# Custom Curve

Here's a sample implementation of a [Sawtooth wave](https://en.wikipedia.org/wiki/Sawtooth_wave).

## Curve Definition

{% code fullWidth="true" %}

```cs
using System;
using FXEngine.ShakeFX;
using FXEngine.ShakeFX.Curves;
using UnityEngine;

// Sawtooth wave https://en.wikipedia.org/wiki/Sawtooth_wave
[Serializable]
public class SawtoothCurve : Curve
{
    private class RuntimeCurve : IRuntimeCurve
    {
        public float Frequency;
        public float Offset;

        public float Evaluate(in RuntimeCurveEvaluationContext context)
        {
            // Apply Frequency
            var x = context.ElapsedTime * Frequency + Offset;

            var fractional = x - Mathf.Floor(x);
            return fractional;
        }
    }

    // The oscillation frequency in cycles per second (Hz).
    public float Frequency = 3f;

    public override IRuntimeCurve CreateRuntimeCurve(in RuntimeCurveCreationContext context)
    {
        return new RuntimeCurve()
        {
            Frequency = Frequency,
            Offset = context.Offset,
        };
    }
}
```

{% endcode %}

## Motion Definitions

To use this curve inside a shake asset you'll need to define the motions:

```cs
using FXEngine.ShakeFX.Motions.Core;

// Single-axis position (Vector3) motion using a sawtooth wave.
[Motion("1 Axis/Sawtooth")]
[Serializable]
public class SawtoothMotion1AxisPosition : Motion1AxisPosition<SawtoothCurve>
{
    
}

// Single-axis rotation (Quaternion) motion using a sawtooth wave.
[Motion("1 Axis/Sawtooth")]
[Serializable]
public class SawtoothMotion1AxisRotation : Motion1AxisRotation<SawtoothCurve>
{
    
}

// Uniform (Vector3) motion using a sawtooth wave.
[Motion("Uniform/Sawtooth")]
[Serializable]
public class SawtoothMotionUniform : MotionUniform<SawtoothCurve>
{
    
}

// 1D (float) motion using a sawtooth wave.
[Motion("Sawtooth")]
[Serializable]
public class SawtoothMotion1D : Motion1D<SawtoothCurve>
{
    
}
```

## Result

The sawtooth motions are assignable to properties inside shake assets:

<figure><img src="/files/xsvXG1TrE3UXCWioN05O" alt="" width="375"><figcaption></figcaption></figure>


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