MONKEY (p0): skyDither cvar for the FFXGlow deband dither

The combine's dither lane was armed only by the WOW_DITHER env var. It is now
the `skyDither` cvar (0/1, default 0 = reference look; Graphics preset High
= 1) with an Advanced Graphics "Sky Dithering" checkbox row (EN + RU). The
cvar lands on `benilla_world::ffx_glow::SkyDither` (extracted) through the new
`benilla-app/src/monkey_gfx.rs` bridge; WOW_DITHER=1 still forces it on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

LIGHTING.md

@@ -24,6 +24,7 @@ behind each constant.
 | Moon shadows | at night the same shadow rig re-aims at the moon and casts a faint shadow; dims only the night sky term, never point lights | `moonShadowStrength` |
 | Ground-effect spells | Flamestrike, Rain of Fire, Consecration, Flare and fire traps light the ground for their duration; frost and nature areas stay dark | `spellLightGain` |
 | Volumetric fog | near-field haze that converges on the zone fog colour (clear within 10 yd, full by 150 yd; mistier at dawn and in bad weather, faint indoors) and sun/moon light shafts through gaps, sampled from the shadow map; own fullscreen pass after the main pass (`benilla-app/src/volumetric_fog.rs`) | Advanced Graphics → Volumetric Fog (Off/Low/High), cvar `volumetricFog`, env `WOW_VOLFOG=0\|1\|2` |
+| Sky dithering | a faint screen-space dither in the FFXGlow combine so smooth sky and fog gradients do not band (MONKEY p0; was env-only) | Advanced Graphics → Sky Dithering, cvar `skyDither` 0/1 (default 0, Graphics preset High = 1), env `WOW_DITHER=1` still forces it on; bridge in `benilla-app/src/monkey_gfx.rs` |
 | Night and interior level | global dimming of the night sky term and of interior ambient | `nightGain`, `interiorGain`, `interiorBakeFloor` |
 
 Players reach all of it from **Options -> Advanced Graphics** (a Lighting Quality preset Off / Low / Medium / High plus the individual rows; Off is the original client look). The dev build has a panel for all of it: **Ctrl+Shift+D → Lighting & shadows**, with Dim / Default /

crates/benilla-app/assets/ui/OptionsFrame.xml

@@ -519,6 +519,8 @@
                 spellLights = "Spell Lights",
                 nightDarkness = "Night Darkness",
                 interiorDarkness = "Interior Darkness",
+                -- MONKEY (p0 skyDither)
+                skyDither = "Sky Dithering",
                 yards = "%d yd",
                 tips = {
                     LIGHTING_QUALITY =
@@ -611,6 +613,10 @@
                         "Scales interior fixture light and room ambient, including the light from "
                         .. "lamps and candles. Lower values make both dimmer.\n\n"
                         .. "1.0 leaves these inputs unchanged. Free at any setting.",
+                    -- MONKEY (p0 skyDither)
+                    SKY_DITHER =
+                        "Adds a faint noise to the final image so smooth sky and fog gradients do not "
+                        .. "break into visible bands. Off is the original client's look. Practically free.",
                 },
             },
             ruRU = {
@@ -643,6 +649,8 @@
                 spellLights = "Свет от заклинаний",
                 nightDarkness = "Темнота ночи",
                 interiorDarkness = "Темнота помещений",
+                -- MONKEY (p0 skyDither)
+                skyDither = "Дизеринг неба",
                 yards = "%d ярд.",
                 tips = {
                     LIGHTING_QUALITY =
@@ -743,6 +751,11 @@
                         "Масштабирует свет светильников и фоновое освещение помещений, включая "
                         .. "свет ламп и свечей. Меньшие значения ослабляют и то и другое.\n\n"
                         .. "1.0 оставляет эти составляющие без изменений. Ничего не стоит при любом значении.",
+                    -- MONKEY (p0 skyDither)
+                    SKY_DITHER =
+                        "Добавляет едва заметный шум в итоговое изображение, чтобы плавные переходы цвета "
+                        .. "неба и тумана не распадались на полосы. Выключено — вид оригинального клиента. "
+                        .. "Почти ничего не стоит.",
                 },
             },
         }
@@ -801,6 +814,8 @@
                 "RowInteriorLight", "RowInteriorShadows", "RowExteriorShadows", "RowTorchSoft",
                 "RowFireLight", "RowFireFlicker", "RowSpellLights", "RowLavaGlow",
                 "RowNightDarkness", "RowInteriorDarkness",
+                -- MONKEY (p0 skyDither)
+                "RowSkyDither",
             },
             -- Player Guild Names is a child of Player Names, as in 1.12 (l.702-708).
             Nameplates = {
@@ -2827,6 +2842,18 @@
                                                 OptionsSliderRow_Setup(self, 0.2, 1.5, 0.05, "darkness")
                                             </OnLoad></Scripts>
                                         </Frame>
+                                        <!-- MONKEY (p0 skyDither): the combine's deband dither. -->
+                                        <Frame name="$parentRowSkyDither" inherits="OptionsCheckboxRowTemplate">
+                                            <Anchors>
+                                                <Anchor point="TOPLEFT" relativeTo="$parentRowInteriorDarkness" relativePoint="BOTTOMLEFT"><Offset><AbsDimension x="0" y="-9"/></Offset></Anchor>
+                                                <Anchor point="TOPRIGHT" relativeTo="$parentRowInteriorDarkness" relativePoint="BOTTOMRIGHT"><Offset><AbsDimension x="0" y="-9"/></Offset></Anchor>
+                                            </Anchors>
+                                            <Scripts><OnLoad>
+                                                OptionsRow_OnLoad(self, "skyDither",
+                                                    BENILLA_ADVGFX.skyDither,
+                                                    "BENILLA_TOOLTIP_SKY_DITHER")
+                                            </OnLoad></Scripts>
+                                        </Frame>
                                     </Frames>
                                     <!-- The poll (see AdvGfx_OnUpdate): this is the one page whose
                                          settings move from outside it — the Lighting Quality row

