C# Entity

Entity class is one of the most important classes in the C# API. Using this class, you can write your scripts and do all sorts of things to in-game objects.

In order to write scripts for game objects, you need to create a class and derive it from Entity. Entity class allows you to override some important functions:

• OnCreate. It is called when an entity is spawned.

• OnDestroy. It is called when an entity is destroyed.

• OnUpdate. It is called on each frame and you can use its first parameter float timestamp which depends on the FPS.

• OnPhysicsUpdate. It is called each time the physics system is updated. It has the same arguments as OnUpdate function but the timestamp value is always the same and it does not depend on the FPS. Currently, timestamp is always 0.00833 ms (120 FPS).

• OnEvent. It is called each time an event is triggered. It receives an Event object as its first parameter.

Note

Physics callbacks receive two Entity objects. The first one is the owner of a callback, so that you can use it in lambdas and don’t need to worry about capturing it. The second one is an entity it collided with.

Additionally, Collision callbacks receive a CollisionInfo as a third argument. It contains information about collision position, normal, impulse, and force.

Entity class:

public class Entity
{
    public GUID ID { get; private set; }

    public virtual void OnCreate() { }
    public virtual void OnDestroy() { }
    public virtual void OnUpdate(float ts) { }
    public virtual void OnPhysicsUpdate(float ts) { }
    public virtual void OnEvent(Event e) { }

    public Entity Parent;
    public Entity[] Children;

    public Transform WorldTransform;
    public Vector3 WorldLocation;
    public Rotator WorldRotation;
    public Vector3 WorldScale;

    // Relative to a `Parent` entity if it is present
    public Transform RelativeTransform;
    public Vector3 RelativeLocation;
    public Rotator RelativeRotation;
    public Vector3 RelativeScale;

    public T AddComponent<T>() where T : Component, new();
    public bool HasComponent<T>() where T : Component, new();
    public bool HasComponent(Type type);
    public T GetComponent<T>() where T : Component, new();

    public GUID GetID() { return ID; }

    public Vector3 GetForwardVector();
    public Vector3 GetRightVector();
    public Vector3 GetUpVector();

    // Even though `OnDestroy` function is triggered immediately,
    // an entity and its data are deleted from memory at the beginning of the next frame
    public void Destroy();

    // Checks if a mouse is hovered over an entity
    // It checks if an entity would be hovered if a mouse was at the given coordinates.
    public bool IsMouseHovered() { return IsMouseHovered_Native(ID); }

    // Checks if a mouse is hovered over an entity
    // It checks if an entity would be hovered if a mouse was at the given coordinates.
    // @ mouseCoord. Mouse coord within a viewport
    public bool IsMouseHovered(ref Vector2 mouseCoord);

    // Use this function to be notified when an entity begins colliding with another one.
    // `Entity` object is passed to callbacks so that you have information with which entity collision happened.
    public void AddCollisionBeginCallback(Action<Entity, Entity, CollisionInfo> callback);

    public void RemoveCollisionBeginCallback(Action<Entity, Entity, CollisionInfo> callback);

    // Same as for `AddCollisionBeginCallback` but this one is triggered when a collision ends
    public void AddCollisionEndCallback(Action<Entity, Entity, CollisionInfo> callback);

    public void RemoveCollisionEndCallback(Action<Entity, Entity, CollisionInfo> callback);

    // Same as for `AddCollisionBeginCallback`
    public void AddTriggerBeginCallback(Action<Entity> callback);

    public void RemoveTriggerBeginCallback(Action<Entity> callback);

    // Same as for `AddCollisionEndCallback`
    public void AddTriggerEndCallback(Action<Entity> callback);

    public void RemoveTriggerEndCallback(Action<Entity> callback);

    // Returns the name of an entity
    public override string ToString();

    public Entity GetChildrenByName(string name);

    // Use this function to spawn new entities in a scene
    static public Entity SpawnEntity(string name = "");
}