# Step Modifier

{% embed url="<https://drive.google.com/file/d/1D6u1CEKc6WwVZxQAqTQX3ALm9MeT2vP3/view?usp=sharing>" %}

## Overview

**Step Modifier** creates procedural steps to avoid feet sliding when changing animation states (e.g., standing to crouching).

<figure><img src="/files/KgsvoaI0De17YwBKie4E" alt="" width="440"><figcaption></figcaption></figure>

#### Bone References

> Here you will find bone references to assign.

* **Pelvis** is the character pelvis or hip bone.
* **Right** and **Left Foot IK Target**: is the IK bone for the right or left foot. It's usually set to IK foot\_r or IK foot\_l.

#### Ground Alignment

> Here you will find settings for snapping feet to the ground.

* **Right Foot** is the character right foot bone (not an IK).
* **Left Foot** is the character left foot bone (not an IK).
* **Leg Stretch Factor** fine-tunes how aggressively the system detects and corrects leg stretching. Higher values increase the likelihood that a leg will be classified as “stretched” and have its length adjusted accordingly.

#### Step Motion

> Here you will find animation curves for feet and pelvis.

* **Lead Foot Motion** is the position animation for the leading foot (the one making a step first).
* **Follow Foot Motion** is the position animation for the following foot (the one making a step after the leading one).
* **Pelvis Motion** is the position animation for pelvis.

{% hint style="info" %}
**Note**: The Animation Curve values must at end zero for all motions.
{% endhint %}

* **Lead**, **Follow Foot** and **Pelvis Scale** are values that will scale each motion per-axis. For example, the X component will scale the X axis.
* **Play Rate** is the speed multiplier for this step motion.

#### Stride Settings

> Here you will properties that define the procedural step.

* **Animated Lead Foot** defines the leading foot for this step. A leading foot is the one making a step first.
* **Force Lead Foot** controls if the step must always start with a leading foot. If disabled, the leading foot will be determined based on the velocity vector.
* **Max Allowed Strength** defines the max allowed step length. If exceeded, feet will be moved in the movement direction to avoid stretching.
* **Max Allowed Offset Angle** defines the max allowed character rotation to avoid leg twisting. If exceeded, feet will be rotated around pelvis to compensate the rotation.
* **Step Cooldown Rate** is the time in seconds needed to pass before making the next step.

## Use-cases

**Step Modifier** can be used for any situation to replace feet sliding with a nice procedural step. Here are most popular applications:

1. Movement stop or start transitions.
2. New stance transition (e.g., going from rifle to sword, or from standing to crouching).
3. Turning in place.

{% hint style="success" %}
**Tip**: CAS comes with example Step presets, these can be found in KINEMATION/CharacterAnimationSystem/Examples/Steps/.
{% endhint %}

### Recommended settings

To get best results, make sure that:

1. **MaxAllowedStride** is set to \~0.3-0.4 to avoid character legs being strecthed. Setting this to a too small number will result in abrupt, unnatural steps.
2. **MaxAllowedOffsetAngle** is set to \~45 degrees to avoid legs being twisted.
3. **StepCooldownRate** is set to \~0.3-0.4s to handle player input-spamming situations.
4. **Force Lead Foot** can be used for specific cases, like turning in place — we only want to turn right with the right foot, and vice versa.
5. All animation curves start at zero for a seamless transition.

These settings might differ from one character model to another, so it's fine to experiment and find what works best for your character.

### How to play steps

Steps can be played at runtime using by updating the animation modifier:

{% code title="YourComponent.cs" overflow="wrap" %}

```csharp
private ProceduralAnimationComponent _proceduralAnimation;
private StepModifierSettings _yourStepModifier;

private void YourMethod()
{
    _proceduralAnimation.UpdateAnimationModifier(_yourStepModifier);
}
```

{% endcode %}

It's possible to play steps when a transition is entering or exiting a state in the Animator:

<figure><img src="/files/B7L9AoQeICP3x1Z01lTz" alt=""><figcaption><p>Syncing steps with animation states.</p></figcaption></figure>

This feature is used in the CAS Demo to play steps when turning in place or finishing climbing.


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