Camera Smooth Follow 2D from UnityScript to C# using Unity3D

Question

I am making a script to be used on the Main Camera object of Unity3D so the camera follows the character in a 2D platformer world.

I tried to translate this from a UnityScript script to c#, I am getting an error in line 26: "Cannot modify a value type return value of 'UnityEngine.Transform.position'. Consider storing the value in a temporary variable."

Original UnityScript Version

var cameraTarget : GameObject; var player : GameObject; var smoothTime : float = 0,1; var cameraFollowX : boolean = true; var cameraFollowY : boolean = true; var cameraFollowHeight : boolean = false; var cameraHeight : float = 2.5; var velocity : Vector2; private var thisTransform : Transform; function Start () { thisTransform = transform; } function Update () { if (cameraFollowX) { thisTransform.position.x = Mathf.SmoothDamp (thisTransform.position.x, cameraTarget.transform.position.x, velocity.x, smoothTime); } if (cameraFollowY) { thisTransform.position.y = Mathf.SmoothDamp (thisTransform.position.y, cameraTarget.transform.position.y, velocity.y, smoothTime); } if (!cameraFollowX & cameraFollowHeight) { camera.transform.position.y = cameraHeight; } }

My C# Version

using UnityEngine; using System.Collections; public class CameraSmoothFollow : MonoBehaviour { public GameObject cameraTarget; // object to look at or follow public GameObject player; // player object for moving public float smoothTime = 0.1f; // time for dampen public bool cameraFollowX = true; // camera follows on horizontal public bool cameraFollowY = true; // camera follows on vertical public bool cameraFollowHeight = true; // camera follow CameraTarget object height public float cameraHeight = 2.5f; // height of camera adjustable public Vector2 velocity; // speed of camera movement private Transform thisTransform; // camera Transform // Use this for initialization void Start () { thisTransform = transform; } // Update is called once per frame void Update () { if (cameraFollowX){ thisTransform.position.x = Mathf.SmoothDamp (thisTransform.position.x, cameraTarget.transform.position.x, ref velocity.x, smoothTime); // Here i get the error } if (cameraFollowY) { // to do } if (!cameraFollowX & cameraFollowHeight) { // to do } } }

Any help will be appreciated.

CC Inc · Accepted Answer · 2013-08-28 00:26:40Z

This error occurs because Transform.position is of a value type (probably a struct). This means that when you access the X property of position, you are accessing a COPY and NOT the real thing. To assign to the position property, you will need to create a new Vector3 and assign it to the position property. Your code will look something like this:

thisTransform.position = new Vector3 (Mathf.SmoothDamp (thisTransform.position.x, cameraTarget.transform.position.x, ref velocity.x, smoothTime), thisTransform.position.y, thisTransform.position.z);

or perhaps more cleaner:

float tempX = new Vector3 (Mathf.SmoothDamp (thisTransform.position.x, cameraTarget.transform.position.x, ref velocity.x, smoothTime); thisTransform.position = new Vector3 (tempX, thisTransform.position.y, thisTransform.position.z);

craig lerr · Accepted Answer · 2015-02-21 22:17:12Z

You can also use this smooth follow script for both 2d and 3d camera and its very simple.

using UnityEngine; using System.Collections; public class FollowCamera : MonoBehaviour { public float interpVelocity; public float minDistance; public float followDistance; public GameObject target; public Vector3 offset; Vector3 targetPos; // Use this for initialization void Start () { targetPos = transform.position; } // Update is called once per frame void FixedUpdate () { if (target) { Vector3 posNoZ = transform.position; posNoZ.z = target.transform.position.z; Vector3 targetDirection = (target.transform.position - posNoZ); interpVelocity = targetDirection.magnitude * 5f; targetPos = transform.position + (targetDirection.normalized * interpVelocity * Time.deltaTime); transform.position = Vector3.Lerp( transform.position, targetPos + offset, 0.25f); } } }

got it from github here https://gist.github.com/unity3diy/5aa0b098cb06b3ccbe47

It will be more fun if it works with my 3d camera too. let me check it .. by the way thanks :)
This is incorrect, FixedUpdate is for physics, you should have player movement updates in Update() and not FixedUpdate()

Irshad · Accepted Answer · 2016-03-11 10:51:29Z

1

Use FixedUpdate()

If it's Update() the camera jerking will occur.

edited Mar 11, 2016 at 10:51

Irshad

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answered Mar 11, 2016 at 10:46

Alan Wang

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