Game.Simulation.ObjectCollisionSystem

Assembly: Assembly-CSharp
Namespace: Game.Simulation

Type: class

Base: GameSystemBase

Summary:
ObjectCollisionSystem detects and resolves physical collisions between in-game objects (including vehicles and lane objects) using Unity DOTS/ECS jobs. It performs spatial queries against the game's net search tree, samples object transforms across frames to find intersections, enqueues detected collisions, and then resolves them by applying velocity/ angular changes and generating Impact / Damage / Destroy events. The system uses an EndFrameBarrier to emit event entities and synchronize command buffer execution.

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Fields

• private SimulationSystem m_SimulationSystem
  Reference to the SimulationSystem used for frame indexing and simulation timing.

• private Game.Net.SearchSystem m_NetSearchSystem
  Reference to the net search system used to perform spatial queries against network-related objects and lane objects.

• private EndFrameBarrier m_EndFrameBarrier
  Barrier system used to create a command buffer for producing event entities at the end of the frame.

• private EntityQuery m_ObjectQuery
  EntityQuery selecting objects considered for collision detection (requires UpdateFrame, Transform, Moving, TransformFrame and excludes deleted/temp/unspawned).

• private EntityQuery m_ConfigQuery
  EntityQuery used to fetch FireConfigurationData (used to update structural integrity data).

• private EntityArchetype m_EventImpactArchetype
  Archetype used to create Impact event entities.

• private EntityArchetype m_DamageEventArchetype
  Archetype used to create Damage event entities.

• private EntityArchetype m_DestroyEventArchetype
  Archetype used to create Destroy event entities.

• private EventHelpers.StructuralIntegrityData m_StructuralIntegrityData
  Helper storing structural integrity values (updated from configuration and used to compute damage thresholds).

• private TypeHandle __TypeHandle
  Generated container of type handles and component lookups used by the scheduled jobs (assigned at creation).

Properties

• None (this system exposes no public properties).

Constructors

• public ObjectCollisionSystem()
  Default preserved constructor. Initialization of fields is performed in OnCreate rather than the constructor.

Methods

• protected override void OnCreate()
  Initializes system references (SimulationSystem, NetSearchSystem, EndFrameBarrier), builds queries and archetypes, and prepares structural integrity helper. Registers the object query as required for update.

• protected override void OnUpdate()
  Main system update:

• Computes current transform frame indices based on SimulationSystem.frameIndex.
• Creates a NativeQueue to collect collisions detected by a parallel job (FindCollisionsJob).
• Schedules FindCollisionsJob (IJobChunk) that queries nearby objects via the net search tree and tests per-substep box/box intersections along object motion to find collision times and impact locations.
• Schedules ResolveCollisionsJob (IJob) that sorts collisions, filters duplicates, applies velocity/angular changes, creates Impact/Damage/Destroy events and updates components (Transform, Moving, TransformFrame) for involved entities.

• Ensures proper dependencies: passes net search tree reader handle, disposes the collision queue after the resolve job completes, adds net search tree reader and EndFrameBarrier producer handles, and sets base.Dependency.

• protected override void OnCreateForCompiler()
  Internal setup used by the generated code path / compiler support: assigns queries and type handles for the system.

• [MethodImpl(MethodImplOptions.AggressiveInlining)] private void __AssignQueries(ref SystemState state)
  Internal helper used by the generated code to initialize any queries used by the system (kept empty aside from a temporary builder in this implementation).

• Nested types (summaries):

• private struct Collision
  Small POD struct describing a detected collision: positions, rotations, impact location, involved entities, collision time and transform frame indices. Implements IComparable to sort by time.

• [BurstCompile] private struct FindCollisionsJob : IJobChunk
  Chunk job that:

  • Iterates entities matching m_ObjectQuery.
  • For each entity, constructs swept boxes between previous and current transform frames.
  • Uses a NetIterator (INativeQuadTreeIterator) to query nearby objects/lane objects from the net search tree.
  • Samples up to 16 substeps (interpolation fractions) and conducts box-box intersection tests to determine collision time and impact location.
  • Enqueues found Collision entries into a parallel NativeQueue.

• [BurstCompile] private struct ResolveCollisionsJob : IJob
  Single-threaded job that:

  • Converts the collision queue to an array and sorts collisions by time.
  • Skips collisions involving entities already processed in the same pass.
  • Computes point velocities, moments of inertia and angular velocity deltas.
  • Applies velocity/ angular changes to Moving components (or packages them into Impact events when the object isn't currently simulated as moving).
  • Creates Impact, Damage or Destroy event entities through an EntityCommandBuffer provided by the EndFrameBarrier.
  • Uses structural integrity values to determine damage amounts and whether an entity should be destroyed.

• private struct TypeHandle
  Generated structure holding all the Unity Entities type handles, ComponentLookup and BufferLookup objects used by the jobs. Provides __AssignHandles(ref SystemState) to initialize lookups from the current SystemState.

Usage Example

// From another system or mod initialization: get the system and let it run as part of the simulation.
var collisionSystem = World.GetOrCreateSystemManaged<Game.Simulation.ObjectCollisionSystem>();

// If you need to read collision-driven events, listen for Impact / Damage / Destroy events
// by querying entities with the corresponding components in a system that runs after
// EndFrameBarrier has produced them.

Notes: - The system relies heavily on Unity's DOTS (Entities, Jobs, Burst) and the game's net search tree to limit collision checks. - Collision detection uses conservative swept-box checks and substep interpolation (16 samples) to find approximate impact times and locations. - Events are emitted via an EndFrameBarrier command buffer to ensure safe structural changes at the proper point in the frame.