Cannot override bone Transform in code when using AnimationTree, even Deterministic = false

[nagasawamaki]

Tested versions

v4.2.1.stable.official [b09f793]

System information

Godot v4.2.stable - Windows 10.0.19045 - Vulkan (Forward+)

Issue description

When using AnimationTree, I cannot override the bone transform in code.
Everytime it seems the AnimationTree will reset my overrided bone transform,
even I have checked Deterministic = false option, as stated in #87400 .

Steps to reproduce

Import a animated model and set up AnimationTree node and active it, also check Deterministic = false option .

write a script to override bone transform, like below:

func _physics_process(delta):
	test.get_node("Armature/Skeleton3D").set_bone_global_pose_override(b_idx, Transform3D(), 1)

No any effect.

Minimal reproduction project (MRP)

bone_transform_override.zip

[TokageItLab]

You should use set_bone_pose_rotation(). Also, as a specification, it cannot be overridden while the animation is playing although Deterministic = false. We are planning something like Bone Modification that can be blended with animation by reworking IK, but it is still in the planning stage.

[nagasawamaki]

You should use set_bone_pose_rotation(). Also, as a specification, it cannot be overridden while the animation is playing although Deterministic = false. We are planning something like Bone Modification that can be blended with animation by reworking IK, but it is still in the planning stage.

I have changed the function from test.get_node("Armature/Skeleton3D").set_bone_global_pose_override(b_idx, Transform3D(), 1) to test.get_node("Armature/Skeleton3D").set_bone_pose_rotation(b_idx, Quaternion()) but still no any effect.

Do you mean currently I cannot change the bone rotation by code when using with animationTree?

[TokageItLab]

See above. Animation values are applied after gdscript process().

Also, as a specification, it cannot be overridden while the animation is playing although Deterministic = false. We are planning something like Bone Modification that can be blended with animation by reworking IK, but it is still in the planning stage.

[KMouratidis]

@nagasawamaki does it work if you do the override in _process instead? E.g. this works for me:

extends Node3D

@onready var test : Node3D = $test2

func _process(delta):
	var b_idx = test.get_node("Armature/Skeleton3D").find_bone("Bone.001")
	test.get_node("Armature/Skeleton3D").set_bone_global_pose_override(b_idx, Quaternion())

Edit: Oh, it also works without process_priority too. But this does need the process priority:

extends Node3D

@onready var test = $test2

func _ready():
	process_priority = 1

func _process(delta):
	var b_idx = test.get_node("Armature/Skeleton3D").find_bone("Bone.001")
	test.get_node("Armature/Skeleton3D").set_bone_pose_rotation(b_idx, Quaternion())

[TokageItLab]

Oh, indeed, the main problem is that the CallbackModeProcess of the AnimationMixer does not match the process of the script.

However, even if they do match, it is not safe because the order in which the animation values are applied depends on the node order in SceneTree or process_priority as @KMouratidis said.

[KMouratidis]

See above. Animation values are applied after gdscript process().

That doesn't sound right to me.

All internal code should be called before GDScript, as seen here:

godot/scene/main/scene_tree.cpp

Lines 934 to 948 in 70ca659

	if (p_physics) {
	if (n->is_physics_processing_internal()) {
	n->notification(Node::NOTIFICATION_INTERNAL_PHYSICS_PROCESS);
	}
	if (n->is_physics_processing()) {
	n->notification(Node::NOTIFICATION_PHYSICS_PROCESS);
	}
	} else {
	if (n->is_processing_internal()) {
	n->notification(Node::NOTIFICATION_INTERNAL_PROCESS);
	}
	if (n->is_processing()) {
	n->notification(Node::NOTIFICATION_PROCESS);
	}
	}

And if I'm not mistaken, the actual updates DO happen in process/physics process, as seen here:

godot/scene/animation/animation_player.cpp

Lines 242 to 260 in 70ca659

	case NOTIFICATION_INTERNAL_PROCESS: {
	if (process_callback == ANIMATION_PROCESS_PHYSICS) {
	break;
	}
	if (processing) {
	_animation_process(get_process_delta_time());
	}
	} break;
	case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {
	if (process_callback == ANIMATION_PROCESS_IDLE) {
	break;
	}
	if (processing) {
	_animation_process(get_physics_process_delta_time());
	}
	} break;

So maybe the reason why it works in _process but not in _physics_process is because the order is:

1. Physics process internal: AnimationPlayer / AnimationTree sets bone data
2. Physics process gdscript: player overrides bone data
3. Process internal: AnimationPlayer / AnimationTree sets bone data, overriding the user's override
4. Process gdscript: overrides in here work

This explains why set_bone_global_pose_override in _physics_process doesn't work but _process works.

As for the reason this doesn't apply to set_bone_pose_rotation unless you set process_priority, I'm still unable to understand. :facepalm: I think this is because of the tree order processing, as mentioned in the comment above:

1. Player updates something at top node
2. Grandchild node goes over the above 4 steps

Which with process_priority=1 becomes:

1. Grandchild node goes over the above 4 steps
2. Player updates something at top node

And maybe overrides just overshadow all the other modifications?

[TokageItLab]

set_bone_global_pose_override - bone_pose_override was implemented to ignore process order for BoneModifications that need to be applied after Animation like IK or PhysicsBone, as hack, but the problem here would be that even if it did, it would not ignore the order for rendering server with skinning (and also maybe multi-threading will mess them up). I'm writing a proposal now to deprecate bone_pose_override in the future and instead have a cleaner control over process order for Animation.

[nagasawamaki]

@KMouratidis Thanks! It works when I put the code inside _process. And thanks for your detailed explanation about the running order inside Godot.

@TokageItLab Got it. Hope your proposal will be implemented soon. Thanks.