Using AnimationCurve and Vector3.Lerp to animate an object in Unity.

Create cube and script

• Create a new Unity3D project
• Create a cube and reset its position
• Select the cube
• Click Add Component > Add Script and name it Mover

A script is now attached to your cube.

• Doubleclick `mover’

• Create a public AnimationCurve with name MoveCurve

Your class should look like this:

using UnityEngine;

public class Mover : MonoBehaviour
{
public AnimationCurve MoveCurve;

private void Start()
{
}

private void Update()
{
}
}

• Switch back to Unity and doubleclick the MoveCurve area

The Curve editor opens

• Click the EaseIn function:

• Switch to Visual Studio and update your script like this:

using UnityEngine;

public class Mover : MonoBehaviour
{
public AnimationCurve MoveCurve;

private Vector3 _target;
private Vector3 _startPoint;
private float _animationTimePosition;

private void Start()
{
UpdatePath();
}

private void Update()
{
if (_target != transform.position)
{
    _animationTimePosition += Time.deltaTime;
    transform.position = Vector3.Lerp(_startPoint, _target, MoveCurve.Evaluate(_animationTimePosition));
}
else
{
    UpdatePath();
    _animationTimePosition = 0;
}
}

private void UpdatePath()
{
_startPoint = transform.position;
_target = Random.insideUnitSphere;
}
}

The Update method checks if the cube is at the target position. If it is not, the position will be calculated by the Lerp function.

How does the Lerp function work?

The Lerp function takes a starting and target vector and a position between 0 and 1. The next graph shows a Vector2 Lerp function.

In the script above the Lerp position _animationTimePosition starts at zero and is updated on each frame. When the cube is at its target position _animationTimePosition is reset to zero and a random new target position is being calculated.