Time and Fixed Updates

TimeService provides scaled and unscaled frame time, fixed-step time, totals, frame counters, and pause state. Axolotl2D registers it as a singleton so every scene and component reads the same clock.

Read frame time

Inject TimeService into a component:

public sealed class Lifetime(GameObject gameObject, TimeService time)
    : Component(gameObject)
{
    public override void Update(double deltaTime)
    {
        if (time.TotalTime > 30)
            GameObject.Destroy();
    }
}

The callback deltaTime matches TimeService.DeltaTime. The service also exposes UnscaledDeltaTime for UI, pause menus, and effects that should ignore game speed.

Scale or pause time

time.TimeScale = 0.5;
time.IsPaused = true;

TimeScale must be finite and at least zero. Pausing sets scaled DeltaTime to zero while UnscaledDeltaTime, input actions, rendering, and the unscaled clock continue. Set IsPaused to false from an input action to resume play.

Property	Contents
DeltaTime	Current frame duration after pause and time scale
UnscaledDeltaTime	Current wall-clock frame duration
FixedDeltaTime	Duration of the current fixed step
TotalTime	Accumulated scaled game time
UnscaledTotalTime	Accumulated wall-clock game time
FrameCount	Number of update frames
FixedFrameCount	Number of fixed steps

Configure fixed updates

Each scene owns its fixed-step settings:

public sealed class GameplayScene : BaseScene
{
    public GameplayScene()
    {
        FixedTimeStep = 1d / 60d;
        MaximumFixedStepsPerFrame = 8;
    }
}

Axolotl2D adds scaled frame time to the scene accumulator. A paused scene performs no fixed steps. Slow motion reduces the frequency of fixed steps in wall-clock time while each step still receives FixedTimeStep.

Each fixed phase runs in this order:

1. TimeService records the fixed step.
2. Active components receive FixedUpdate.
3. The scene receives FixedUpdate.
4. The scene removes objects queued for destruction.
5. PhysicsWorld advances and synchronizes transforms.
6. The scene dispatches physics contacts and removes objects destroyed by contact handlers.

Use FixedUpdate to apply forces and impulses. Read the resulting transform in Update or LateUpdate.