I need to do processing on each animation frame. Favorite ways to do this?

dotted

I need to calculate on the fly the transforms for bones during animation, but googling

godot animation on each frame

isn't returning anything helpful.

cybereality

You could just have your script on the physics_process() or process(). I believe you can also animate functions, but I had issues with the interpolation. Not sure if I was calling it wrong, but you can add function calls to animation tracks (the feature is called "Call Method Track" so maybe look into that). Otherwise you could also use a Tween or a Timer and call a function to do the processing.

dotted

Already played with it (and posted a discussion to 'document' how to set it up; the docs are poor in this area) .Method track is only invoked on keyframes which is not useful in this case.

I am deforming polyline (in an animation) and the resulting transforms for a skeleton hierarchy matching the deformation cannot be modeled by linear interpolation of the bone node transforms between the keyframes. Animation interpolation (ie every option) is fine at the keyframes but diverge from them towards the mid point of the interpolation interval, the visual effect is Not Good.

A Tween doesn't address the issue for the same reason.

_process calls make the most sense since the model line2d is updated at video frame rates, not physics frames.

At the moment I am inclined to instrument the bones with a script just before the animation plays with the right data and allow the _process call to handle the changes.

... question when you set a script to an node already in a scene tree, does _ready() get called? i doubt i need to rely on it but the question arises from dynamically instrumenting nodes in this way.

xyz

@dotted said: ... question when you set a script to an node already in a scene tree, does _ready() get called?

No, but stript's _init() will be called.

cybereality

Yeah, so process() makes the most sense. However, my suggestion was to call a method from either the animation track or a tween (or a timer) not that the animation/tween would do the processing. The processing would happen on your custom function. But I think doing this is process is easier anyhow.

dotted

I scanned Tween and it seems like it's over head rather than help.

applying a script to the governing line2d and calling some processing in its _process call to tweak the armature seems the best way forward.

dotted

@xyz said:

@dotted said: ... question when you set a script to an node already in a scene tree, does _ready() get called?

No, but stript's _init() will be called.

k' thanks. init and ready aren't of much interest here but its good to know.

dotted

@xyz said:

@dotted said: ... question when you set a script to an node already in a scene tree, does _ready() get called?

No, but stript's _init() will be called.

It doesn't appear that adding a script to a node after it is in the scene tree adds in ( its newly bound?) _ready() call. Placing a break point has no effect.

var engine:ArmatureEngine = ArmatureEngine.new()
line2d.set_script(engine.get_script())
line2d.bone_chain  = fiber
line2d.distal_chain = distal

... func process(delta:float): var K:Array = bone_chain var D:Array = distal_chain

Solved by making Engine extend Node and simply adding it thus:

func _add_armature_engine(line2d:Line2D, fiber:Array, distal:Array):
	if fiber.size():
		var engine:ArmatureEngine = ArmatureEngine.new()
		engine.bone_chain   = fiber
		engine.distal_chain = distal
		line2d.add_child(engine)

func _remove_armature_engine(line2d:Line2D):
	var node:Node = line2d.get_node_or_null('ArmatureEngine')
	if node: node.queue_free()

It's a bit cleaner, as it is in effect a 'processing' node added on demand to do a job which is then removed when the task is over.

The animated line2d points are now used to calculate the transforms of the armature and the bones follow precisely the animated point movement.