HD water darker, without the vanilla texture (fork patch 20)

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

docs/HD-RENDERER.md

@@ -50,13 +50,29 @@ cd .. && rm -f horizon-patches/*.patch && git -C horizon format-patch -q $(cat H
    (`shadow_casters`: без оверлеев 4/9/10/40 — 40 это светящиеся модели мода).
 2. **G-буфер** (свой depth): albedo `Rgba8Unorm` (a = эмиссия), нормаль `Rgba16Float` (мировая, из `dpdx/dpdy`),
    уровни света `Rgba8Unorm` (x = небо, y = блоки — сырые координаты лайтмапа /240). Террейн + дальние LOD-тайлы +
-   сущности. Вода/полупрозрачное в G-буфер **не** попадает (идёт ванильным путём) — см. план.
-3. **GTAO** (полразрешения, `Rg16Float`: окклюзия, дистанция) + depth-aware блюр 5×5. 3 среза × 5 шагов, радиус
+   сущности. Полупрозрачное в G-буфер **не** попадает (идёт ванильным путём); вода — отдельный путь, см. п. 3 и «Вода».
+3. **Вода** (`water_pass`, только если на экране есть полупрозрачные секции, нет `frame.underwater` и не `HORIZON_HD_WATER=0`):
+   те же секции ещё раз с `fs_water` (terrain.wgsl), который отбрасывает всё, кроме слоёв спрайтов `water_still`/`water_flow`
+   (номера слоёв передаются в `Renderer::new` из `sprite_layers` и ставятся override-константами `WATER_STILL/WATER_FLOW`; стекло,
+   лёд и прочее остаются ванильными). Цели: цвет (спрайт × биомный тинт, a = свет блоков, `Rgba16Float`), нормаль грани (a = свет неба,
+   `Rgba8Unorm`) и собственная глубина воды (`Depth32Float`, 0 = воды нет; тест глубины только среди воды, перекрытие
+   землёй решают потребители). Пайплайны `gbuffer_water` (секции) и `flat.water` (flat-путь).
+3a. **GTAO** (полразрешения, `Rg16Float`: окклюзия, дистанция) + depth-aware блюр 5×5. 3 среза × 5 шагов, радиус
    1.8 блока, шум IGN по кадру. Сила — `HdFrame.ambient.w` (`HORIZON_HD_AO=<число>`, 0 = выкл).
-4. **Освещение** `fs_light` → `lit` (HDR): `max(небо·ambient.x, блоки·ambient.y)·AO + солнце·N·L·тень + точечные
+4. **Освещение** `fs_light` → `lit` (HDR): пиксель — вода, если `water_depth >= g` и перед водой в мировой глубине ничего нет
+   (`d - wd <= 0.2%`); тогда освещается **дно** по данным G-буфера (одна выборка тени, без AO), а в альфу `lit` пишется 0.5 (признак воды). `max(небо·ambient.x, блоки·ambient.y)·AO + солнце·N·L·тень + точечные
    источники` × albedo + эмиссия; затем ванильный туман заново, объёмные лучи (14 шагов, Henyey-Greenstein g=0.6),
    ореолы вокруг источников. Точечные источники — по тайлам 16×16 (`tile_lists`, буфер `tiles`: на тайл 4 слова —
    начало/длина списка для поверхностей и для ореолов, потом индексы; переполнение → «все источники»).
+4a. **Композит воды** `fs_water` (`hd.water_composite`, `lit` → `lit_water`, дальше везде `hd.lit_view()`; на пикселях без воды копия).
+   Волны — сумма 10 синусоид в мировых координатах (векторы — целые кратные 2π/256, скорости — целые циклы за 600 с: период 256 блоков
+   и 10 минут, не «плывут» с камерой; мелкие волны гасятся по размеру пикселя против мерцания); нормаль = нормаль грани + градиент
+   (только на горизонтальных гранях). Преломление: смещение луча относительно плоской воды, выборка `lit` по uv со сдвигом (отбраковка
+   по глубине: не берутся банк/сущности перед водой); толщина = расстояние от поверхности до дна; поглощение `exp(-(1-цвет)·0.8·(t+0.3))`
+   + рассеяние цветом воды при свете «объёма» (лайтмап + солнце с тенью). Отражение: SSR по глубине G-буфера (24 шага, растущие,
+   джиттер IGN по кадру, 5 шагов бинарного уточнения, толщина `0.4+0.08·s`), при промахе — небо/туман (`sky_color`, `fog_color`, тусклее
+   под навесом). Френель Шлика F0=0.02 (SSR пропускается при F<0.04: взгляд вниз), блик солнца GGX (a=0.05) × тень, туман поверх.
+   Подводный вид и `HORIZON_HD_WATER=0` — композит и проход воды не работают, `lit` как раньше.
 5. **Пост-проход мода** `lit` → `fx` (`effects.wgsl`: взрывы, дым, вспышки, свечение; при HD его собственная
    «подсветка огнём» выключена — свет даёт HD).
 6. **TAA** — после пост-прохода мода (`fx`, либо `lit` без него), до bloom: история пинг-понгом, в альфе истории —
@@ -88,10 +104,13 @@ Bind groups кэшируются и пересоздаются только пр
 | 10, 11 | лайтмап, линейный сэмплер |
 | 12 | тайлы источников (storage) |
 | 13 | AO |
+| 14 | глубина воды (`water_depth`) |
 
