### SystemBuilder.setup Method

Source: https://nsstc.github.io/sim-ecs/classes/SystemBuilder

Adds a setup function that is called when the system is instantiated, for example, on a new world run. This method returns the SystemBuilder instance for chaining.

```TypeScript
setup(
  fn: TSystemFunction<Readonly<PARAMDESC>>,
) => SystemBuilder<Readonly<PARAMDESC>>
```

--------------------------------

### SystemBuilder.withSetupFunction Method

Source: https://nsstc.github.io/sim-ecs/classes/SystemBuilder

Adds a setup function that executes during system instantiation, such as at the start of a new world run. Returns the SystemBuilder for fluent chaining.

```TypeScript
withSetupFunction(
  fn: TSystemFunction<Readonly<PARAMDESC>>,
): SystemBuilder<Readonly<PARAMDESC>>
```

--------------------------------

### Build and Run Pong Example

Source: https://nsstc.github.io/sim-ecs/index

Builds and runs the 'pong' example, a full game demonstrating all sim-ecs features in the browser. It includes components, systems, states, and prefabs.

```bash
$cd examples/pong && npm install && npm run start
```

--------------------------------

### ISystemBuilder.withSetupFunction() Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISystemBuilder

Adds a setup function to the system. This function is executed once when the system is initialized, typically at the start of a new simulation or world instance.

```TypeScript
withSetupFunction(
  fn: TSystemFunction<Readonly<PARAMDESC>>,
): ISystemBuilder<Readonly<PARAMDESC>>
```

--------------------------------

### Run Counter Example

Source: https://nsstc.github.io/sim-ecs/index

Executes the 'counter' example provided with sim-ecs. This example is minimal and demonstrates basic functionality by incrementing a number.

```bash
$npm run example-counter
```

--------------------------------

### Run Events Example

Source: https://nsstc.github.io/sim-ecs/index

Runs the 'events' example, showcasing the use of the event bus for writing and reading events. It prints a message every second.

```bash
$npm run example-events
```

--------------------------------

### RuntimeWorld: prepare method

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Prepares the simulation world for execution, performing necessary setup operations.

```TypeScript
prepare(): Promise<void>
```

--------------------------------

### IRuntimeWorld Methods

Source: https://nsstc.github.io/sim-ecs/interfaces/IRuntimeWorld

This section outlines the methods available on the IRuntimeWorld interface. These include querying entities, getting resources, checking for entities and resources, replacing systems, refreshing entity registrations, and managing the world's lifecycle (start, step, stop).

```TypeScript
getEntities(query?: Readonly<IEntitiesQuery>): IterableIterator<IEntity>;
getGroupEntities(groupHandle: number): IterableIterator<IEntity>;
getResource<T extends object>(type: TTypeProto<T>): T;
getResources(
types?: readonly TExistenceQueryParameter<any>[],
): IterableIterator<object>;
hasEntity(entity: Readonly<IEntity>): boolean;
hasResource<T extends object>(type: T | TTypeProto<T>): boolean;
hmrReplaceSystem(newSystem: ISystem): void;
refreshEntityQueryRegistration(entity: Readonly<IEntity>): void;
replaceResource<T extends object>(
obj: T | TTypeProto<T>,
...args: readonly unknown[],
): Promise<void>;
save(options?: Readonly<ISerDeOptions<TSerializer>>): ISerialFormat;
start(): Promise<void>;
step(): Promise<void>;
stop(): void;
```

--------------------------------

### Install sim-ecs with npm

Source: https://nsstc.github.io/sim-ecs/index

Installs the sim-ecs package using npm. This is the standard way to add the library to your project for use in Node.js or browser environments.

```bash
$npm install sim-ecs
```

--------------------------------

### RuntimeWorld: start method

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Starts the continuous execution of the simulation world. The returned Promise resolves when the execution terminates.

```TypeScript
start(): Promise<void>
```