crates/benilla-app/src/cvars.rs

@@ -921,6 +921,13 @@ pub(crate) const REGISTERED: &[Registered] = &[
     ),
     // MONKEY (volumetric fog): saved live tier; capture override stays session-only.
     ours("volumetricFog", "1", "benilla's own: near-field volumetric fog, 0 Off / 1 Low / 2 High"),
+    // MONKEY (p0 skyDither): the FFXGlow combine's deband dither (was env WOW_DITHER only).
+    // Default 0 = the reference look; the Graphics preset's High sets 1.
+    ours(
+        "skyDither",
+        "0",
+        "benilla's own: faint screen dither against sky and fog banding, 0 Off / 1 On",
+    ),
     ours(
         "waterQuality",
         "1",
@@ -3702,6 +3709,11 @@ mod tests {
         |app| {
             app.add_observer(crate::video::on_cvar);
         },
+        // MONKEY (p0 graphics programme)
+        |app| {
+            app.init_resource::<benilla_world::ffx_glow::SkyDither>();
+            app.add_observer(crate::monkey_gfx::on_cvar);
+        },
         |app| {
             app.add_observer(crate::player::camera::on_cvar);
         },

crates/benilla-app/src/game_plugins.rs

@@ -245,6 +245,8 @@ impl PluginGroup for GamePlugins {
             .add(crate::dynamic_interior::DynamicInteriorPlugin)
             // MONKEY (volumetric fog): bridge the live setting to Bevy.
             .add(crate::volumetric_fog::VolumetricFogPlugin)
+            // MONKEY (p0 graphics programme): the programme's cvar bridges (skyDither, ...).
+            .add(crate::monkey_gfx::MonkeyGfxPlugin)
             // The realmlist (decision 1667) — the logon address the login screen edits. Same reason as
             // VideoPlugin above: it is a CVar knob, so its resource has to exist before `load_config`.
             .add(crate::realmlist::RealmlistPlugin)

crates/benilla-app/src/lib.rs

@@ -74,6 +74,8 @@ mod doodad_events;
 /// MONKEY (dynamic interiors): the cvar → benilla-world bridge for the fixture-lit interior lane.
 // MONKEY (volumetric fog): optional near-field atmosphere plugin.
 mod volumetric_fog;
+// MONKEY (p0 graphics programme): the programme's cvar bridges (skyDither, ...).
+mod monkey_gfx;
 mod dynamic_interior;
 mod entities;
 mod fishing_line;

crates/benilla-app/src/monkey_gfx.rs

@@ -0,0 +1,30 @@
+//! MONKEY (p0 graphics programme): the cvar bridges of the graphics programme's own settings, each
+//! landing on the benilla-world resource its renderer reads. One observer, one arm per cvar;
+//! lanes add their rows here rather than to `video.rs`'s reference block.
+//!
+//! | cvar | values | default | Graphics preset High | resource |
+//! |---|---|---|---|---|
+//! | `skyDither` | 0 Off / 1 On | 0 | 1 | `benilla_world::ffx_glow::SkyDither` |
+
+use bevy::prelude::*;
+use benilla_world::ffx_glow::SkyDither;
+
+/// The programme's cvar observer (registered by [`MonkeyGfxPlugin`]).
+pub(crate) fn on_cvar(ev: On<crate::cvars::CvarChanged>, mut dither: ResMut<SkyDither>) {
+    if ev.key().as_str() == "skydither" {
+        let want = ev.num() >= 0.5;
+        if dither.0 != want {
+            dither.0 = want;
+        }
+    }
+}
+
+/// Registers the programme's cvar bridges. Must be added before `CvarPlugin` so the saved values
+/// applied at Startup reach it (the edge `game_plugins.rs` documents for every knob plugin).
+pub(crate) struct MonkeyGfxPlugin;
+
+impl Plugin for MonkeyGfxPlugin {
+    fn build(&self, app: &mut App) {
+        app.init_resource::<SkyDither>().add_observer(on_cvar);
+    }
+}

