How to apply an arbitrary frame from an arbitrary AnimationClip

Question

I am working on a project with a rather unique combat system and am running into a wall when it comes to working with animations.

Specifically, I need to be able to play any animationclip at any time within the clip. This would be similar to using AnimationCurve.Evaluate, but for an entire animation clip, rather than a single curve. I looked at AnimationClip.SampleAnimation, but this didn't seem to work. As a general example, my use case looks along the lines of:

 AnimationClip clip;
 float time = 0f;
 
 void Update(){
      time += Time.deltaTime;
      clip.Sample(time); //This is where I'd like to sample the animation
 }

Obviously, the real script is far more elaborate and involves clips playing forward, backward, stopping, or jumping to arbitrary frames. This example script is essentially just the default behaviour of an animator, playing the clip immediately.

Another thing to note is that there may be a large number of animations involved, and adding them all to an animator controller is rather impractical. As such I'd like to stay as far away from mecanim and the animator controller or playables for these as possible. I've had mixed results with the legacy animation component, but would also rather avoid that due to the potential for it to be removed (the documentation states that it is only for backward compatibility).

All in all, it appears that much of the API is based on playing clips or blending between them, but I instead wish to sample the animations manually. I don't need crossfading, layers, states, or blending for this, just simple sampling as you would with an individual curve.

I know this is probably an odd request, but if anyone knows how to do this I would greatly appreciate any pointers in the right direction.

Thanks!

Answer 1

Best Answer

Answer by Ymrasu · Mar 08, 2019 at 12:20 AM

What I would do is use an Animator with an Animation Controller, as it seems Unity is pushing for that. You would simply load each of your clips as states, set the speed of each to zero (if you want to control them in script). A script could look something like this:

 Animator anim;
 float time = 0f;
 
 void Start() {
     anim = GetComponent<Animator>();
 }
 
 void Update(){
     time += Time.deltaTime;
     anim.Play("StateName", 0, time/lengthofclip);
 }

You would need to provide the lengthofclip, since that parameter is the percentage of the clip (zero to one). This means you could also do it by specific frame with frame/totalFrames.

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Zarenityx · Mar 08, 2019 at 06:13 AM 0

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Unfortunately, with the massive number of small animations involved, loading them all as states is quite impractical and would be prone to human error in keeping track of all of them. I really do need to be able to load in arbitrary clips, with little to no manual input beforehand. There doesn't seem to be a good way to, say, have a single state and change the motion that uses in code, so it looks like Animator Controllers are completely out.

I appreciate the answer regardless.

In all honesty, if I can't get this to work soon, I'll probably just end up writing a custom solution. I'm only animating transforms so it shouldn't be too bad. The Animator Controller is a great tool for fluid animations, but seems to be completely lacking in the lower-level functionality that I need with this project.

Ymrasu Zarenityx · Mar 08, 2019 at 03:01 PM 0

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Ok, looking back at AnimationClip, clip.SampleAnimation(gameObject, time); does the same thing. But I think the time is the length in seconds and not a percentage.

Zarenityx Ymrasu · Mar 08, 2019 at 04:43 PM 0

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I already mentioned in the original question that this wasn't working. I'm not sure why, it just hasn't been animating anything. This method seems to be exactly the solution, although I haven't been able to find how to use it.

EDIT: Ok, so my sincerest apologies for shooting this down. I had already tried to use this method, but finally it seems to work just fine. It just needed to be in LateUpdate() rather than Update().

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How to apply an arbitrary frame from an arbitrary AnimationClip

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