--------------------------------

### Set and Get Resources (JavaScript)

Source: https://nsstc.github.io/sim-ecs/index

Demonstrates how to add and retrieve resources from the world. Resources are objects that hold specific data, such as the start DateTime.

```javascript
// this call implicitely creates a new object of type Date. You can also pass an instance instead.
// you can pass arguments to the constructor by passing them as additional parameters here
prepWorld.addResource(Date);
console.log(world.getResource(Date).getDate());
```

--------------------------------

### Prepare Runtime World

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Asynchronously prepares a runtime environment from the current `PreptimeWorld`. Optional preparation options can be passed to customize the runtime setup.

```TypeScript
prepareRun(
options?: Readonly<Partial<IPreptimeOptions>>,
): Promise<IRuntimeWorld>
```

--------------------------------

### ISystemBuilder.setup() Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISystemBuilder

An alias for the withSetupFunction method, the setup method accepts a system function that is invoked when the system is instantiated, typically at the beginning of a new world run.

```TypeScript
setup(
  fn: TSystemFunction<Readonly<PARAMDESC>>,
): ISystemBuilder<Readonly<PARAMDESC>>
```

--------------------------------

### start - sim-ecs

Source: https://nsstc.github.io/sim-ecs/interfaces/IRuntimeWorld

Initiates continuous execution of the world's systems. The returned Promise resolves once the execution is terminated.

```TypeScript
start(): Promise<void>
```

--------------------------------

### Run System Error Example

Source: https://nsstc.github.io/sim-ecs/index

Executes the 'system-error' example, demonstrating how sim-ecs handles errors using its event system. Errors are caught and handled without aborting execution.

```bash
$npm run example-system-error
```

--------------------------------

### SimECS System Creation and Management

Source: https://nsstc.github.io/sim-ecs/classes/SerDe

Utilities for creating, querying, and managing systems within SimECS. This includes getting system run parameters and swapping systems during runtime.

```TypeScript
createSystem
getQueriesFromSystem
getSystemRunParameters
hmrSwapSystem
```

--------------------------------

### State create Method

Source: https://nsstc.github.io/sim-ecs/classes/State

Executes tasks when the state is created within the PDA. This method implements the IState.create interface, handling initial setup for the state.

```TypeScript
create(_actions: Readonly<ITransitionActions>): void | Promise<void>
```

--------------------------------

### Get All Resources

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Retrieves all resources currently stored within the world. This is particularly useful for debugging purposes. It accepts an optional array of existence query parameters.

```TypeScript
getResources: (  
this: PreptimeWorld | RuntimeWorld,
types?: readonly TExistenceQueryParameter<any>[]
) => IterableIterator<object>
```

--------------------------------

### Create Prepare-Time World (JavaScript)

Source: https://nsstc.github.io/sim-ecs/index

Initializes a prepare-time world for simulation setup. This world is used for defining and preparing all simulation elements before execution.

```javascript
const prepWorld = buildWorld().build();
```

--------------------------------

### Configuration and Initialization in SimECS

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

This snippet covers the configuration options and initialization process for SimECS, including setting up the world and its components.

```TypeScript
interface IRuntimeWorldInitConfig {
  // ...
}

class WorldBuilder {
  static create(config?: IRuntimeWorldInitConfig): WorldBuilder;
  build(): World;
}

// Example initialization:
const worldConfig = {
  // ...
};
const world = WorldBuilder.create(worldConfig).build();
```

--------------------------------

### PreptimeWorld Constructor

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Initializes a new instance of the PreptimeWorld class. It can optionally accept a name, configuration object, and initial data.

```TypeScript
constructor(
name?: string,
$config?: Partial<IPreptimeWorldConfig>,
$data?: Partial<IPreptimeData>
): PreptimeWorld
```

--------------------------------

### Start sim-ecs Simulation

Source: https://nsstc.github.io/sim-ecs/index

Starts the simulation loop for sim-ecs. The simulation runs based on the provided world data. It includes basic error handling for non-fatal errors and logs completion.

```JavaScript
runWorld.start()
    .catch(console.error)
    .then(() =>console.log('Finished.'));
```

