VRChat Global Fog Controller（全然ちゃんと動作確認してないよ！）

FogController.cs

using UdonSharp;
using UnityEngine;
using UnityEngine.UI;
using VRC.SDKBase;
using VRC.Udon;

namespace Tsukemonoya
{
    [UdonBehaviourSyncMode(BehaviourSyncMode.Manual)]
    public class FogController : UdonSharpBehaviour
    {
        [SerializeField] Slider densitySlider;
        [SerializeField] Slider fogStartSlider;
        [SerializeField] Slider fogEndSlider;

        [UdonSynced, FieldChangeCallback(nameof(SyncedFog))]
        bool syncedFog;
        public bool SyncedFog
        {
            get => syncedFog;
            set
            {
                syncedFog = value;
                RenderSettings.fog = value;
            }
        }

        [SerializeField, UdonSynced, FieldChangeCallback(nameof(SyncedColor))]
        Color32 syncedColor;

        public Color32 SyncedColor
        {
            get => syncedColor;
            set
            {
                syncedColor = value;
                RenderSettings.fogColor = value;
            }
        }

        [UdonSynced, FieldChangeCallback(nameof(SyncedFogMode))]
        int syncedFogMode;
        public int SyncedFogMode
        {
            get => syncedFogMode;
            set
            {
                syncedFogMode = value;
                RenderSettings.fogMode = (FogMode)value;
            }
        }

        [UdonSynced, FieldChangeCallback(nameof(SyncedDensity))]
        float syncedDensity;
        public float SyncedDensity
        {
            get => syncedDensity;
            set
            {
                deserializing = true;
                if (!Networking.IsOwner(gameObject))
                {
                    densitySlider.value = value;
                }
                syncedDensity = value;
                RenderSettings.fogDensity = value;
                deserializing = false;
            }
        }

        [UdonSynced, FieldChangeCallback(nameof(SyncedFogStart))]
        float syncedFogStart;
        public float SyncedFogStart
        {
            get => syncedDensity;
            set
            {
                deserializing = true;
                if (!Networking.IsOwner(gameObject))
                {
                    fogStartSlider.value = value;
                }
                syncedFogStart = value;
                RenderSettings.fogStartDistance = value;
                deserializing = false;
            }
        }

        [UdonSynced, FieldChangeCallback(nameof(SyncedFogEnd))]
        float syncedFogEnd;
        public float SyncedFogEnd
        {
            get => syncedDensity;
            set
            {
                deserializing = true;
                if (!Networking.IsOwner(gameObject))
                {
                    fogEndSlider.value = value;
                }
                syncedFogEnd = value;
                RenderSettings.fogEndDistance = value;
                deserializing = false;
            }
        }
        bool deserializing;

        // call from densitySlider
        public void OnDensityChanged()
        {
            if (deserializing) return;
            Networking.SetOwner(Networking.LocalPlayer, gameObject);
            SyncedDensity = densitySlider.value;
            RequestSerialization();
        }

        // call from fogStartSlider
        public void OnFogStartChanged()
        {
            if (deserializing) return;
            Networking.SetOwner(Networking.LocalPlayer, gameObject);
            SyncedFogStart = fogStartSlider.value;
            RequestSerialization();
        }

        // call from fogEndSlider
        public void OnFogEndChanged()
        {
            if (deserializing) return;
            Networking.SetOwner(Networking.LocalPlayer, gameObject);
            SyncedFogEnd = fogEndSlider.value;
            RequestSerialization();
        }

        void Start()
        {
            if (Networking.IsOwner(gameObject))
            {
                if (densitySlider != null)
                {
                    SyncedDensity = densitySlider.value;
                }
                if (fogStartSlider != null)
                {
                    SyncedFogStart = fogStartSlider.value;
                }
                if (fogEndSlider != null)
                {
                    SyncedFogStart = fogEndSlider.value;
                }
                RequestSerialization();
            }
            RenderSettings.fogColor = SyncedColor;
        }

        public override void Interact()
        {
            ToggleFog();
        }

        // call from other scripts or UI
        public void SetFogColor(Color32 color)
        {
            Networking.SetOwner(Networking.LocalPlayer, gameObject);
            SyncedColor = color;
            RequestSerialization();
        }

        // call from other scripts or UI
        public void ToggleFog()
        {
            Networking.SetOwner(Networking.LocalPlayer, gameObject);
            SyncedFog = !SyncedFog;
            RequestSerialization();
        }

        // call from other scripts or UI
        public void ToggleFogMode()
        {
            switch (RenderSettings.fogMode)
            {
                case FogMode.Linear:
                    SyncedFogMode = (int)FogMode.Exponential;
                    break;
                case FogMode.Exponential:
                    SyncedFogMode = (int)FogMode.ExponentialSquared;
                    break;
                case FogMode.ExponentialSquared:
                    SyncedFogMode = (int)FogMode.Linear;
                    break;
            }
        }
    }
}

InteractTrigger.cs

using UdonSharp;
using UnityEngine;
using VRC.SDKBase;
using VRC.Udon;

namespace Tsukemonoya
{
    // A simple UdonSharp script to call target's method on Interact.
    [UdonBehaviourSyncMode(BehaviourSyncMode.NoVariableSync)]
    public class InteractTrigger : UdonSharpBehaviour
    {
        [SerializeField]
        UdonBehaviour target;
        [SerializeField]
        string eventName;

        public override void Interact()
        {
            target.SendCustomEvent(eventName);
        }
    }
}