 `HdFrame` (Rust и WGSL держать в синхроне!): `inverse_view_proj`, `resolution` (w, h, 1/w, 1/h), `params` (число
 источников, экспозиция, bloom, счётчик кадров), `cascades[2]`, `sun` (направление, сила), `sun_color` (rgb, ночь),
-`fog_color`, `fog`, `ambient` (тень неба, блоки, плотность воздуха, AO), `shadow` (вкл, R0, R1, тайлов в строке).
+`fog_color`, `fog`, `ambient` (тень неба, блоки, плотность воздуха, AO), `shadow` (вкл, R0, R1, тайлов в строке), `prev_view_proj`, `taa`, `taa_params`, `view_proj` (с джиттером, для лучей воды), `water` (x: эффект идёт, y: секунды волн mod 600, zw: камера x, z mod 256), `sky_color` (w: есть небо).
+
+Композит воды (`WATER`, group 0): 0 `HdFrame`, 1 `lit`, 2 глубина G-буфера, 3 цвет воды, 4 нормаль воды, 5 глубина воды, 6–7 тени, 8 лайтмап, 9 сэмплер.
 
 ## Как проверять
 
@@ -146,6 +165,7 @@ TAAU (2560×1440, GPU avg кадр, сцена Polygon): scale 1.0 — 18.1 мс
 | TAA: джиттер Halton(2,3) ×16, перепроекция по глубине и сдвигу камеры, variance clip в YCoCg, история Catmull-Rom 0.9, лёгкий шарп в tonemap (`HORIZON_HD_TAA=0` — выкл) | готово | патч 16 |
 | TAAU: мир в `HORIZON_HD_SCALE` (0.25–1, по умолчанию 1 = как раньше), восстановление в TAA-проходе `fs_taau`; без LOD-bias текстур (не доступен) | готово | патч 18 |
 | Исправлено мерцание теней у игрока: ближний каскад терял секции в кадры, когда дальний держится; держимая матрица дальнего каскада сдвигается на шаг камеры; у растений (наклонные квады) нормаль «вверх», а не к камере; TAA держит 94% истории в покое | готово | патч 18 |
+| Вода: проход `fs_water`, преломление, SSR, Френель, блик (`HORIZON_HD_WATER=0` — выкл) | готово | патч 19 (+20: без ванильной текстуры на поверхности, цвет темнее и глубже) |
 | API моделей по хэндлам (#30, уровень API 11: `model-id`, `model-generation`, `set-models-by-id`) | готово | патч 17 |
 
 ## План (по порядку) и ТЗ
@@ -158,7 +178,7 @@ TAAU (2560×1440, GPU avg кадр, сцена Polygon): scale 1.0 — 18.1 мс
    масштаба (`HORIZON_HD_SCALE` или поле в `HdSettings`). Цель: при 0.67 картинка близка к нативной, FPS заметно
    выше. Альтернатива на Mac — MetalFX через wgpu-hal (нативный код, только Metal) — отдельной опцией потом. DLSS
    нереален для нашей цели (только NVIDIA через Streamline, нет в wgpu).
-2. **Вода**: отдельный G-буфер-путь для воды (маска + нормаль с анимированными волнами), SSR (трассировка по
+2. **Вода** — СДЕЛАНО (патч 19, см. «Вода» ниже). Исходное ТЗ: отдельный G-буфер-путь для воды (маска + нормаль с анимированными волнами), SSR (трассировка по
    глубине, откат на небо/туман), преломление (смещение по нормали), затухание по глубине воды (цвет биома),
    блики солнца (GGX-подобный), френель. Подводный вид не ломать (`frame.underwater`).
 3. **Небо и атмосфера**: рассеяние Рэлея/Ми (предвычисленная LUT пропускания и небесного цвета в маленькой
@@ -174,6 +194,20 @@ TAAU (2560×1440, GPU avg кадр, сцена Polygon): scale 1.0 — 18.1 мс
 10. **RT-пресет**: `wgpu` `EXPERIMENTAL_RAY_QUERY` (Vulkan/DX12/Metal M3+), BLAS по секциям, ray-query тени и
     отражения, затем GI. Отдельный пресет, HD остаётся.
 