--------------------------------

### World Builder and Configuration

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

Interfaces for building and configuring worlds, including runtime initialization options.

```Rust
WorldBuilder
IWorld
IWorldBuilder
IRuntimeWorld
IRuntimeWorldData
IRuntimeWorldInitConfig
IRuntimeWorldInitData
IImmutableWorld
IMutableWorld
IPreptimeWorld
IPreptimeWorldConfig
IPreptimeData
IPreptimeOptions
IObjectRegistrationOptions
```

--------------------------------

### World Building and System Creation

Source: https://nsstc.github.io/sim-ecs/interfaces/IImmutableWorld

Utilities for constructing and configuring SimECS worlds and systems. This includes building worlds from configurations, creating new systems, and managing system execution.

```Rust
buildWorld()
createSystem()
getQueriesFromSystem()
getSystemRunParameters()

```

--------------------------------

### Get Resource - sim-ecs RuntimeWorld

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Retrieves a stored resource by its type. Implements IRuntimeWorld.getResource.

```TypeScript
getResource: <T extends object>(this: RuntimeWorld, type: TTypeProto<T>) => T = getResource
// Get a resource which was previously stored
// Implementation of IRuntimeWorld.getResource
// Defined in src/world/runtime/runtime-world.ts:399
```

--------------------------------

### System Creation and Execution

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

Utilities for creating, configuring, and running systems within the ECS framework, including parameter handling and error management.

```Rust
createSystem()
getQueriesFromSystem()
getSystemRunParameters()
hmrSwapSystem()
SystemBuilder
SystemError
ISystem
ISystemActions
ISystemBuilder
ISystemError
ISystemResource
TSystemFunction
TSystemParameter
TSystemParameterDesc
TExecutionFunction
```

--------------------------------

### Get Resource in sim-ecs

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorld

Retrieves a previously stored resource based on its type. Inherited from IImmutableWorld.

```TypeScript
getResource<T extends object>(type: TTypeProto<T>): T
```

--------------------------------

### World and System Configuration

Source: https://nsstc.github.io/sim-ecs/interfaces/IImmutableWorld

Provides interfaces and types for configuring worlds and systems, including access descriptors, query descriptors, and options for registration and initialization.

```Rust
IAccessDescriptor
IAccessQuery
IComponentsQuery
IComponentsQueryDescriptor
IDeserializerOutput
IEntitiesQuery
IEntitiesQueryDescriptor
IEntity
IEntityBuilder
IEventBus
IEventMap
IExistenceDescriptor
IImmutableWorld
IIStateProto
IMutableWorld
IObjectRegistrationOptions
IPipeline
IPreptimeData
IPreptimeOptions
IPreptimeWorld
IPreptimeWorldConfig
IPushDownAutomaton
IQuery
IQueryDescriptor
IReadOnlyEntity
IResourceRegistrationOptions
IRuntimeWorld
IRuntimeWorldData
IRuntimeWorldInitConfig
IRuntimeWorldInitData
IScheduler
ISerDe
ISerDeDataSet
ISerDeOperations
ISerDeOptions
ISerialFormat
IStage
IState
IStateProto
ISyncPoint
ISyncPointPrefab
ISystem
ISystemActions
ISystemBuilder
ISystemError
ISystemResource
ITransitionActions
IWorld
IWorldBuilder

```

--------------------------------

### Get Existing Runtime Worlds

Source: https://nsstc.github.io/sim-ecs/interfaces/IPreptimeWorld

Retrieves a list of RuntimeWorlds that have been generated from this PreptimeWorld. This method is defined in `preptime-world.spec.ts`.

```TypeScript
getExistingRuntimeWorlds(): readonly IRuntimeWorld[]
```

--------------------------------

### Get Resources - sim-ecs RuntimeWorld

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Retrieves all resources stored in the world, useful for debugging. Implements IRuntimeWorld.getResources.

```TypeScript
getResources: (  
this: PreptimeWorld | RuntimeWorld,  
types?: readonly TExistenceQueryParameter<any>[],  
) => IterableIterator<object> = getResources
// Get all resources stored in this world. Useful for debugging
// Implementation of IRuntimeWorld.getResources
// Defined in src/world/runtime/runtime-world.ts:400
```

