Revert "feat(sky): the night sky wheels with the Dereth clock; uniform time fade with a scoped twilight band"

This reverts commit 0dac024cdb.

src/AcDream.App/Composition/FrameRootComposition.cs

@@ -333,18 +333,6 @@ internal sealed class FrameRootCompositionPhase
                 skyForNightSky.EnhancedNightSkyActive = () =>
                     nightSkyController.ActiveRuntime?.Descriptor.Id
                         == AcDream.App.Rendering.Packs.BuiltInAtmosphericRenderPack.Id;
-                // The starfield wheels with the Dereth clock: one turn per
-                // day about the celestial pole plus ~1 degree/night of
-                // seasonal drift (dayOfYear/360) — sky.frag's rotation block.
-                var nightSkyTime = d.WorldTime;
-                skyForNightSky.NightSkyRotationTurns = () =>
-                {
-                    var cal = nightSkyTime.CurrentCalendar;
-                    int dayOfYear = (int)cal.Month
-                        * AcDream.Core.World.DerethDateTime.DaysInAMonth
-                        + (cal.Day - 1);
-                    return (float)(nightSkyTime.DayFraction + dayOfYear / 360.0);
-                };
             }
         }
 

src/AcDream.App/Rendering/Shaders/sky.frag

@@ -43,10 +43,6 @@ layout(std140, ACDREAM_UBO_SET binding = 4) uniform SkyParams {
     vec2  uUvScroll;
     float uApplyFog;
     float uSurfOpacity;
-    float uNightSkyRotationTurns; // enhanced night sky (IA-26): sky rotation
-    float uNsPadA;
-    float uNsPadB;
-    float uNsPadC;
 };
 
 struct Light {
@@ -190,50 +186,18 @@ vec3 nightSky(vec3 dir, uint seed)
 
 void main() {
     if (uParamA > 0.5) {
-        // Day/night fade from the UNIFORM ambient term only — the first
+        // The star layer's own retail lighting product (Emissive 0 ->
-        // gate's vTint signal carried the per-vertex sun-facing product and
+        // ambient + diffuse) is the day/night signal: ~0.1 at deep night,
-        // blanked stars across the whole twilight half of the sky
+        // ~1.0 at noon. Stars at full strength only under a dark sky.
-        // (2026-08-23 screenshots). Ambient is one value for the sky, so
+        float dayL = dot(vTint, vec3(0.299, 0.587, 0.114));
-        // star visibility is even everywhere; the twilight glow gets its
+        float night = 1.0 - smoothstep(0.18, 0.45, dayL);
-        // own tightly-scoped suppression below.
-        float dayL = dot(uAmbientColor, vec3(0.299, 0.587, 0.114));
-        float night = 1.0 - smoothstep(0.10, 0.32, dayL);
         if (night < 0.004) {
             // Daytime: the whole lattice would multiply to zero — skip it
             // so the enhanced sky costs nothing outside dusk-to-dawn.
             fragColor = vec4(0.0, 0.0, 0.0, 1.0);
             return;
         }
-
+        vec3 sky = nightSky(normalize(vDir), uint(uParamB));
-        vec3 d = normalize(vDir);
-
-        // Subtle twilight suppression: only the low sky (bottom ~19 deg)
-        // toward the sun's azimuth, and only while the sun term is strong
-        // (dusk/dawn) — stars near the bright horizon wash out, the rest
-        // of the sky keeps its full carpet.
-        vec3 dflat = normalize(vec3(d.xy, 0.0) + vec3(1e-5, 0.0, 0.0));
-        vec3 sflat = normalize(vec3(uSunDir.xy, 0.0) + vec3(1e-5, 0.0, 0.0));
-        float glowSide = max(dot(dflat, sflat), 0.0);
-        float lowSky = 1.0 - clamp(d.z * 3.0, 0.0, 1.0);
-        float twilight = clamp(
-            dot(uSunColor, vec3(0.299, 0.587, 0.114)) * uDiffuseFactor,
-            0.0, 1.0);
-        night *= 1.0 - 0.85 * twilight * glowSide * glowSide * lowSky;
-
-        // The sky wheels: one revolution per Dereth day about a celestial
-        // pole ~41 deg above the northern horizon (+Y north, +Z up), plus
-        // ~1 deg/night of seasonal drift folded into the turns value
-        // (dayFraction + dayOfYear/360). Rodrigues rotation of the sample
-        // direction; stars and mottle turn together.
-        const vec3 NS_POLE = vec3(0.0, 0.6598, 0.7514);
-        float ang = 6.28318530718 * fract(uNightSkyRotationTurns);
-        float ca = cos(ang);
-        float sa = sin(ang);
-        vec3 rdir = d * ca
-                  + cross(NS_POLE, d) * sa
-                  + NS_POLE * dot(NS_POLE, d) * (1.0 - ca);
-
-        vec3 sky = nightSky(rdir, uint(uParamB));
         // Additive pipeline (forced for this draw): rgb adds over the dome.
         fragColor = vec4(sky * night, 1.0);
         return;

