SkeletonIK

SkeletonIK

Inherits: Node < Object

SkeletonIK is used to place the end bone of a Skeleton bone chain at a certain point in 3D by rotating all bones in the chain accordingly.

Description

SkeletonIK is used to place the end bone of a Skeleton bone chain at a certain point in 3D by rotating all bones in the chain accordingly. A typical scenario for IK in games is to place a characters feet on the ground or a characters hands on a currently hold object. SkeletonIK uses FabrikInverseKinematic internally to solve the bone chain and applies the results to the Skeleton bones_global_pose_override property for all affected bones in the chain. If fully applied this overwrites any bone transform from Animations or bone custom poses set by users. The applied amount can be controlled with the interpolation property.

# Apply IK effect automatically on every new frame (not the current)
skeleton_ik_node.start()
# Apply IK effect only on the current frame
skeleton_ik_node.start(true)
# Stop IK effect and reset bones_global_pose_override on Skeleton
skeleton_ik_node.stop()
# Apply full IK effect
skeleton_ik_node.set_interpolation(1.0)
# Apply half IK effect
skeleton_ik_node.set_interpolation(0.5)
# Apply zero IK effect (a value at or below 0.01 also removes bones_global_pose_override on Skeleton)
skeleton_ik_node.set_interpolation(0.0)

Tutorials

https://godotengine.org/asset-library/asset/523

Properties

float	interpolation	`1.0`
Vector3	magnet	`Vector3( 0, 0, 0 )`
int	max_iterations	`10`
float	min_distance	`0.01`
bool	override_tip_basis	`true`
String	root_bone	`“”`
Transform	target	`Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0 )`
NodePath	target_node	`NodePath(“”)`
String	tip_bone	`“”`
bool	use_magnet	`false`

Methods

Skeleton	get_parent_skeleton ( ) const
bool	is_running ( )
void	start ( bool one_time=false )
void	stop ( )

Property Descriptions

float interpolation

Default	`1.0`
Setter	set_interpolation(value)
Getter	get_interpolation()

Interpolation value for how much the IK results are applied to the current skeleton bone chain. A value of 1.0 will overwrite all skeleton bone transforms completely while a value of 0.0 will visually disable the SkeletonIK. A value at or below 0.01 also calls Skeleton.clear_bones_global_pose_override.

Vector3 magnet

Default	`Vector3( 0, 0, 0 )`
Setter	set_magnet_position(value)
Getter	get_magnet_position()

Secondary target position (first is target property or target_node) for the IK chain. Use magnet position (pole target) to control the bending of the IK chain. Only works if the bone chain has more than 2 bones. The middle chain bone position will be linearly interpolated with the magnet position.

int max_iterations

Default	`10`
Setter	set_max_iterations(value)
Getter	get_max_iterations()

Number of iteration loops used by the IK solver to produce more accurate (and elegant) bone chain results.

float min_distance

Default	`0.01`
Setter	set_min_distance(value)
Getter	get_min_distance()

The minimum distance between bone and goal target. If the distance is below this value, the IK solver stops further iterations.

bool override_tip_basis

Default	`true`
Setter	set_override_tip_basis(value)
Getter	is_override_tip_basis()

If true overwrites the rotation of the tip bone with the rotation of the target (or target_node if defined).

String root_bone

Default	`“”`
Setter	set_root_bone(value)
Getter	get_root_bone()

The name of the current root bone, the first bone in the IK chain.

Transform target

Default	`Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0 )`
Setter	set_target_transform(value)
Getter	get_target_transform()

First target of the IK chain where the tip bone is placed and, if override_tip_basis is true, how the tip bone is rotated. If a target_node path is available the nodes transform is used instead and this property is ignored.

NodePath target_node

Default	`NodePath(“”)`
Setter	set_target_node(value)
Getter	get_target_node()

Target node NodePath for the IK chain. If available, the node’s current Transform is used instead of the target property.

String tip_bone

Default	`“”`
Setter	set_tip_bone(value)
Getter	get_tip_bone()

The name of the current tip bone, the last bone in the IK chain placed at the target transform (or target_node if defined).

bool use_magnet

Default	`false`
Setter	set_use_magnet(value)
Getter	is_using_magnet()

If true, instructs the IK solver to consider the secondary magnet target (pole target) when calculating the bone chain. Use the magnet position (pole target) to control the bending of the IK chain.

Method Descriptions

Skeleton get_parent_skeleton ( ) const

Returns the parent Skeleton Node that was present when SkeletonIK entered the SceneTree. Returns null if the parent node was not a Skeleton Node when SkeletonIK entered the SceneTree.

bool is_running ( )

Returns true if SkeletonIK is applying IK effects on continues frames to the Skeleton bones. Returns false if SkeletonIK is stopped or start was used with the one_time parameter set to true.

void start ( bool one_time=false )

Starts applying IK effects on each frame to the Skeleton bones but will only take effect starting on the next frame. If one_time is true, this will take effect immediately but also reset on the next frame.

void stop ( )

Stops applying IK effects on each frame to the Skeleton bones and also calls Skeleton.clear_bones_global_pose_override to remove existing overrides on all bones.