district geometry, ensure you update the corresponding search system readers or synchronize with the UpdateCollectSystem. - Avoid performing structural changes that conflict with the system's scheduled command buffers. Use the provided ModificationBarrier when issuing parallel structural changes in jobs.