Add SkyboxEnvironmentUpdater: runtime sky reflection + ambient

New [ExecuteAlways] component that renders the skybox (or an optional override material) into a custom reflection cubemap and refreshes DynamicGI so smooth/metallic materials reflect the sky without a baked LightingData asset. Uses a deferred apply plus a synchronous warm-render so the ambient probe resolves after domain reload; runs the reflection capture as a stripped CameraType.Reflection to avoid the URP MIP-bind error. Exposes reflection intensity (0..4) and optional ambient override.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/Components/SkyboxEnvironmentUpdater.cs

@@ -0,0 +1,164 @@
+using System.Collections;
+using UnityEngine;
+using UnityEngine.Rendering;
+using UnityEngine.Rendering.Universal;
+
+/// <summary>
+/// Builds the environment reflection from the current Skybox in memory (renders
+/// the sky into a cubemap and assigns it as the Custom reflection), so
+/// smooth/metallic materials reflect the sky WITHOUT a baked LightingData.asset.
+/// Runs in Edit and Play mode ([ExecuteAlways]); drop it on one object per scene
+/// (or a prefab that lives in every scene) and you never have to assign a foreign
+/// LightingData again — also works for runtime-loaded / procedural scenes.
+///
+/// Why a rendered cubemap and not <see cref="DynamicGI.UpdateEnvironment"/>:
+/// in this project UpdateEnvironment does NOT produce a valid skybox reflection
+/// probe (a mirror stays black), so <see cref="RenderSettings.reflectionIntensity"/>
+/// had nothing to scale. Rendering the sky into a Custom reflection cubemap gives a
+/// real reflection that intensity can actually drive.
+///
+/// The skybox AMBIENT probe still comes from UpdateEnvironment — but it only convolves a
+/// non-zero probe once the sky has actually been rendered this session. Straight after a
+/// domain reload / scene load / play-start the sky hasn't rendered yet, so the probe is
+/// ZERO and the Environment intensity multiplier has nothing to scale ("doesn't take
+/// effect" until a manual re-enable). Fix: do one synchronous full-screen sky render to
+/// "warm" the sky right before UpdateEnvironment — deterministic, no waiting on renders.
+/// (RenderToCubemap does NOT warm the ambient path; a normal Camera.Render does.)
+/// </summary>
+[ExecuteAlways]
+[DisallowMultipleComponent]
+public class SkyboxEnvironmentUpdater : MonoBehaviour
+{
+    [Range(0f, 4f)]
+    public float environmentLightingIntensity = 1;
+    
+    [Header("Reflections")]
+
+    [Tooltip("Resolution of the generated sky reflection cubemap (power of two).")]
+    public int reflectionResolution = 128;
+
+    [Tooltip("How strongly the sky reflection tints reflective/metallic surfaces. 1 = neutral; the Lighting window slider caps at 1, but higher values (via this field) over-drive the reflection for a glossier metal look. Only applied while Force Skybox Reflections is on.")]
+    [Range(0f, 4f)]
+    public float reflectionIntensity = 1f;
+    
+    [Tooltip("Optional: render THIS sky material into the reflection cubemap instead of the scene's global Skybox. Leave empty to use RenderSettings.skybox. Only affects the reflection — the visible scene skybox is unchanged.")]
+    public Material reflectionSkyOverride;
+
+    [System.NonSerialized] Cubemap _reflectionCube;
+
+    void OnDisable()
+    {
+#if UNITY_EDITOR
+        UnityEditor.EditorApplication.delayCall -= Apply;
+#endif
+        if (!_reflectionCube)
+            return;
+
+        if (RenderSettings.customReflectionTexture == _reflectionCube)
+            RenderSettings.customReflectionTexture = null;
+
+        DestroyImmediate(_reflectionCube);
+
+        _reflectionCube = null;
+    }
+
+    void OnValidate()
+    {
+        if (this && isActiveAndEnabled)
+            OnEnable();
+        else
+            OnDisable();
+    }
+
+    void OnEnable()
+    {
+        if (!RenderSettings.skybox && !reflectionSkyOverride)
+            return;
+
+#if UNITY_EDITOR
+        if (!Application.isPlaying)
+        {
+            UnityEditor.EditorApplication.delayCall -= Apply;
+            UnityEditor.EditorApplication.delayCall += Apply;
+            return;
+        }
+#endif
+        StartCoroutine(ApplyNextFrame());
+    }
+
+    IEnumerator ApplyNextFrame()
+    {
+        yield return null;
+        Apply();
+    }
+
+    void Apply()
+    {
+        if (!this || !isActiveAndEnabled)
+            return;
+
+        if (!RenderSettings.skybox && !reflectionSkyOverride)
+            return;
+
+        RenderSettings.ambientIntensity = environmentLightingIntensity;
+
+        var camGo = new GameObject("__SkyboxEnvCam") { hideFlags = HideFlags.HideAndDontSave };
+        try
+        {
+            var cam = camGo.AddComponent<Camera>();
+            cam.enabled = false;
+            cam.cullingMask = 0;
+            cam.clearFlags = CameraClearFlags.Skybox;
+            cam.cameraType = CameraType.Reflection;
+
+            var camData = camGo.AddComponent<UniversalAdditionalCameraData>();
+            camData.renderPostProcessing = false;
+            camData.requiresDepthTexture = false;
+            camData.requiresColorTexture = false;
+            camData.renderShadows = false;
+
+            if (reflectionSkyOverride)
+                camGo.AddComponent<Skybox>().material = reflectionSkyOverride;
+
+            camGo.transform.position = transform.position;
+
+            var rt = RenderTexture.GetTemporary(64, 64, 16);
+            cam.targetTexture = rt;
+            cam.Render();
+            cam.targetTexture = null;
+            RenderTexture.ReleaseTemporary(rt);
+
+            EnsureReflectionCubemap();
+            cam.RenderToCubemap(_reflectionCube);
+        }
+        finally
+        {
+            DestroyImmediate(camGo);
+        }
+
+        RenderSettings.defaultReflectionMode = DefaultReflectionMode.Custom;
+        RenderSettings.customReflectionTexture = _reflectionCube;
+        RenderSettings.reflectionIntensity = reflectionIntensity;
+
+        RenderSettings.ambientMode = AmbientMode.Skybox;
+        DynamicGI.UpdateEnvironment();
+    }
+
+    void EnsureReflectionCubemap()
+    {
+        int size = Mathf.Max(16, reflectionResolution);
+
+        if (!_reflectionCube || _reflectionCube.width != size)
+        {
+            if (_reflectionCube)
+            {
+                DestroyImmediate(_reflectionCube);
+            }
+
+            _reflectionCube = new Cubemap(size, TextureFormat.RGBA32, true)
+            {
+                name = "SkyboxReflection (generated)"
+            };
+        }
+    }
+}

Assets/Scripts/Components/SkyboxEnvironmentUpdater.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 8ad6962cd13b2914a82ab60384f37a3b