AUMSS/Runtime/BoneLookAtPlayer.cs

using UdonSharp;
using UnityEngine;
using VRC.SDKBase;

[UdonBehaviourSyncMode(BehaviourSyncMode.NoVariableSync)]
[DisallowMultipleComponent]
[AddComponentMenu("Artyom Scripting System/Bone Look At Player")]
public class BoneLookAtPlayer : UdonSharpBehaviour
{
    public GameObject objectToRotate; // The object to rotate
    public float rotationSpeed = 90.0f; // Maximum rotation speed in degrees per second
    public Vector3 rotationOffset; // Rotation offset for each axis

    private Transform objectTransform;
    private VRCPlayerApi[] players = new VRCPlayerApi[0]; // Reused every frame, grown when more players join

    void Start()
    {
        if (objectToRotate == null)
        {
            Debug.LogError("[AUMSS] Bone Look At Player: Object To Rotate isn't assigned, so nothing will turn.");
            enabled = false; // Stops Update, which would otherwise throw and halt the script
            return;
        }
        objectTransform = objectToRotate.transform;
    }

    void Update()
    {
        if (objectTransform == null) return; // Not set up (enabled = false only takes effect next frame)
        VRCPlayerApi nearestPlayer = GetNearestPlayer();
        if (nearestPlayer == null) return;

        Vector3 playerHeadPosition = nearestPlayer.GetTrackingData(VRCPlayerApi.TrackingDataType.Head).position;

        // Calculate the direction to look
        Vector3 directionToLook = playerHeadPosition - objectTransform.position;
        if (directionToLook != Vector3.zero)
        {
            Quaternion targetRotation = Quaternion.LookRotation(directionToLook);

            // Apply the rotation offset
            targetRotation *= Quaternion.Euler(rotationOffset);

            objectTransform.rotation = Quaternion.RotateTowards(objectTransform.rotation, targetRotation, rotationSpeed * Time.deltaTime);
        }
    }

    VRCPlayerApi GetNearestPlayer()
    {
        int count = VRCPlayerApi.GetPlayerCount();
        if (players.Length < count) players = new VRCPlayerApi[count];
        VRCPlayerApi.GetPlayers(players);

        VRCPlayerApi nearestPlayer = null;
        float closestDistance = float.MaxValue;
        Vector3 currentPosition = transform.position;

        for (int i = 0; i < count; i++)
        {
            VRCPlayerApi player = players[i];
            if (!Utilities.IsValid(player)) continue; // The local player counts too

            float distance = Vector3.Distance(currentPosition, player.GetPosition());
            if (distance < closestDistance)
            {
                closestDistance = distance;
                nearestPlayer = player;
            }
        }

        return nearestPlayer;
    }
}