+## Вода (патч 19): что знать преемнику
+
+- Тайминги проходов: `hd water` (геометрия воды; на Metal его метка часто 0 — работа учитывается в соседних проходах) и `hd water composite`.
+  Замеры 2560×1440, Hills, река на ~40% экрана, M5 (шумно: у меня GPU делят браузеры): композит 0.8–2 мс, `hd lighting` на 2–3 мс
+  выше, чем без воды (теперь освещается дно под водой — раньше эти пиксели были ванильными); всего вода ≈ +3 мс при большой воде
+  на экране, около 0.5–1 мс при малой. Цель «≤ 2 мс» при полной реке не достигнута. Идеи: отражения в полразрешения (с учётом маски воды
+  на границе), SSR только при F>0.04 уже есть, ужать освещение дна (без точечных источников на глубине > N блоков).
+- Вода находится по слоям спрайтов. LOD-тайлы воды (`lod/mesh.rs`) идут тем же путём, если их слой — water_still; вода из resource pack с
+  другим именем спрайта не распознается (останется ванильной). `water_overlay` (боковые грани у стекла) не трогаем.
+- Стекло/частицы/лёд перед водой: проверка `d - wd` возвращает ванильный вид пикселя (вода под стеклом без эффекта).
+- Известные ограничения: отражается только то, что есть на экране (и только непрозрачное: листва — да, вода/стекло — нет); дождь на воде,
+  пена у берега, подводная каустика не сделаны; ночью вода слегка ярче неба (нужно привязать к модели неба — п. 4 плана «Небо»); отражение
+  солнечного диска — только блик GGX (без диска в SSR). Проверка мерцания на реке: разница двух скриншотов ≈1.6% пикселей >20/255 (норма ~2%).
+
 ## Правила
 
 - Ничего не ломать в `off`/`on`; HD выключен — код HD не работает вовсе (`hd = None`).

horizon-patches/0001-Mod-API-AirDef-fork-world-models-client-particles-so.patch

@@ -1,7 +1,7 @@
 From 3de7a6875140a107e28563cc44489b55f5794517 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 12:37:45 +0300
-Subject: [PATCH 01/18] Mod API (AirDef fork): world models, client particles,
+Subject: [PATCH 01/20] Mod API (AirDef fork): world models, client particles,
  sounds, ground heights
 
 render.set-models draws block models with an interpolated pose per id;

horizon-patches/0002-cargo-horizon-mod-report-particles-and-sounds.patch

@@ -1,7 +1,7 @@
 From a6d64e6415bf618539af464e521091e72b72d72f Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 12:39:45 +0300
-Subject: [PATCH 02/18] cargo-horizon-mod: report particles and sounds
+Subject: [PATCH 02/20] cargo-horizon-mod: report particles and sounds
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
 ---

horizon-patches/0003-Mod-API-AirDef-fork-full-screen-post-pass-for-mods.patch

@@ -1,7 +1,7 @@
 From ee79b3562feebe51959a01f1585a9e85bd53ccb5 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 13:33:10 +0300
-Subject: [PATCH 03/18] Mod API (AirDef fork): full-screen post pass for mods
+Subject: [PATCH 03/20] Mod API (AirDef fork): full-screen post pass for mods
 
 render.set-post compiles a mod's WGSL after a prelude (camera matrices,
 time, 256 vec4 of params, the world's colour and depth) and runs it after

horizon-patches/0004-Mod-models-draw-far-models-as-scaled-impostors-past-.patch

@@ -1,7 +1,7 @@
 From 2b137dbbedd540daeebc7f5e387847aeb56a1355 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 22:09:30 +0300
-Subject: [PATCH 04/18] Mod models: draw far models as scaled impostors past
+Subject: [PATCH 04/20] Mod models: draw far models as scaled impostors past
  the far plane, cull at 4096
 