--------------------------------

### SimECS Commands and Queries

Source: https://nsstc.github.io/sim-ecs/interfaces/ISystemActions

Provides functions for interacting with the ECS world, such as getting entities, resources, and querying components.

```Rust
commands
currentState
getEntities
getResource
hasResource
queryComponents
queryEntities
Read
ReadEntity
ReadEvents
ReadOptional
ReadResource
Storage
With
Without
WithoutTag
WithTag
Write
WriteEvents
WriteOptional
WriteResource
```

--------------------------------

### sim-ecs: System Creation and Configuration

Source: https://nsstc.github.io/sim-ecs/classes/SyncPoint

Functions for creating and configuring systems within the sim-ecs framework. This includes creating new systems, defining their scheduling algorithms, and retrieving query information.

```TypeScript
createSystem(config: ISystemBuilder): ISystem
defaultSchedulingAlgorithm: TSchedulingAlgorithm
defaultStageSchedulingAlgorithm: TStageSchedulingAlgorithm
getQueriesFromSystem(system: ISystem): IQueryDescriptor[]
```

--------------------------------

### sim-ecs: Utility Functions and Markers

Source: https://nsstc.github.io/sim-ecs/interfaces/IQuery

This snippet includes utility functions for managing ECS worlds and sync points, as well as various marker types used internally by the sim-ecs library. These utilities facilitate common operations like world creation, system registration, and synchronization.

```C#
Actions
CIdMarker
CMarkerSeparator
CRefMarker
CResourceMarker
CResourceMarkerValue
CTagMarker
addSyncPoint
addWorld
buildWorld
clearRegistry
createSystem
defaultSchedulingAlgorithm
defaultStageSchedulingAlgorithm
getEntity
getQueriesFromSystem
getSyncPoint
getSystemRunParameters
getWorld
getWorlds
hmrSwapSystem
queryComponents
queryEntities
registerEntity
removeSyncPoint
removeWorld
unregisterEntity
unregisterEntityId
```

--------------------------------

### Get Existing Runtime Worlds

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Returns a read-only array of `IRuntimeWorld` instances that have been generated from the current `PreptimeWorld`.

```TypeScript
getExistingRuntimeWorlds(): readonly IRuntimeWorld[]
```

--------------------------------

### Get Existing Runtime Worlds

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Retrieves existing runtime worlds. This method is part of the IPreptimeWorld interface.

```TypeScript
getExistingRuntimeWorlds: () => RuntimeWorld[]
```

--------------------------------

### System Creation and Execution in SimECS

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

This snippet explains how to define and run systems in SimECS. Systems are functions that operate on entities and resources. It covers system creation, defining dependencies, and execution.

```TypeScript
class SystemBuilder {
  static create<T>(fn: TSystemFunction<T>): SystemBuilder;
}

// Example system:
const movementSystem = SystemBuilder.create((world: IMutableWorld) => {
  const entities = world.getEntities();
  for (const entity of entities) {
    // Update entity position
  }
});

world.addSystem(movementSystem);
world.runSystems();
```

--------------------------------

### ECS System Creation and Configuration

Source: https://nsstc.github.io/sim-ecs/interfaces/IRuntimeWorld

Details the creation and configuration of systems within the sim-ecs framework. This includes functions for creating new systems, defining their run parameters, and swapping systems during runtime (hot module replacement).

```TypeScript
createSystem
getQueriesFromSystem
getSystemRunParameters
hmrSwapSystem
```

--------------------------------

### Get Group Entities - sim-ecs RuntimeWorld

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Retrieves all entities associated with a specific group handle. Implements IRuntimeWorld.getGroupEntities.

```TypeScript
getGroupEntities: (  
this: PreptimeWorld | RuntimeWorld,  
groupHandle: number,  
) => IterableIterator<IEntity> = getGroupEntities
// Get all entities associated with a group
// Implementation of IRuntimeWorld.getGroupEntities
// Defined in src/world/runtime/runtime-world.ts:374
```

