Y and Z Root Motion Switched

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1

Godot Version

4.6 Beta1

Question

I’m having a strange issue where my Z and Y axis appear to be flipped for the root motion of my animation. I made the animation in blender and I swear that I checked “+ Y UP” before exporting it. I’ve double checked it a dozen times now.

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Here is a video where I show the issue and that the root motion of the animation moves correctly in the animation player. In the video you can see that the model moves in the Y direction and clips through the wall. Then, I uncomment two lines of code: one setting the Y velocity to the root Z velocity and the other setting Z velocity to 0. Now the model moves to the top of the wall as intended. The last part of the video just shows that the animation moves correctly in the animation player when the root motion track property is cleared.

Here is the code. _process_update and _phsysics_update are called by the character body’s process and physics_process functions respectively.

	func _process_update(delta: float) -> void:
		var root_pos := character.animation_player.get_root_motion_position()
		var current_rotation := character.animation_player.get_root_motion_rotation_accumulator().inverse() \
		* character.get_quaternion()
		root_velocity = current_rotation * root_pos / delta
		var root_rotation := character.animation_player.get_root_motion_rotation()
		character.set_quaternion(character.get_quaternion() * root_rotation)
		
		#character.position += character.animation_player.get_root_motion_position()


	func _phsysics_update(delta: float) -> void:
		#character.position += character.animation_player.get_root_motion_position()

		character.velocity = root_velocity
		character.velocity.y = root_velocity.z
		character.velocity.z = 0
		character.move_and_slide()

Not sure where I’m going wrong. This is my first time using root motion.

2

Is the root bone oriented correctly in Blender? (Z axis is backwards (or forward) and X is sideways? ) Even if your Y and Z axis is switched up, I don’t really understand why the character is moving sideways.. Normally while walkng are you rotating the whole character or just the Mannequin node?

edit:

Here is what my root motion code is, it’s basically the same as your, but if normally you only rotate the mannequin then you need to calculate with that node’s rotation like me, not the characternode’s rotation. (in my code ‘visuals’ is your ‘mannequin’ node)

func handle_root_motion_movement(delta: float) → void:
    var visuals_quaternion: Quaternion = visuals.get_quaternion()
    set_velocity((animation_tree.get_root_motion_rotation_accumulator().inverse() * visuals_quaternion) * animation_tree.get_root_motion_position() / delta)
    visuals.set_quaternion(visuals_quaternion * animation_tree.get_root_motion_rotation())
1 Like
3

I rotate the whole character body when moving and the blend file appears to oriented correct.

I’m still scratching my head on this, but since swapping my Y and Z velocity fixed the problem I probably won’t dig into it more until it bites me again.