 ---

horizon-patches/0005-Mod-cameras-render.set-views-draws-the-world-from-ot.patch

@@ -1,7 +1,7 @@
 From c8ebca6e0af68630e65211844b34d25c5b985c03 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 22:31:00 +0300
-Subject: [PATCH 05/18] Mod cameras: render.set-views draws the world from
+Subject: [PATCH 05/20] Mod cameras: render.set-views draws the world from
  other points into pictures that HUD view shapes show (API level 9)
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0006-Mods-more-fuel-per-tick-and-per-event-AirDef-plans-r.patch

@@ -1,7 +1,7 @@
 From 8d2261fc4f8072c32e454139cfea7a8c0cd9d664 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 23:08:21 +0300
-Subject: [PATCH 06/18] Mods: more fuel per tick and per event (AirDef plans
+Subject: [PATCH 06/20] Mods: more fuel per tick and per event (AirDef plans
  raids)
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0007-Mod-cameras-up-to-1920x1080-full-screen-replays.patch

@@ -1,7 +1,7 @@
 From 6c548de34def8e4a624d734243418090798bd16a Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Wed, 28 Oct 2026 23:25:29 +0300
-Subject: [PATCH 07/18] Mod cameras up to 1920x1080 (full-screen replays)
+Subject: [PATCH 07/20] Mod cameras up to 1920x1080 (full-screen replays)
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
 ---

horizon-patches/0008-Mod-cameras-distant-terrain-tiles-fog-measured-from-.patch

@@ -1,7 +1,7 @@
 From 9b9e93269d67401cc620567a884d5ce97f68d76e Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 11:15:11 +0300
-Subject: [PATCH 08/18] Mod cameras: distant terrain tiles, fog measured from
+Subject: [PATCH 08/20] Mod cameras: distant terrain tiles, fog measured from
  the camera, no impostors while one is shown
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0009-Mods-game.world-id-so-mods-keep-state-per-world-API-.patch

@@ -1,7 +1,7 @@
 From 065d9fa02966238a5bd9ff460392a1a809db0b11 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 11:25:45 +0300
-Subject: [PATCH 09/18] Mods: game.world-id, so mods keep state per world (API
+Subject: [PATCH 09/20] Mods: game.world-id, so mods keep state per world (API
  level 9)
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0010-cargo-horizon-mod-trial-runs-behind-feature-full-so-.patch

@@ -1,7 +1,7 @@
 From 1bf28135fd9a31f837323dc3a8d81ed73343d816 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 12:01:08 +0300
-Subject: [PATCH 10/18] cargo-horizon-mod: trial runs behind feature full, so a
+Subject: [PATCH 10/20] cargo-horizon-mod: trial runs behind feature full, so a
  packing-only tool skips wasmtime
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0011-HD-lighting-G-buffer-pass-per-pixel-mod-point-lights.patch

@@ -1,7 +1,7 @@
 From 0a56f5616df4699588cbcc529d4720661baa810f Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 13:18:43 +0300
-Subject: [PATCH 11/18] HD lighting: G-buffer pass, per-pixel mod point lights
+Subject: [PATCH 11/20] HD lighting: G-buffer pass, per-pixel mod point lights
  in HDR, bloom and tone curve; render.set-lights and render.set-lighting (API
  level 10)
 

horizon-patches/0012-HD-lighting-stage-2-sun-and-moon-shadow-cascades-the.patch

@@ -1,7 +1,7 @@
 From 9ebf0031fe9ba6b7f02afb26e4fd3a1ba4ddb0d0 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 13:59:43 +0300
-Subject: [PATCH 12/18] HD lighting stage 2: sun and moon shadow cascades, the
+Subject: [PATCH 12/20] HD lighting stage 2: sun and moon shadow cascades, the
  world relit (sun by face angle and shadow, sky and block light through the
  lightmap), light shafts and halos, fog over it again, a light colour grade
 

horizon-patches/0013-HD-bind-groups-cached-until-a-resize-or-a-new-source.patch

@@ -1,7 +1,7 @@
 From 7a5a38f68923aec62f10bfa0df50b436474ed612 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 16:19:53 +0300
-Subject: [PATCH 13/18] HD: bind groups cached until a resize or a new source,
+Subject: [PATCH 13/20] HD: bind groups cached until a resize or a new source,
  shadow passes draw only the entities that cast shadows
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0014-HD-lights-culled-per-16x16-tile-surface-and-halo-lis.patch