--------------------------------

### create Method

Source: https://nsstc.github.io/sim-ecs/interfaces/IState

The create method is called to run tasks when a state is initially created within the PDA. It accepts transition actions and may return a promise.

```TypeScript
create(actions: Readonly<ITransitionActions>): void | Promise<void>
```

--------------------------------

### PushDownAutomaton State Accessor

Source: https://nsstc.github.io/sim-ecs/classes/PushDownAutomaton

Gets the current state of the PushDownAutomaton. The state is read-only and can be of type T or undefined. This is an implementation of IPushDownAutomaton.state.

```TypeScript
pda.state
```

--------------------------------

### Get Group Entities in sim-ecs

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorld

Retrieves all entities associated with a specific group, identified by its handle. Inherited from IImmutableWorld.

```TypeScript
getGroupEntities(groupHandle: number): IterableIterator<IEntity>
```

--------------------------------

### TypeScript Method: prepareRun

Source: https://nsstc.github.io/sim-ecs/interfaces/IPreptimeWorld

Prepares the world for runtime execution, returning a Promise that resolves to the IRuntimeWorld. Accepts optional preptime options.

```TypeScript
prepareRun(
options?: Readonly<Partial<IPreptimeOptions>>,
): Promise<IRuntimeWorld>
```

--------------------------------

### SimECS Commands

Source: https://nsstc.github.io/sim-ecs/interfaces/ITransitionActions

Provides functions for interacting with the SimECS world, such as flushing commands, getting entities, and managing state.

```typescript
flushCommands()
currentState()
getEntities()
getResource()
hasResource()
popState()
pushState()
save()
```

--------------------------------

### State Proto and Transitions

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

Interfaces for state prototypes and actions related to state transitions.

```Rust
IIStateProto
IStateProto
ITransitionActions
```

--------------------------------

### Get Resource

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Retrieves a resource that has been previously stored in the world. This method is generic and requires the type of the resource to be specified.

```TypeScript
getResource: <T extends object>(this: RuntimeWorld, type: TTypeProto<T>) => T
```

--------------------------------

### TypeScript Array: length Property

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

The length property gets or sets the number of elements in an array. It is one greater than the highest index.

```TypeScript
length: number;
```

--------------------------------

### Tagging and Markers

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

Utilities for tagging entities and managing marker types within the ECS.

```Rust
CMarkerSeparator
CIdMarker
CRefMarker
CResourceMarker
CResourceMarkerValue
CTagMarker
TTag
```

--------------------------------

### Get Resources in sim-ecs

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorld

Retrieves all resources stored in the world, optionally filtered by type. Useful for debugging. Inherited from IImmutableWorld.

```TypeScript
getResources(types?: readonly TExistenceQueryParameter<any>[]): IterableIterator<object>
```

--------------------------------

### Get Group Entities in Sim-ECS World

Source: https://nsstc.github.io/sim-ecs/interfaces/IPreptimeWorld

Retrieves all entities associated with a specific group handle. This method is inherited from the IWorld interface.

```TypeScript
getGroupEntities(groupHandle: number): IterableIterator<IEntity>
```

--------------------------------

### SystemBuilder.build Method

Source: https://nsstc.github.io/sim-ecs/classes/SystemBuilder

Builds and returns the configured system as a read-only ISystem instance. This method finalizes the system construction process.

```TypeScript
build(): Readonly<ISystem<Readonly<PARAMDESC>>>
```

--------------------------------

### Get Entities by Group

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Fetches all entities associated with a given group handle. This method is defined within the `IPreptimeWorld` interface.

```TypeScript
getGroupEntities: (  
this: PreptimeWorld | RuntimeWorld,
groupHandle: number,
) => IterableIterator<IEntity>
```

