Table of Contents

Class SkeletonModification2DFabrik

Namespace
Godot
Assembly
GodotSharp.dll

This SkeletonModification2D uses an algorithm called Forward And Backward Reaching Inverse Kinematics, or FABRIK, to rotate a bone chain so that it reaches a target.

FABRIK works by knowing the positions and lengths of a series of bones, typically called a "bone chain". It first starts by running a forward pass, which places the final bone at the target's position. Then all other bones are moved towards the tip bone, so they stay at the defined bone length away. Then a backwards pass is performed, where the root/first bone in the FABRIK chain is placed back at the origin. Then all other bones are moved so they stay at the defined bone length away. This positions the bone chain so that it reaches the target when possible, but all of the bones stay the correct length away from each other.

Because of how FABRIK works, it often gives more natural results than those seen in SkeletonModification2DCcdik. FABRIK also supports angle constraints, which are fully taken into account when solving.

Note: The FABRIK modifier has fabrik_joints, which are the data objects that hold the data for each joint in the FABRIK chain. This is different from Bone2D nodes! FABRIK joints hold the data needed for each Bone2D in the bone chain used by FABRIK.

To help control how the FABRIK joints move, a magnet vector can be passed, which can nudge the bones in a certain direction prior to solving, giving a level of control over the final result.

[GodotClassName("SkeletonModification2DFABRIK")]
public class SkeletonModification2DFabrik : SkeletonModification2D, IDisposable
Inheritance
SkeletonModification2DFabrik
Implements
Inherited Members

Constructors

SkeletonModification2DFabrik() 

public SkeletonModification2DFabrik()

Properties

FabrikDataChainLength

The number of FABRIK joints in the FABRIK modification.

public int FabrikDataChainLength { get; set; }

Property Value

int

TargetNodePath

The NodePath to the node that is the target for the FABRIK modification. This node is what the FABRIK chain will attempt to rotate the bone chain to.

public NodePath TargetNodePath { get; set; }

Property Value

NodePath

Methods

GetFabrikJointBone2DNode(int)

Returns the Bone2D node assigned to the FABRIK joint at jointIdx.

public NodePath GetFabrikJointBone2DNode(int jointIdx)

Parameters

jointIdx int

Returns

NodePath

GetFabrikJointBoneIndex(int)

Returns the index of the Bone2D node assigned to the FABRIK joint at jointIdx.

public int GetFabrikJointBoneIndex(int jointIdx)

Parameters

jointIdx int

Returns

int

GetFabrikJointMagnetPosition(int)

Returns the magnet position vector for the joint at jointIdx.

public Vector2 GetFabrikJointMagnetPosition(int jointIdx)

Parameters

jointIdx int

Returns

Vector2

GetFabrikJointUseTargetRotation(int)

Returns whether the joint is using the target's rotation rather than allowing FABRIK to rotate the joint. This option only applies to the tip/final joint in the chain.

public bool GetFabrikJointUseTargetRotation(int jointIdx)

Parameters

jointIdx int

Returns

bool

HasGodotClassMethod(in godot_string_name)

Check if the type contains a method with the given name. This method is used by Godot to check if a method exists before invoking it. Do not call or override this method.

protected override bool HasGodotClassMethod(in godot_string_name method)

Parameters

method godot_string_name

Name of the method to check for.

Returns

bool

HasGodotClassSignal(in godot_string_name)

Check if the type contains a signal with the given name. This method is used by Godot to check if a signal exists before raising it. Do not call or override this method.

protected override bool HasGodotClassSignal(in godot_string_name signal)

Parameters

signal godot_string_name

Name of the signal to check for.

Returns

bool

InvokeGodotClassMethod(in godot_string_name, NativeVariantPtrArgs, out godot_variant)

Invokes the method with the given name, using the given arguments. This method is used by Godot to invoke methods from the engine side. Do not call or override this method.

protected override bool InvokeGodotClassMethod(in godot_string_name method, NativeVariantPtrArgs args, out godot_variant ret)

Parameters

method godot_string_name

Name of the method to invoke.

args NativeVariantPtrArgs

Arguments to use with the invoked method.

ret godot_variant

Value returned by the invoked method.

Returns

bool

SetFabrikJointBone2DNode(int, NodePath)

Sets the Bone2D node assigned to the FABRIK joint at jointIdx.

public void SetFabrikJointBone2DNode(int jointIdx, NodePath bone2DNodePath)

Parameters

jointIdx int
bone2DNodePath NodePath

SetFabrikJointBoneIndex(int, int)

Sets the bone index, boneIdx, of the FABRIK joint at jointIdx. When possible, this will also update the bone2d_node of the FABRIK joint based on data provided by the linked skeleton.

public void SetFabrikJointBoneIndex(int jointIdx, int boneIdx)

Parameters

jointIdx int
boneIdx int

SetFabrikJointMagnetPosition(int, Vector2)

Sets the magnet position vector for the joint at jointIdx.

public void SetFabrikJointMagnetPosition(int jointIdx, Vector2 magnetPosition)

Parameters

jointIdx int
magnetPosition Vector2

SetFabrikJointUseTargetRotation(int, bool)

Sets whether the joint at jointIdx will use the target node's rotation rather than letting FABRIK rotate the node.

Note: This option only works for the tip/final joint in the chain. For all other nodes, this option will be ignored.

public void SetFabrikJointUseTargetRotation(int jointIdx, bool useTargetRotation)

Parameters

jointIdx int
useTargetRotation bool
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