@@ -1,7 +1,7 @@
 From 8020811e57d4b5a9ea1cd72d30ce859dc5095d35 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 16:25:44 +0300
-Subject: [PATCH 14/18] HD: lights culled per 16x16 tile (surface and halo
+Subject: [PATCH 14/20] HD: lights culled per 16x16 tile (surface and halo
  lists built on the CPU), a naga test for the lighting shaders
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0015-HD-GPU-time-per-pass-in-the-F3-timing-list-half-reso.patch

@@ -1,7 +1,7 @@
 From 72d3fddfea329e578162656151350f0aa2efd323 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 16:43:36 +0300
-Subject: [PATCH 15/18] HD: GPU time per pass in the F3 timing list,
+Subject: [PATCH 15/20] HD: GPU time per pass in the F3 timing list,
  half-resolution GTAO with a depth-aware blur
 
 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

horizon-patches/0016-HD-shadows-draw-only-sun-facing-quads-and-skip-burie.patch

@@ -1,7 +1,7 @@
 From 1fd83a821bf270879d8ece5aa583f200ed920d89 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 17:02:02 +0300
-Subject: [PATCH 16/18] HD: shadows draw only sun-facing quads and skip buried
+Subject: [PATCH 16/20] HD: shadows draw only sun-facing quads and skip buried
  sections, the far cascade every second frame; TAA (Halton jitter,
  reprojection by depth, YCoCg variance clipping) before bloom
 

horizon-patches/0017-Mods-model-handles-render.model-id-model-generation-.patch

@@ -1,7 +1,7 @@
 From 1502d359d599228fe0f44ce6b99a3fded2ac5ea0 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 17:02:02 +0300
-Subject: [PATCH 17/18] Mods: model handles (render.model-id, model-generation,
+Subject: [PATCH 17/20] Mods: model handles (render.model-id, model-generation,
  set-models-by-id; API level 11) so mods send no model names each tick;
  clear-post and set-lighting documented
 

horizon-patches/0018-HD-temporal-upscaling-HORIZON_HD_SCALE-world-G-buffe.patch

@@ -1,7 +1,7 @@
 From 0f9d99b8ad3e4b72e621d84c2396cf1d3d2b7a33 Mon Sep 17 00:00:00 2001
 From: chexit <chexit@duck.com>
 Date: Thu, 29 Oct 2026 17:19:57 +0300
-Subject: [PATCH 18/18] HD: temporal upscaling (HORIZON_HD_SCALE: world,
+Subject: [PATCH 18/20] HD: temporal upscaling (HORIZON_HD_SCALE: world,
  G-buffer and lighting at a lower size, rebuilt to the window in the TAA
  pass); fix flickering shadows near the player (the near cascade lost its
  sections on frames the far one was held, the held far matrix ignored the

