# Ep.22 — Elbow · Hip Corrective

https://youtu.be/IOwz7uW5QBQ?si=Kx6XZdfT1nO7-paI

![Forearm Mid Corrective gear mark](image.png)

## 1. Why this episode

**Forearm Mid Corrective** and **Hip** in Mode are improved. Overseas Feedback asked for **inner-elbow** Corrective as well.

Bending used to fix the outside only. Corrective now also comes **outward per angle**. Modules keep updating after purchase.

Bone · controller names: [B.1](/guide/biped-plus/ep19-skin-bones-reference?lang=en) · [B.2](/guide/biped-plus/ep20-controller-reference?lang=en)

---

## 2. Forearm Mid Corrective · gear · Blend

Turn on **Forearm Mid Corrective** in Mode. A **gear** mark appears on the Corrective control. The gear is **Option**.

Every Parameter has **Lock / Unlock**. Animators can touch it, so this is **rigging space**. **Unlock** to edit, **Lock** when done.

| Item | Meaning |
|------|---------|
| **Blend 0.5** | Follows **half** of the elbow bend |
| Elbow **90°** | Corrective rotates **45°** |
| Raise the value | Follow amount increases |

![Push start and end · Value 0 at 90](image_1.png)

## 3. Push system

On a flat pose, bending does not Push. It starts from a **set angle**.

| Setting | Result |
|---------|--------|
| **70** | Push from about **70°** |
| **90** | Value is **0**, so nothing happens |
| Start · end | Treat them as the range |

**Cur Angle** is the elbow bend **right now**. The result is **Weight**.

![PRS Offset · inner Scale](image_2.png)

## 4. Offset · Candy Wrap · Skin Bone · off_dis

Think of it as adding **Offset** to Position · Rotation · Scale. Attribute examples: `push_pos_*` · `push_rot` · `push_scale_*`.

In production, people often **nudge** the elbow a little to sell the shape.

| Side | Common tweak |
|------|----------------|
| **Inner** | Lower Scale to stop **Candy Wrap**. `0.2` · `0.2` is easy |
| **Outer** | A little **Push** |

Once Corrective is set, the **Skin bone follows**. Scale applies too. Compatibility with Unreal and other Game Engines is checked.

If the control seat feels wrong, move it with **off_dis**.

![Hip Blend follows half](image_3.png)

## 5. Hip · Lock · Key

Rotate the hip and it **Pushes** too. **Blend** follows half by default. Lower Blend to follow less.

You can also set **Controller Offset**. Attribute examples: `off_pos_*` · `blend`.

When the Value is right, **Lock** it.

| Rule | Why |
|------|-----|
| **Do not key** | This controller is not a keying seat |
| **Lock** | Animator values stay put even if numbers move |
| The Lock moment | That is the end of Setup |

Hip Corrective **Pushes at 90°** for both front and side. Hip has **no live Weight readout** yet. That comes later. If it Pushes too much, set Push to **0**.

You can drop side Scale to `0.5`, or customize rotation to `45°`. Front and back work the same way.

![Hip Auto · front Push](image_4.png)

## 6. Auto · front

Turn **Auto** on and Push also runs when the leg goes forward. A **90°** front rotate behaves the same. Park a value like `5`, then raise it in `0.5` steps.

Want **30°** on Z? Enter `30`.

Hip and elbow shapes are hard to hold. That is why **Corrective Rigging** matters.

---

## Notes

- **Do not key** these controllers. **Lock** when they are set.
- Touch Parameters only after **Unlock**. This is rigging space.
- A Push start of **90** yields Value 0, so nothing moves.
- Hip has no live Weight UI yet. Tune by eye.
- Knee Corrective is not this episode.

---

## Related

- Upper Arm shoulder: [Ep.22-1](/guide/biped-plus/ep22-1_upper-arm?lang=en)
- Create controllers: [Ep.4](/guide/biped-plus/ep04-controller?lang=en)
- Skin bones `Skin_*_ForeArm_Cor` · `Skin_*_*_Hip`: [B.1](/guide/biped-plus/ep19-skin-bones-reference?lang=en)
- Controllers `Ctrl_*_ForeArm_Cor` · `Ctrl_*_*_Hip`: [B.2](/guide/biped-plus/ep20-controller-reference?lang=en)

---

## One-line flow

```
Mode → Forearm Mid Corrective
  → Unlock
  → Blend (0.5 = half)
  → Push start angle (70 etc. · 90 = 0)
  → Check Cur Angle · Weight
  → Offset (pos / rot / scale)
  → Inner Scale ↓ (Candy Wrap) · outer Push
  → off_dis for control seat
  → Hip: Blend · Offset · front/side 90°
  → Auto (leg forward)
  → Lock · no keys
```