a | Start value, returned when t = 0. |
b | End value, returned when t = 1. |
t | Value used to interpolate between a and b. |
Vector3 Interpolated value, equals to a + (b - a) * t.
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.