IKControl

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IKControl instances generate procedural animation poses using Inverse Kinematics (IK). They allow you to make characters respond realistically to their environment.

For example, you can make a character place its hand on a door handle exactly, and the character will do so independently of its position. IKControls provide the advantage of needing to create much fewer animations for your game while giving your experience a more realistic and polished feel.

IKControls must be a child of a Humanoid or AnimationController with an Animator and have all of their required properties set properly, otherwise they don't have any effect. The required properties are Type, EndEffector, Target, ChainRoot. As soon as those are set, the IkControl modifies the pose of your character as you specify. The following code sample demonstrates how to set up your first IKControl and get started with creating more realistic animations for your game.

You can use IKControls to make a character:

  • Rotate its head and torso to look at a point of interest in the world.
  • Modify its feet positions to respond to dynamic terrain. Adjust its legs and feet to place them accordingly on terrain with rocks and slopes.
  • Hold a gun and place its hands appropriately on the grip without needing to create animations for each gun in the game.
  • Aim at a point in the world, so that the tip of the gun point exactly at what you want to shoot. Especially useful in third person shooters.
  • Place its hands on the steering wheel of a car and follow it when it rotates.
  • Much more!

IKControl will override the animation for all the parts between the ChainRoot and the EndEffector. You can enable/disable it using Enabled or change how much they have an effect over the underlying animation using the Weight. Be careful: if you do not set up your IKControls correctly, you might generate bad and unrealistic poses!

Code Samples

IKControl setup

1-- Place this script as a child of your character
2local character = script.Parent -- the character you want to modify.
3local ik = Instance.new("IKControl")
4ik.Parent = character:FindFirstChildOfClass("Humanoid")
5-- or "AnimationController" if your character has that
6ik.Type = Enum.IKControlType.Position
7ik.EndEffector = character:FindFirstChild("LeftHand", true)
8ik.ChainRoot = character:FindFirstChild("LeftUpperArm", true)
9ik.Target = workspace.target -- an Attachment or BasePart you created
10ik.Pole = nil -- optional part to indicate the bend of the elbow

Summary

Properties

The last part that you are interested in moving your character. For example, the upper arm. Must be an ancestor of EndEffector and be a BasePart or a Bone in your character.

Toggles the control on and off. True by default.

The part that you are interested in moving to reach the Target. For example, the hand of your character. Must be a descendant of ChainRoot and be a BasePart or a Bone in your character.

An additional offset applied on top of the Target to change where the EndEffector moves.

An optional instance that determines which way the chain bends. You can use this to specify which way an elbow or knee bends.

Specifies the order in which controls are solved. Higher values have higher priority.

The object that the EndEffector reaches for or points at. It can be anything that has a position in the world, such as BasePart, Attachment, Bone, or Motor6D.

Specifies how the solver satisfies this control.

Specifies how much this IK control should affect the final pose. Should be in the [0, 1] range.

Events

Methods

Properties

AlignmentOffset

ChainRoot

By specifying a ChainRoot and an EndEffector, you instruct the IKControl that it's allowed to move and rotate all parts between the two to move the EndEffector to the Target. For example, if you specify the LeftHand as EndEffector and LeftUpperArm as the ChainRoot, the control moves 3 parts: the LeftHand, the LeftLowerArm, and the LeftUpperArm. Avoid setting ChainRoot as the actual root of the character because that produces unrealistic results.

Enabled

This property allows you to toggle the IK control on and off. It's on by default. When Enabled is false, the IK control is off and isn't resolved by the underlying solver.

EndEffector

The EndEffector describes the last part in the chain of your character that you want to affect. For example, it could be the hand when you want to move the whole arm to reach a point. It must be a BasePart on a character, that has a Motor6D as its child, or a Bone

Offset

The offset is an additional CFrame applied on top of the Target's CFrame that produces the final CFrame used to place the EndEffector. It's identity by default, so if you don't set it, it has no effect and the EndEffector will use the Target's CFrame directly. You can animate it to create procedural animations such as typing on a keyboard. It's useful when the Target and EndEffector aren't aligned and you need to fix it with an additional rotation or translation.

The Pole is an optional Instance that gives you control over how intermediate parts in your character should bend. It can be anything that has a position in the world, such as BasePart, Attachment, Bone, Motor6D. It is by default nil. When you specify it, the underlying solver will make the parts bend towards it. When it is nil, the solver will try to make elbows and knees bend appropriately based on the limb of the character. The limb will be "Arm" when you select as EndEffector either the LeftHand or RightHand and as ChainRoot the corresponding LeftUpperArm or RightUpperArm, and it will be "Leg" when you select as EndEffector either the LeftFoot or RightFoot and as ChainRoot the corresponding LeftUpperLeg or RightUpperLeg. In all other cases, if you don't specify a pole, the chain might not bend as you expect.

Priority

When multiple controls are active on a character, the order in which they are solved by the underlying system affects the final generated pose. By changing this value, you specify the ordering in which controls are satisfied. Higher values have higher priority, and higher-priority controls are resolved later because their result might override the previous result of other controls. If you have multiple IK controls on a character and one is more important than the other, specify a lower priority for it. It is 0 by default, meaning all controls have the same priority.

Target

The Target represents a point (CFrame) in the world that you want your EndEffector to reach. The exact behavior of reaching can be set via the Type property, and an additional Offset can be applied on top of it to modify it. If you set a Target that will be moved either by physics or a script, at each frame the IKControl will try to satisfy it, automatically updating the point to reach.

By changing the Type, you can change the behavior of the control. These are the available options:

  • Transform: it's a full 6-DoF constraint. Aligns the EndEffector CFrame to that of the Target.
  • Position: aligns the EndEffector position to that of the Target.
  • Rotation: aligns the EndEffector rotation to that of the Target.
  • LookAt: moves and orients the whole chain to make an axis (by default the forward axis) on the EndEffector point at a position in the world specified by Target.

Weight

You can control how much a given control affects the character pose by using this property. Values should be in the [0, 1] range. 0 means no effect, and 1 means full effect of the IK control. Values outside this range are truncated. Smoothly varying this value allows you to blend in or out a specific control to avoid jarring motion. It is 1 by default.

Events

Methods