Important! Support for animation layers is experimental at the moment and should be treated as such. If you encounter any oddities or bugs, please add a new issue, describing the problem as clearly as possible.

When working with animation layers things get slightly more complex.

Tweener is designed to work similar to Maya, which means that

1. Each attribute is evaluated separately and works by on best layer basis. The best layer is the top-most selected layer on which the attribute exists and where the layer is is unlocked. Otherwise it searches down through the list of layers where a particular attribute is added, eventually ending up at the root aka BaseAnimation.

   This means that you may have a situation where different keys are added or modified on different layers. For example if you have translate XYZ on AnimLayer1, rotate XYZ on AnimLayer2, and only have selected AnimLayer2, then the translate keys on AnimLayer1 is still affected, because the translate attributes are not on AnimLayer2 and so the best layer for translate becomes AnimLayer1. You can only avoid this by locking all layers except for the one you wish to adjust. This is how Maya works and therefore how Tweener works as well.

2. Each attribute is only evaluating and modifying the animation curve on the best layer. In practice it means that Tweener does not blend between what you see on screen but rather blends between keys on the animation curve, specifically for the best layer.

   As an example, imagine you have an animation of a ball rolling along the floor on your BaseAnimation layer. Then add a new layer, AnimLayer1, and animate a jump. With AnimLayer1 selected, adjust an in-between on your jump using Tweener. You will see that Tweener only blends towards your jump keys, without blending in the keys for the roll, which are on the BaseAnimation layer.