For blending non-numeric value/bezier tracks the weights should be store separate from the key values

[TokageItLab]

Describe the project you are working on

Stabilize Godot animation system

Describe the problem or limitation you are having in your project

In the old AnimationTree this was not working correctly to begin with, but with the integration of the blend application process by AnimationMixer, the problem surfaced as godotengine/godot#82949.

I sent godotengine/godot#83030 as a workaround, but it is not the correct fix. It only applies the last processed one first.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

Allows non-numeric values to blend correctly.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Correct fix

For discrete values, it is possible to blend the weights of consecutive values from 0 to 1 in a similar way to Boolean values, giving priority to the one with the highest weight.

For example, suppose that the iterates stack image paths and weights as following:

weights: [
  {
    resource: "Image1.tres",
    weight: 0.3
  },
  {
    resource: "Image2.tres",
    weight: 0.3
  },
  {
    resource: "Image3.tres",
    weight: 0.4
  },
  {
    resource: "Image1.tres",
    weight: 0.2
  }
]

In this case, the final value with the highest weight is Image1.tres: 0.3 + 0.2 = 0.5. Thus, for non-numeric values, we can manage the weights and values in pairs to achieve the correct blending.

Also, we should salvage the godotengine/godot#49411 in order to share a blending process for BezierTrack.

If this enhancement will not be used often, can it be worked around with a few lines of script?

Nope

Is there a reason why this should be core and not an add-on in the asset library?

This is fixing the core feature