/// <summary>
/// Gets the value of a singleton component.
/// </summary>
/// <typeparam name="T">The <see cref="IComponentData"/> subtype of the singleton component.</typeparam>
/// <returns>The component.</returns>
/// <seealso cref="EntityQuery.GetSingleton{T}"/>
public static T GetSingleton <T>(this ComponentSystemBase sys) where T : class, IComponentData
{
var type = ComponentType.ReadOnly <T>();
var query = sys.GetSingletonEntityQueryInternal(type);
return(query.GetSingleton <T>());
}
/// <summary>
/// Sets the value of a singleton component.
/// </summary>
/// <param name="value">A component containing the value to assign to the singleton.</param>
/// <typeparam name="T">The <see cref="IComponentData"/> subtype of the singleton component.</typeparam>
/// <seealso cref="EntityQuery.SetSingleton{T}"/>
public static void SetSingleton <T>(this ComponentSystemBase sys, T value) where T : class, IComponentData
{
var type = ComponentType.ReadWrite <T>();
var query = sys.GetSingletonEntityQueryInternal(type);
query.SetSingleton(value);
}
/// <summary>
/// Checks whether a singelton component of the specified type exists.
/// </summary>
/// <typeparam name="T">The <see cref="IComponentData"/> subtype of the singleton component.</typeparam>
/// <returns>True, if a singleton of the specified type exists in the current <see cref="World"/>.</returns>
public static bool HasSingleton <T>(this ComponentSystemBase sys) where T : class, IComponentData
{
var type = ComponentType.ReadOnly <T>();
var query = sys.GetSingletonEntityQueryInternal(type);
return(query.CalculateEntityCount() == 1);
}
