Align the mesh (child object) with terrain normals?

Unity Engine
1

Hey,

I have read and tried many of the suggestions, but I am stuck with this for over 3 days. I have a parent game object that has a navmesh agent and a child object that contains the rig + skinned mesh. So I would like to rotate that child container with the terrain normal as the navmesh agent is moving, but nothing I’ve tried offers smooth rotation. I only want to rotate the character up and down as it’s climbing a hill or going downhills. So far I have this, which is rotating the child along X Y Z and it’s not smooth, really glitching as the character is moving fast (it’s a deer).

 public void Align()
        {
            RaycastHit hit;
            Vector3 theRay = transform.TransformDirection(Vector3.down);

            if (Physics.Raycast(new Vector3(transform.position.x, transform.position.y + 3, transform.position.z),
                theRay, out hit, 20, _terrainLayer))
            {
                Vector3 normal = hit.normal;


                transform.rotation = Quaternion.FromToRotation(transform.up, hit.normal) * transform.rotation;

            }
        }

I am following this tutorial to set up the navmesh agent and turning with root motion.

Any suggestions would be great, I am really stuck with this. At this point I am really wondering if that’s possible to do in Unity, I have read over 30 posts and tried lots of things and nothing seems to be smoothly lerping the rotation without making the npc go crazy while rotating.

2

You are doing it right, the only thing you would need to add is the smoothing between current rotation and target rotation (terrain normal).

private Quaternion targetRotation
public void Align()
        {
            RaycastHit hit;
            Vector3 theRay = transform.TransformDirection(Vector3.down);
            if (Physics.Raycast(new Vector3(transform.position.x, transform.position.y + 3, transform.position.z),
                theRay, out hit, 20, _terrainLayer))
            {
                Vector3 normal = hit.normal;
               targetRotation = Quaternion.FromToRotation(transform.up, hit.normal) * transform.rotation;
            }
        }

void Update(){
    transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, 0.1f/Time.deltaTime);

}

I’m not sure if 0.1f/deltaTime is the right way to do athe smoothing in 0.1 sec, it might be the other way around deltaTime/0.1f

2 Likes
3

have you tried calling this in LateUpdate?

also, total aside, like 4 is the same as “-transform.up”

4

Time.DeltaTime / 0.1f is giving a nice result, except the child’s forward rotation doesn’t follow the agent’s rotation (attached to it’s parent) so the deer looks to the left while moving forward. It’s something like this:

5

I modified some of the things and now it’s looking better. I am still experimenting where to call the Align method - Update, LateUpdate or FixedUpdate. It seems like FixedUpdate gives the best result, but I’m not sure, the difference is really minor and it’s hard to compare.

 private void Align()
        {
            RaycastHit hit;
            Vector3 theRay = -transform.up;


            if (Physics.Raycast(new Vector3(transform.position.x, transform.position.y + 3, transform.position.z),
                theRay, out hit, 20, _terrainLayer))
            {

                Quaternion  targetRotation = Quaternion.FromToRotation(transform.up, hit.normal) * transform.parent.rotation;

                transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, Time.deltaTime / 0.15f);
            }
        }
1 Like
6

That much i can’t help, maybe try replacing

   targetRotation = Quaternion.FromToRotation(transform.up, hit.normal) * transform.rotation;

with this

   targetRotation = Quaternion.Euler(hit.normal);

If that doesn’t work you can try proyecting the NM Agent’s forward against the plain with normal transform.up and make a look at

void Update(){

transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, 0.1f/Time.deltaTime);
Vector3 for = Vector3.ProyectOnPlane(transform.parent.forward,transform.up).normalized;
transform.LookAt(transform.position + for);

}
7

Hey @skinwalker_1 . I have used your code (exactly as it is here in your last comment) as I was struggling with the same problem. It works like a charm for me. I have tried in the Update() and in the FixedUpdate() too. There is no visible difference for me. My character has no animations yet. Just the mesh, speed is 2 for the navMesh agent and everything seems ok. Maybe your problem comes from the animator as the code seems to be doing exactly what it should. Thanks a lot! I was trying to make that bloody sheep walk properly for the past two days. Cheerio!!

2 Likes
8

Good to see it’s working for your project. I think my problem was because I didn’t properly order the hierarchy of that object and bones were rotated weirdly, now this problem is fixed and working well with the code I posted.

1 Like