--------------------------------

### Build Entity

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Provides a convenience builder for creating new entities. This method is part of the IPreptimeWorld interface.

```TypeScript
buildEntity: (this: IMutableWorld, uuid?: string) => IEntityBuilder = buildEntity
```

--------------------------------

### SimECS Entity Operations

Source: https://nsstc.github.io/sim-ecs/classes/SerDe

Functions for interacting with entities, such as getting, registering, and unregistering them. Also includes operations for entity builders and cloning.

```TypeScript
getEntity
registerEntity
unregisterEntity
unregisterEntityId
```

--------------------------------

### Sim-ECS System Creation and Execution

Source: https://nsstc.github.io/sim-ecs/interfaces/ISystemBuilder

This snippet covers the creation and execution of systems in sim-ecs. It includes functions for creating new systems, defining their execution parameters, and managing their scheduling.

```C#
namespace SimECS {
    public static class SystemFactory {
        public static ISystem createSystem(TSystemFunction function, TSystemParameter parameter) { /* ... */ }
        public static TSystemParameterDesc getSystemRunParameters(ISystem system) { /* ... */ }
        public static TSchedulingAlgorithm defaultSchedulingAlgorithm() { /* ... */ }
        // ... other system-related functions
    }
}
```

--------------------------------

### TypeScript: indexOf Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

Returns the index of the first occurrence of a value in an array, or -1 if it is not present. The search can optionally start from a specified fromIndex.

```typescript
indexOf(searchElement: TEntity, fromIndex?: number): number
```

--------------------------------

### TypeScript Array fill Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

Changes all elements in an array to a static value, from a start index to an end index. It returns the modified array.

```TypeScript
fill(value: TEntity, start?: number, end?: number): this
```

--------------------------------

### Resource Registration Methods (r, resource, withResource, withResources)

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

These methods are used to register resources within the simulation world. They accept resource definitions and optional registration options. 'r' and 'resource' are aliases for 'withResource'.

```TypeScript
r(
Resource: Readonly<TObjectProto>,
options?: Readonly<Partial<IResourceRegistrationOptions>>,
): IWorldBuilder;
```

```TypeScript
resource(
Resource: Readonly<TObjectProto>,
options?: Readonly<Partial<IResourceRegistrationOptions>>,
): IWorldBuilder;
```

```TypeScript
withResource(
Resource: Readonly<TObjectProto>,
options?: Readonly<Partial<IResourceRegistrationOptions>>,
): IWorldBuilder;
```

```TypeScript
withResources(Resources: readonly Readonly<TObjectProto>[]): IWorldBuilder;
```

--------------------------------

### SimECS Sync Point Management

Source: https://nsstc.github.io/sim-ecs/classes/SerDe

Functions for managing synchronization points within SimECS, including adding, getting, and removing sync points.

```TypeScript
addSyncPoint
getSyncPoint
removeSyncPoint
```

--------------------------------

### TypeScript: includes Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

Determines whether an array includes a certain element, returning true or false. It searches for an element starting from an optional fromIndex.

```typescript
includes(searchElement: TEntity, fromIndex?: number): boolean
```

--------------------------------

### System Creation and Management

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorld

Provides functions for creating and managing systems within the SimECS framework. This includes creating new systems and retrieving their run parameters.

```typescript
createSystem<T>(system: TSystemFunction<T>): void;
getSystemRunParameters<T>(system: TSystemFunction<T>): TSystemParameterDesc[];
```

--------------------------------

### IPreptimeOptions Properties: initialState

Source: https://nsstc.github.io/sim-ecs/interfaces/IPreptimeOptions

Details the 'initialState' property within the IPreptimeOptions interface. This property is of type IIStateProto and represents the starting state for the preptime execution.

```TypeScript
initialState: IIStateProto
```

