Same AnimationGroup can have different number of frames

Questions
1

Hi everyone,

I first noticed this in the Inspector:

Screenshot 2025-01-22 133328
Screenshot 2025-01-22 133328447×957 70.6 KB

The To-frame can be 72 or 144.

To reproduce, I need to reload the game. Then, whenever I play a walk animation before the screenshot animation, it is 144. If I play the screenshot animation immediately, it is 72. Once the game is running, the value remains the same.

I have also double checked:

// render loop
const debug = scene.getAnimationGroupByName("RollForwardAndStandWithAny");
if(debug) {
    console.log(debug.to); //either 72 or 144 as described above
}

Confirms what the Inspector shows. So it seems whatever happens, happens on load.

Load means SceneLoader.ImportMeshAsync and then grabbing the AnimationGroup.

Inspecting the loaded AnimationGroups, right after load, I see differences in fps:

  • In the 144 case: targetedAnimations of screenshot AnimationGroup has 60fps.
  • In the 72 case: targetedAnimations of screenshot AnimationGroup has 30fps.

How can the loading or playing of one animation, cause a not yet loaded animation to have a different number of frames / fps?

If there is no easy answer: Where does ImportMeshAsync actually create AnimationGroups from a GLB?

I got to the GLTFLoader which seems to be one place where fps are applied to animations. The fps value comes from a parent GLTFFileLoader from a “targetFps” property. This is 60 by default but can be set by an options parameter. But there I lose track. Nothing seems to access targetFps or the glTFFileLoader :dizzy_face:

Might be a dead end though because this does not make a difference:

BABYLON.SceneLoader.OnPluginActivatedObservable.addOnce(function (loader) {
  if(loader.name === "gltf") {
      loader.targetFps = 30;                                     
  }
});

Best wishes
Joe

2

It is tough to say without a simple repro :frowning: