SkeletonModification2DFABRIK
A modification that uses FABRIK to manipulate a series of Bone2D nodes to reach a target.
class SkeletonModification2DFABRIKThis 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.
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.
Superclasses
class SkeletonModification2DBase class for resources that operate on
Bone2Ds in aSkeleton2D.
Citizens in SwiftGodot
Conformances
protocol CustomStringConvertibleA type with a customized textual representation.
protocol EquatableA type that can be compared for value equality.
protocol HashableA type that can be hashed into a
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protocol VariantRepresentableTypes that conform to VariantRepresentable can be stored directly in
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Type members
Instance members
var fabrikDataChainLength: Int32The number of FABRIK joints in the FABRIK modification.
var targetNodepath: NodePathThe 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.
func getFabrikJointBone2dNode(jointIdx: Int32) -> NodePath Returns the
Bone2Dnode assigned to the FABRIK joint atjointIdx.func getFabrikJointBoneIndex(jointIdx: Int32) -> Int32 Returns the index of the
Bone2Dnode assigned to the FABRIK joint atjointIdx.func getFabrikJointMagnetPosition(jointIdx: Int32) -> Vector2 Returns the magnet position vector for the joint at
jointIdx.func getFabrikJointUseTargetRotation(jointIdx: Int32) -> Bool 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.
func setFabrikJointBone2dNode(jointIdx: Int32, bone2dNodepath: NodePath) Sets the
Bone2Dnode assigned to the FABRIK joint atjointIdx.func setFabrikJointBoneIndex(jointIdx: Int32, boneIdx: Int32) Sets the bone index,
boneIdx, of the FABRIK joint atjointIdx. When possible, this will also update thebone2d_nodeof the FABRIK joint based on data provided by the linked skeleton.func setFabrikJointMagnetPosition(jointIdx: Int32, magnetPosition: Vector2) Sets the magnet position vector for the joint at
jointIdx.func setFabrikJointUseTargetRotation(jointIdx: Int32, useTargetRotation: Bool) Sets whether the joint at
jointIdxwill use the target node’s rotation rather than letting FABRIK rotate the node.