--------------------------------

### Sim-ECS: System Execution and Parameters

Source: https://nsstc.github.io/sim-ecs/interfaces/ISyncPoint

Defines how systems are created, executed, and parameterized within Sim-ECS. Includes system builders, execution functions, and parameter descriptors for defining system behavior.

```C#
sim-ecs - v0.6.5
  * SystemBuilder
  * SystemError
  * ISystem
  * ISystemActions
  * ISystemBuilder
  * ISystemError
  * ISystemResource
  * ITransitionActions
  * TExecutionFunction
  * TSystemFunction
  * TSystemParameter
  * TSystemParameterDesc
  * createSystem
  * getSystemRunParameters
```

--------------------------------

### Get Resource by Type in Sim-ECS World

Source: https://nsstc.github.io/sim-ecs/interfaces/IPreptimeWorld

Retrieves a resource previously stored in the Sim-ECS world based on its type. This method is inherited from the IWorld interface.

```TypeScript
getResource<T extends object>(type: TTypeProto<T>): T
```

--------------------------------

### Get System Run Parameters

Source: https://nsstc.github.io/sim-ecs/functions/getSystemRunParameters

Retrieves the run parameters for a given system within the ECS world. This function is crucial for understanding how a system is configured and executed.

```typescript
getSystemRunParameters(
  system: Readonly<ISystem>,
  world: Readonly<IRuntimeWorld>,
): TSystemParameterDesc
```

--------------------------------

### sim-ecs: World Builder and Configuration

Source: https://nsstc.github.io/sim-ecs/classes/SyncPoint

Types for building and configuring worlds.

```TypeScript
WorldBuilder
IWorldBuilder
```

--------------------------------

### Get Entities - sim-ecs RuntimeWorld

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

Queries entities based on component combinations. Use getEntity() for single entity retrieval by ID. Implements IRuntimeWorld.getEntities.

```TypeScript
getEntities: (  
this: PreptimeWorld | RuntimeWorld,  
query?: Readonly<IEntitiesQuery>,  
) => IterableIterator<IEntity> = getEntities
// Query entities and find the ones with a certain combination of component. To get a single entity by ID, please use the global function `getEntity()`
// Implementation of IRuntimeWorld.getEntities
// Defined in src/world/runtime/runtime-world.ts:359
```

--------------------------------

### State Management with PushDownAutomaton in SimECS

Source: https://nsstc.github.io/sim-ecs/classes/RuntimeWorld

This section explains the PushDownAutomaton (PDA) for managing states within SimECS. It covers pushing and popping states, and how the PDA transitions between different states.

```TypeScript
class PushDownAutomaton {
  pushState<T>(state: T): void;
  popState(): void;
}

// Example usage:
const pda = new PushDownAutomaton();
pda.pushState('MainMenu');
// ... later
pda.popState();
```

--------------------------------

### Scheduling Configuration Methods

Source: https://nsstc.github.io/sim-ecs/interfaces/IWorldBuilder

Methods for configuring the scheduler and scheduling logic for the simulation world. This includes setting default schedulers and custom planners.

```TypeScript
withDefaultScheduler(scheduler: Readonly<IScheduler>): IWorldBuilder;
```

```TypeScript
withDefaultScheduling(planner: (root: ISyncPoint) => void): IWorldBuilder;
```

```TypeScript
withStateScheduler(
state: Readonly<IIStateProto>,
scheduler: Readonly<IScheduler>,
): IWorldBuilder;
```

```TypeScript
withStateScheduling(
state: Readonly<IIStateProto>,
planner: (root: ISyncPoint) => void,
): IWorldBuilder;
```

--------------------------------

### Get Entity by ID

Source: https://nsstc.github.io/sim-ecs/functions/getEntity

Retrieves a tracked entity by its unique string ID. Returns the entity if found, otherwise returns undefined. This function is defined in src/ecs/ecs-entity.ts.

```TypeScript
getEntity(id: string): undefined | IEntity
```

--------------------------------

### WorldBuilder Build

Source: https://nsstc.github.io/sim-ecs/classes/WorldBuilder

Constructs and returns the simulation world. This method finalizes the world building process and returns a PreptimeWorld instance.

```TypeScript
build(): PreptimeWorld
```