src/AcDream.App/Rendering/Shaders/sky.vert

@@ -67,10 +67,6 @@ layout(std140, ACDREAM_UBO_SET binding = 4) uniform SkyParams {
     vec2  uUvScroll;
     float uApplyFog;      // 1 for foggable layers; raw-additive keeps fog off
     float uSurfOpacity;   // final surface opacity multiplier from the CPU
-    float uNightSkyRotationTurns; // enhanced night sky (IA-26): sky rotation
-    float uNsPadA;
-    float uNsPadB;
-    float uNsPadC;
 };
 
 // Shared SceneLighting UBO — we need uFogParams.xy (fog start/end) to

src/AcDream.App/Rendering/Shaders/spv/shaders.manifest.json

@@ -311,12 +311,12 @@
       "stages": [
         {
           "stage": "vert",
-          "sourceSha256": "80c190d5544433bd6b08810c1e5040cec5090fe91839f436728d5454ed7f3c31",
+          "sourceSha256": "9102b156bd4fd667831353640b2feee2ddde66e88579a4e425566c9b67304b64",
           "compiled": true
         },
         {
           "stage": "frag",
-          "sourceSha256": "76481dcc1a321c65308bf9c081254978ee7f12413166df5d32a1606228bdc768",
+          "sourceSha256": "e7ccdb4d5fece2ceeb48eb43aaa827424df2b68614987eeb3dfb7880dff8ea83",
           "compiled": true
         }
       ]

src/AcDream.App/Rendering/Sky/SkyRenderer.cs

@@ -106,13 +106,6 @@ public sealed partial class SkyRenderer : IDisposable
     /// </summary>
     internal Func<bool>? EnhancedNightSkyActive { get; set; }
 
-    /// <summary>
-    /// Dereth-clock rotation source for the enhanced night sky, in turns
-    /// (dayFraction + dayOfYear/360). Composition wires it to the world
-    /// time service; evaluated once per sky pass.
-    /// </summary>
-    internal Func<float>? NightSkyRotationTurns { get; set; }
-
     /// <summary>Deterministic seed for the procedural sky's hash grids —
     /// the approved-look generator's seed (gen_starfield2.py, 2026-08-23).</summary>
     private const float NightSkySeed = 11f;
@@ -216,8 +209,6 @@ public sealed partial class SkyRenderer : IDisposable
         // that FOV here, including the near-180-degree teleport transition.
         var skyProj = SkyProjection.WithDepthRange(camera.Projection, Near, Far);
 
-        _params.NightSkyRotationTurns = NightSkyRotationTurns?.Invoke() ?? 0f;
-
         // View with translation zeroed — keeps the sky at camera origin
         // regardless of camera position in the world.
         var skyView = camera.View;
@@ -735,20 +726,9 @@ public sealed partial class SkyRenderer : IDisposable
         public Vector2 UvScroll;           // 240
         public float ApplyFog;             // 248
         public float SurfOpacity;          // 252
-        /// <summary>
-        /// Whole-sky rotation in TURNS for the enhanced night sky (IA-26):
-        /// dayFraction + dayOfYear/360, so the procedural starfield wheels
-        /// once per Dereth day about the celestial pole and drifts ~1 degree
-        /// per night through the 360-day year (seasonal constellations).
-        /// Zero when the pack is inactive; the retail path never reads it.
-        /// </summary>
-        public float NightSkyRotationTurns; // 256
-        public float NsPadA;               // 260
-        public float NsPadB;               // 264
-        public float NsPadC;               // 268
 
