Vector3.Lerp

Parameters

Returns

Vector3 Interpolated value, equals to a + (b - a) * t.

Description

Linearly interpolates between two points.

Interpolates between the points a and b by the interpolant t. The parameter t is clamped to the range [0, 1]. This is most commonly used to find a point some fraction of the way along a line between two endpoints (e.g. to move an object gradually between those points).

The value returned equals a + (b - a) * t (which can also be written a * (1-t) + b*t).
When t = 0, Vector3.Lerp(a, b, t) returns a.
When t = 1, Vector3.Lerp(a, b, t) returns b.
When t = 0.5, Vector3.Lerp(a, b, t) returns the point midway between a and b.

// A short example of Vector3.Lerp usage.
// Add it to an object in your scene, and at Play time it will draw in the Scene View a small yellow line between the scene origin, and a position interpolated between two other positions (one on the up axis, one on the forward axis).

using UnityEngine;

public class ExampleClass : MonoBehaviour
{
    public int interpolationFramesCount = 45; // Number of frames to completely interpolate between the 2 positions
    int elapsedFrames = 0;

    void Update()
    {
        float interpolationRatio = (float)elapsedFrames / interpolationFramesCount;

        Vector3 interpolatedPosition = Vector3.Lerp(Vector3.up, Vector3.forward, interpolationRatio);

        elapsedFrames = (elapsedFrames + 1) % (interpolationFramesCount + 1);  // reset elapsedFrames to zero after it reached (interpolationFramesCount + 1)

        Debug.DrawLine(Vector3.zero, Vector3.up, Color.green);
        Debug.DrawLine(Vector3.zero, Vector3.forward, Color.blue);
        Debug.DrawLine(Vector3.zero, interpolatedPosition, Color.yellow);
    }
}

// A longer example of Vector3.Lerp usage.
// Drop this script under an object in your scene, and specify 2 other objects in the "startMarker"/"endMarker" variables in the script inspector window.
// At play time, the script will move the object along a path between the position of those two markers.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    // Transforms to act as start and end markers for the journey.
    public Transform startMarker;
    public Transform endMarker;

    // Movement speed in units per second.
    public float speed = 1.0F;

    // Time when the movement started.
    private float startTime;

    // Total distance between the markers.
    private float journeyLength;

    void Start()
    {
        // Keep a note of the time the movement started.
        startTime = Time.time;

        // Calculate the journey length.
        journeyLength = Vector3.Distance(startMarker.position, endMarker.position);
    }

    // Move to the target end position.
    void Update()
    {
        // Distance moved equals elapsed time times speed..
        float distCovered = (Time.time - startTime) * speed;

        // Fraction of journey completed equals current distance divided by total distance.
        float fractionOfJourney = distCovered / journeyLength;

        // Set our position as a fraction of the distance between the markers.
        transform.position = Vector3.Lerp(startMarker.position, endMarker.position, fractionOfJourney);
    }
}

Additional resources: Slerp, LerpUnclamped.