--------------------------------

### Add Resource

Source: https://nsstc.github.io/sim-ecs/classes/PreptimeWorld

Adds a resource of a specified type to the world and returns an instance of that resource. It accepts the resource type and constructor arguments.

```TypeScript
addResource: <T extends object>(
this: PreptimeWorld,
Type: T | TTypeProto<T>,
...args: readonly unknown[]
) => T | TTypeProto<T> = addResource
```

--------------------------------

### TypeScript Array lastIndexOf

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

Finds the last index of a specified element in an array. It searches backward from an optional starting index. Returns -1 if the element is not found.

```TypeScript
lastIndexOf(searchElement: TEntity, fromIndex?: number): number
```

--------------------------------

### sim-ecs: Resource and System Registration

Source: https://nsstc.github.io/sim-ecs/classes/SyncPoint

Types for registering resources and systems.

```TypeScript
SimECSSystemAddResourceEvent
SimECSSystemReplaceResourceEvent
```

--------------------------------

### SimECS World and System Management Functions

Source: https://nsstc.github.io/sim-ecs/classes/Query

This snippet outlines key functions for managing worlds and systems, including creation, addition, removal, and querying of entities and components.

```typescript
function addSyncPoint(world: IWorld, name: string)
function addWorld(world: IWorld)
function buildWorld(builder: IWorldBuilder): IWorld
function clearRegistry()
function createSystem(fn: TSystemFunction, parameters: TSystemParameter[]): ISystem
function getEntity(id: TEntityId): IEntity
function getQueriesFromSystem(system: ISystem): IQueryDescriptor[]
function getSyncPoint(name: string): ISyncPoint
function getSystemRunParameters(system: ISystem): TSystemParameterDesc[]
function getWorld(id: string): IWorld
function getWorlds(): IWorld[]
function hmrSwapSystem(oldSystem: ISystem, newSystem: ISystem)
function queryComponents(descriptor: IComponentsQueryDescriptor): TAccessQueryData
function queryEntities(descriptor: IEntitiesQueryDescriptor): TAccessQueryData
function registerEntity(entity: IEntity)
function removeSyncPoint(name: string)
function removeWorld(id: string)
function unregisterEntity(entity: IEntity)
function unregisterEntityId(id: TEntityId)
```

--------------------------------

### Stage Class Constructor

Source: https://nsstc.github.io/sim-ecs/classes/Stage

Initializes a new instance of the Stage class. This constructor is part of the core setup for managing stages within the sim-ecs pipeline.

```TypeScript
new Stage(): Stage
```

--------------------------------

### SimECS System Creation and Management

Source: https://nsstc.github.io/sim-ecs/classes/Scheduler

Details functions for creating and managing systems in SimECS. This includes creating new systems from functions, retrieving system run parameters, and swapping systems during runtime.

```TypeScript
export function createSystem(system: TSystemFunction): void;

export function getSystemRunParameters(system: ISystem): TSystemParameterDesc[];

export function hmrSwapSystem(oldSystem: ISystem, newSystem: ISystem): void;
```

--------------------------------

### IRuntimeWorldInitData Interface Definition

Source: https://nsstc.github.io/sim-ecs/interfaces/IRuntimeWorldInitData

Defines the structure for initial data required to set up a runtime world. It includes sets of entities, group information with entity links and next handle, and maps of resources.

```TypeScript
interface IRuntimeWorldInitData {
  entities: ReadonlySet<Readonly<IEntity>>;
  groups: {
    entityLinks: Map<number, ReadonlySet<Readonly<IEntity>>>;
    nextHandle: number;
  };
  resources: ReadonlyMap<object | TObjectProto, readonly unknown[]>;
}
```

--------------------------------

### TypeScript Array copyWithin Method

Source: https://nsstc.github.io/sim-ecs/interfaces/ISerialFormat

Copies a section of an array to another position within the same array. It returns the modified array. The target, start, and end parameters can be negative.

```TypeScript
copyWithin(target: number, start: number, end?: number): this
```