Spine 4.3 limit animation FPS in multithreaded environment

linhan

Is there any way to lock down the animation frame rate when things are multithreaded by spine 4.3?

So the SkeletonAnimationFixedTimestep example only works on the main thread right now, which means we can't really limit the animation FPS in a multithreaded setup. Does the new version offer any solution for this?

Harald

@linhan I'm afraid to say that this is not as easy and cleanly possible currently with threading enabled.

What is basically required is:

Set updateMode to UpdateMode.Nothing on frames without a fixed-timestep update.
Restore the previous updateMode on update frames.
Use a cumulated delta time (frames * frameDeltaTime) at the threaded animation update.
Clear requiresMeshBufferAssignmentMainThread when worker mesh generation is skipped.

While the first two items can be set more easily from an external component, items 3 and 4 require at least a subclass of SkeletonRenderer and SkeletonAnimation, which is somewhat of an unclean solution especially just for resetting requiresMeshBufferAssignmentMainThread.

We will have a look at how we can improve the situation to allow for easier threaded update-skipping. We will get back to you once we have a solution to offer.

Harald

@linhan Sorry for the delay! Unfortunately a clean suits-all API change or implementation has not been added yet.

Nevertheless, you could use a script like the following to set the SkeletonAnimation.UpdateMode to UpdateMode.OnlyAnimationStatus (this will skip events) or UpdateMode.OnlyEventTimelines to raise events during being "disabled". While this is not 100% free, it saves the majority of the update cost.

using Spine.Unity;
using UnityEngine;

public class FixedTimestepSkeletonAnimation : MonoBehaviour {
	#region Inspector
	public SkeletonAnimation skeletonAnimation;

	[Tooltip("The duration of each frame in seconds. For 12 fps: enter '1/12' in the Unity inspector.")]
	public float frameDeltaTime = 1 / 15f;

	[Header("Advanced")]
	[Tooltip("The maximum number of fixed timesteps. If the game framerate drops below the If the framerate is consistently faster than the limited frames, this does nothing.")]
	public int maxFrameSkip = 4;

	[Tooltip("If enabled, the Skeleton mesh will be updated only on the same frame when the animation and skeleton are updated. Disable this or call SkeletonAnimation.LateUpdate yourself if you are modifying the Skeleton using other components that don't run in the same fixed timestep.")]
	public bool frameskipMeshUpdate = true;

	[Tooltip("This is the amount the internal accumulator starts with. Set it to some fraction of your frame delta time if you want to stagger updates between multiple skeletons.")]
	public float timeOffset;
	#endregion

	float accumulatedTime = 0;

	void OnValidate () {
		skeletonAnimation = GetComponent<SkeletonAnimation>();
		if (frameDeltaTime <= 0) frameDeltaTime = 1 / 60f;
		if (maxFrameSkip < 1) maxFrameSkip = 1;
	}

	void Awake () {
		accumulatedTime = timeOffset;
	}

	void Update () {
		accumulatedTime += Time.deltaTime;

		float frames = 0;
		while (accumulatedTime >= frameDeltaTime) {
			frames++;
			if (frames > maxFrameSkip) break;
			accumulatedTime -= frameDeltaTime;
		}

		if (frames > 0) {
			skeletonAnimation.UpdateMode = UpdateMode.FullUpdate;
		}
		else {
			skeletonAnimation.UpdateMode = UpdateMode.OnlyAnimationStatus;
			//skeletonAnimation.UpdateMode = UpdateMode.OnlyEventTimelines;
		}
	}
}