-        /// <summary>272 — the std140 size of the block, a whole number of vec4s.</summary>
+        /// <summary>256 — the std140 size of the block, a whole number of vec4s.</summary>
-        public const int SizeInBytes = 272;
+        public const int SizeInBytes = 256;
     }
 
     private sealed class SubMeshGpu

tests/AcDream.App.Tests/Rendering/Gpu/Vk/VulkanShaderManifestTests.cs

@@ -52,8 +52,8 @@ public sealed class VulkanShaderManifestTests
             // override, retail's GameSky::Draw @0x00506FF0 rule (see
             // SkyFogRuleTests). A deliberate default-path change, reviewed
             // with the world-fog-range fix in the same commit.
-            ["sky.frag.spv"] = "83a7b4e265f7df4726d716a812ebaa74ba31ea47036bc31005cd8dc1d8981967",
+            ["sky.frag.spv"] = "e307a7f3cf84aada86db7c2859c55841a650b46732f12149986562cef0a90ca8",
-            ["sky.vert.spv"] = "988eff4e106422ca483d665ba25818e8394737a247e9bae346db3220ac31fd28",
+            ["sky.vert.spv"] = "3b51945fa4ff1be1604144df92866bdd47aade22f9dd90267591ef36adb28cde",
             ["terrain_modern.frag.spv"] = "7b3cdb01b837ed77ee20559a81c1ce5c9d5395300efcc072560ab0be3c5a1af9",
             ["terrain_modern.vert.spv"] = "9f4cb221ea6aed94a8d23af6cb8e3f3ed96c3cce6e50d135a72d3b55667b1557",
             ["ui_text.frag.spv"] = "37a281bf80441cb425eaa3ad8e0b3a43cfa21b74b60973ed4201718b9dc102df",

tests/AcDream.App.Tests/Rendering/Sky/EnhancedNightSkyRuleTests.cs

@@ -21,12 +21,7 @@ public sealed class EnhancedNightSkyRuleTests
         string code = StripLineComments(frag);
 
         Assert.Contains("if (uParamA > 0.5)", code, StringComparison.Ordinal);
-        Assert.Contains("nightSky(rdir, uint(uParamB))", code, StringComparison.Ordinal);
+        Assert.Contains("nightSky(normalize(vDir), uint(uParamB))", code, StringComparison.Ordinal);
-        // The fade must stay UNIFORM across the sky (the first gate's
-        // per-vertex vTint signal blanked the whole twilight half) and the
-        // starfield must wheel with the Dereth clock.
-        Assert.Contains("dot(uAmbientColor, vec3(0.299, 0.587, 0.114))", code, StringComparison.Ordinal);
-        Assert.Contains("fract(uNightSkyRotationTurns)", code, StringComparison.Ordinal);
         // Screen-pixel star sizing is the reason this exists — the stretched
         // texture flaw must not creep back in via a fixed-size grid, and the
         // cube-face fwidth seams must not return (the 2026-08-23 gate's

tests/AcDream.App.Tests/Rendering/SkyParamsLayoutTests.cs

@@ -8,7 +8,7 @@ namespace AcDream.App.Tests.Rendering;
 /// <summary>
 /// Campaign V slice V6e: the sky's dozen loose uniforms became one std140
 /// uniform block, and this is the test that keeps the CPU struct and the GLSL
-/// block describing the same 272 bytes.
+/// block describing the same 256 bytes.
 ///
 /// <para>It exists because the failure mode is silent. std140 gives a
 /// <c>vec3</c> 16-byte alignment while only using 12, so the block deliberately
@@ -45,12 +45,6 @@ public sealed class SkyParamsLayoutTests
     [InlineData("UvScroll", 240)]
     [InlineData("ApplyFog", 248)]
     [InlineData("SurfOpacity", 252)]
-    // IA-26: the enhanced night sky's rotation turns plus its three pad
-    // words, filling the seventeenth vec4 exactly.
-    [InlineData("NightSkyRotationTurns", 256)]
-    [InlineData("NsPadA", 260)]
-    [InlineData("NsPadB", 264)]
-    [InlineData("NsPadC", 268)]
     public void EveryMemberSitsWhereStd140PutsIt(string member, int expectedOffset)
     {
         Assert.Equal(
@@ -66,7 +60,7 @@ public sealed class SkyParamsLayoutTests
             ?.GetRawConstantValue()
             ?? throw new InvalidOperationException("SkyParams.SizeInBytes is missing."));
 
-        Assert.Equal(272, declared);
+        Assert.Equal(256, declared);
         Assert.Equal(declared, Marshal.SizeOf(SkyParamsType));
         // std140 rounds a block up to its largest member's alignment (16).
         Assert.Equal(0, declared % 16);