Add AnimationNode lifecycle callbacks

[RolandMQuiros]

Adds lifecycle script callbacks to AnimationNode so users can attach logic directly to animations.

Feature proposal: Fixes godotengine/godot-proposals#1462 (comment)

[fire]

Can you provide a small demo? I'm very interested in this.

Edited:

I noticed you had some problems with the static checks. Can walk you through the process.

[RolandMQuiros]

I'm throwing a demo project together now, hopefully will have it ready in a few hours.

Appreciate the support--I'm not sure what to make of the static check output, since it's showing me a diff on a whitespace.

[fire]

misc\scripts\clang_format.sh can help.

[RolandMQuiros]

I threw together a rough demo project with a simple character. WASD to move, space to jump, left click to attack: https://github.com/RolandMQuiros/animation-node-lifecycle-demo

I was having a rough time working through some UI bugs in 4.0, so I had to backport my changes to 3.2. You'll have to build Godot from this branch to run the demo: https://github.com/RolandMQuiros/godot/tree/animation-node-processing-3.2

If you look at the AnimationTree in the FSMCharacter scene, and click on one of the states, you'll see it has an fsm_node script attached, which exports an array of Resources. Each of those resources has a script attached that hooks into the lifecycle callbacks I implemented.

By organizing my code this way, I can write smaller and more reusable scripts that execute only when their attached AnimationNode is processing. For example, the Punch state doesn't have a Gravity behavior, so your dude will be suspended in midair while the animation plays. No need to explicitly check the Animator's current state in code.

Let me know if you have any issues getting the demo to run.

[RolandMQuiros]

Messed up a pull, sorry for the notifications. I didn't mean to add every dev as a reviewer, and I'm not sure how to undo that.

[fire]

I didn't have any time to review this. Try asking people in the discord.

Edited: Asked jfons

[fire]

To be ready for merging, the commits have to be either merged or there is a good reason to separate them for logical consistency.

Edited:

See https://docs.godotengine.org/en/stable/community/contributing/pr_workflow.html

[Rodeo-McCabe]

This is probably a solution to #28311

I would love to see this merged!

[TokageItLab]

The callback should be implemented as a signal, it is Godot's design concept. Also, it would be redundant to watch every AnimationNode's child class. So, I think "firing signals in AnimationNodeAnimation, AnimationNodeBlendTree, AnimationNodeBlendSpace2D and AnimationNodeBlendSpace1D which may will be called by AnimationNodeStateMachine" seems to be the right way to go.