crates/benilla-world/src/ffx_glow.rs

@@ -684,12 +684,18 @@ fn prepare_textures(
     }
 }
 
-/// `WOW_DITHER=1` arms the combine's deband dither (`ffx.lane.w`). Deviation, opt-in, off by
-/// default: the reference's 8-bit framebuffer is undithered, but a smooth gradient under slow
-/// motion steps visibly at 1/255. Bevy's own dither never runs under `Tonemapping::None`.
-fn dither_armed() -> f32 {
-    static ON: std::sync::OnceLock<bool> = std::sync::OnceLock::new();
-    match *ON.get_or_init(|| std::env::var_os("WOW_DITHER").is_some()) {
+/// MONKEY (p0 skyDither): the combine's deband dither (`ffx.lane.w`), the `skyDither` cvar
+/// (Advanced Graphics -> Sky Dithering, 0/1, default 0). Deviation, opt-in: the reference's 8-bit
+/// framebuffer is undithered, but a smooth gradient under slow motion steps visibly at 1/255.
+/// Bevy's own dither never runs under `Tonemapping::None`. benilla-app's settings bridge writes it.
+#[derive(Resource, Clone, Copy, Default, PartialEq, Eq, Debug, ExtractResource)]
+pub struct SkyDither(pub bool);
+
+/// `WOW_DITHER=1` still arms the dither for a session (it used to be the only switch); otherwise
+/// the live [`SkyDither`] decides.
+fn dither_armed(cvar: bool) -> f32 {
+    static ENV: std::sync::OnceLock<bool> = std::sync::OnceLock::new();
+    match cvar || *ENV.get_or_init(|| std::env::var_os("WOW_DITHER").is_some()) {
         true => 1.0,
         false => 0.0,
     }
@@ -713,7 +719,7 @@ fn combine_uniform(
         zone_gain * glow.gain_scale,
         feed.death,
         feed.haze,
-        dither_armed(),
+        0.0, // MONKEY (p0 skyDither): the dither arm, set by `live_combine` from [`SkyDither`]
         wave.phase1,
         wave.phase2,
         0.0,
@@ -906,6 +912,9 @@ fn live_combine(world: &World, glow: &FfxGlow) -> ([f32; 8], bool) {
         glow,
         wave,
     );
+    // MONKEY (p0 skyDither): the dither lane, from the cvar (or the old env switch).
+    let mut uniform = uniform;
+    uniform[3] = dither_armed(world.get_resource::<SkyDither>().is_some_and(|d| d.0));
     (uniform, wave_armed(glow.state, wave, death))
 }
 
@@ -1090,6 +1099,8 @@ impl Plugin for FfxGlowPlugin {
             .init_resource::<GlueFfx>()
             .init_resource::<FfxHazeMix>()
             .init_resource::<FfxWave>()
+            // MONKEY (p0 skyDither)
+            .init_resource::<SkyDither>()
             .add_plugins((
                 ExtractComponentPlugin::<FfxGlow>::default(),
                 ExtractComponentPlugin::<FfxBackdrop>::default(),
@@ -1098,6 +1109,7 @@ impl Plugin for FfxGlowPlugin {
                 ExtractResourcePlugin::<GlueFfx>::default(),
                 ExtractResourcePlugin::<FfxHazeMix>::default(),
                 ExtractResourcePlugin::<FfxWave>::default(),
+                ExtractResourcePlugin::<SkyDither>::default(),
             ))
             .add_systems(
                 Update,

crates/benilla-world/src/shaders/ffx_glow.wgsl

@@ -63,7 +63,7 @@ fn srgb_to_linear(c: vec3<f32>) -> vec3<f32> {
     return select(hi, lo, c <= vec3<f32>(0.04045));
 }
 
-// Deviation, opt-in (`WOW_DITHER=1`): a dither against banding, which the reference's 8-bit
+// Deviation, opt-in (MONKEY p0: cvar `skyDither`, or `WOW_DITHER=1`): a dither against banding, which the reference's 8-bit
 // framebuffer lacks. The hash is Bevy's `screen_space_dither`, copied here because Bevy applies
 // it only in the tonemapping pass that `Tonemapping::None` skips.
 fn screen_space_dither(frag_coord: vec2<f32>) -> vec3<f32> {