> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinemation.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Full Body IK Modifier: Multi-Effector Character IK

> Apply two-bone IK to both arms and both legs simultaneously with a single modifier, enabling unified weight control for the full character IK setup.

The **Full Body IK** modifier solves IK for all four limbs — both arms and both legs — in a single pass. It is functionally equivalent to using four separate [Two Bone IK](/cas/modifiers/two-bone-ik) modifiers, but consolidates them into one entry in the Procedural Animation Settings list. Because all limb chains share one modifier, you can control their combined influence through a single set of [Weight Overrides](/cas/modifiers/overview#weight-overrides).

## Properties

Each limb (left arm, right arm, left leg, right leg) exposes the same group of parameters:

<ParamField path="Tip" type="KRigElement">
  The terminal bone of the limb chain — the hand for arms, the foot for legs. This bone will be driven to the **Target** position and rotation.
</ParamField>

<ParamField path="Target" type="KRigElement">
  The IK target bone that defines where the **Tip** should reach. This is typically an IK proxy bone such as `IK hand_r` or `IK foot_l` that you drive procedurally upstream in the modifier stack.
</ParamField>

<ParamField path="Pole Target" type="KRigElement">
  The hint (pole) bone that controls the bend direction of the limb. Use the elbow bone or a dedicated elbow hint for arms, and the knee bone or knee hint for legs.
</ParamField>

<ParamField path="Weight" type="float" default="1">
  Per-limb IK influence, from `0` (no IK applied) to `1` (full IK). Use this to blend individual limbs in or out independently — for example, keeping arm IK active while disabling leg IK during a jump.
</ParamField>

<ParamField path="Pole Weight" type="float" default="1">
  Controls how strongly the **Pole Target** pulls the elbow or knee in its direction. Reduce this value if the hint bone is in an awkward position and produces unwanted limb orientation.
</ParamField>

## Compared to Two Bone IK

|                       | **Full Body IK**        | **Two Bone IK**                               |
| --------------------- | ----------------------- | --------------------------------------------- |
| Limbs handled         | All four at once        | One chain per modifier                        |
| Modifiers in stack    | 1                       | 4 (one per limb)                              |
| Weight Override scope | All four limbs together | Per-limb independently                        |
| Use case              | Tight, unified control  | When limbs need very different override logic |

<Tip>
  Use **Full Body IK** when you want one Weight Override to affect the whole body simultaneously — for example, blending all IK off during a ragdoll transition. Use individual **Two Bone IK** modifiers when each limb needs separate override chains.
</Tip>

## Use Cases

* **Full-body interaction poses** — reach for ledges, grab handles, or brace against walls with all four limbs reacting together.
* **Unified IK weight control** — drive a single override to smoothly enable or disable all limb IK at once, such as entering or exiting a vehicle.
* **Simplified modifier stacks** — keep the Procedural Animation Settings list shorter and easier to read when detailed per-limb customisation is not needed.

## Setup Guide

<Steps>
  <Step title="Create IK proxy bones">
    Add empty GameObjects beneath the character root to serve as IK target bones for each limb (for example, `IK hand_l`, `IK hand_r`, `IK foot_l`, `IK foot_r`). These are the bones you will assign to the **Target** fields.
  </Step>

  <Step title="Copy real poses to IK targets">
    Add **Copy Bone** modifiers before Full Body IK in the stack to initialise each IK target with the animated hand or foot pose. This caches the base animation, letting subsequent modifiers alter the target position while the original pose is preserved.
  </Step>

  <Step title="Add Full Body IK">
    Add the **Full Body IK** modifier after your Copy Bone entries. Assign each **Tip**, **Target**, and **Pole Target** bone for all four limbs.
  </Step>

  <Step title="Tune per-limb weights">
    Adjust the **Weight** and **Pole Weight** values per limb. Add Weight Overrides at the modifier level to drive the combined influence from gameplay logic such as a grounded flag or an interaction state.
  </Step>
</Steps>