horizon-patches/0019-HD-water-its-own-pass-colour-normal-depth-the-floor-.patch

@@ -0,0 +1,982 @@
+From 38250c4392e27d5700842ca6ee47291dd1831b72 Mon Sep 17 00:00:00 2001
+From: chexit <chexit@duck.com>
+Date: Thu, 29 Oct 2026 17:47:52 +0300
+Subject: [PATCH 19/20] HD water: its own pass (colour, normal, depth), the
+ floor under it lit, a composite with world-space waves, refraction with depth
+ absorption in the biome colour, screen-space reflections, Fresnel and a
+ shadowed sun glint (HORIZON_HD_WATER=0 to switch off)
+
+Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
+---
+ crates/horizon-client/src/game.rs      |   9 +
+ crates/horizon-client/src/gfx.rs       | 109 +++++-
+ crates/horizon-client/src/gfx/flat.rs  |   4 +
+ crates/horizon-client/src/gfx/hd.rs    | 497 ++++++++++++++++++++++++-
+ crates/horizon-client/src/terrain.wgsl |  19 +
+ 5 files changed, 627 insertions(+), 11 deletions(-)
+
+diff --git a/crates/horizon-client/src/game.rs b/crates/horizon-client/src/game.rs
+index 3a11ee283..5a173977f 100644
+--- a/crates/horizon-client/src/game.rs
++++ b/crates/horizon-client/src/game.rs
+@@ -14658,6 +14658,14 @@ fn build_renderer(
+         prepared,
+         previous,
+         api,
++        // AirDef fork, HD water: the layers of the water sprites.
++        ["water_still", "water_flow"].map(|name| {
++            assets
++                .sprite_layers
++                .get(&format!("minecraft:block/{name}"))
++                .copied()
++                .unwrap_or(0xffff)
++        }),
+     ))?;
+     renderer.hud.sprite_animations = atlas
+         .sprite_animations
+@@ -14717,6 +14725,7 @@ fn loading_renderer(
+         None,
+         previous,
+         api,
++        [0xffff; 2],
+     ))?;
+     if let Some(atlas) = atlas {
+         renderer.hud.sprite_animations = atlas
+diff --git a/crates/horizon-client/src/gfx.rs b/crates/horizon-client/src/gfx.rs
+index b85c6e269..f9dab8abf 100644
+--- a/crates/horizon-client/src/gfx.rs
++++ b/crates/horizon-client/src/gfx.rs
+@@ -564,6 +564,8 @@ pub struct Renderer {
+     mod_views: Option<mod_views::Views>,
+     /// AirDef fork: the HD lighting's G-buffer pipelines (terrain, entities) and its targets.
+     gbuffer_terrain: wgpu::RenderPipeline,
++    /// The water quads alone into the HD water targets (section draws; `flat.water` for flat ones).
++    gbuffer_water: wgpu::RenderPipeline,
+     gbuffer_entity: wgpu::RenderPipeline,
+     /// The HD sun shadows: depth only, from the light, and the sections in its farther cascade.
+     shadow_terrain: wgpu::RenderPipeline,
+@@ -1083,6 +1085,7 @@ impl Renderer {
+         prepared: Option<PreparedTextures>,
+         previous: Option<&Self>,
+         api: GraphicsApi,
++        water_layers: [u32; 2],
+     ) -> Result<Self> {
+         let split = sprite_split();
+         if layers > split * SPRITE_ARRAYS {
+@@ -1205,6 +1208,13 @@ impl Renderer {
+             ("SPRITE_ARRAYS", f64::from(sprite_arrays)),
+             ("SPRITE_SPLIT", f64::from(split)),
+         ];
++        // AirDef fork, HD water: the sprite layers terrain.wgsl's fs_water takes for water.
++        let water_constants = [
++            ("SPRITE_ARRAYS", f64::from(sprite_arrays)),
++            ("SPRITE_SPLIT", f64::from(split)),
++            ("WATER_STILL", f64::from(water_layers[0])),
++            ("WATER_FLOW", f64::from(water_layers[1])),
++        ];
+         let bindings = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+             label: Some("Horizon terrain bindings"),
+             entries: &[
+@@ -1420,6 +1430,55 @@ impl Renderer {
+             multiview_mask: None,
+             cache: None,
+         });
++        // AirDef fork, HD water: only the water quads (`fs_water`), into the colour and normal
++        // targets and the water's own depth; `vertex` is the section or the flat vertex stage.
++        let water_targets = [
++            Some(wgpu::ColorTargetState {
++                format: hd::WATER_TINT,
++                blend: None,
++                write_mask: wgpu::ColorWrites::ALL,
++            }),
++            Some(wgpu::ColorTargetState {
++                format: hd::WATER_NORMAL,
++                blend: None,
++                write_mask: wgpu::ColorWrites::ALL,
++            }),
++        ];
++        let water_pipeline =
++            |layout: &wgpu::PipelineLayout,
++             label: &str,
++             vertex: &str,
++             buffers: &[Option<wgpu::VertexBufferLayout<'_>>]| {
++                device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
++                    label: Some(label),
++                    layout: Some(layout),
++                    vertex: wgpu::VertexState {
++                        module: &shader,
++                        entry_point: Some(vertex),
++                        compilation_options: Default::default(),
++                        buffers,
++                    },
++                    primitive: wgpu::PrimitiveState {
++                        cull_mode: Some(wgpu::Face::Back),
++                        ..Default::default()
++                    },
++                    depth_stencil: gbuffer_depth.clone(),
++                    multisample: Default::default(),
++                    fragment: Some(wgpu::FragmentState {
++                        module: &shader,
++                        entry_point: Some("fs_water"),
++                        compilation_options: wgpu::PipelineCompilationOptions {
++                            constants: &water_constants,
++                            ..Default::default()
++                        },
++                        targets: &water_targets,
++                    }),
++                    multiview_mask: None,
++                    cache: None,
++                })
++            };
++        let gbuffer_water =
++            water_pipeline(&layout, "HD water terrain", "vs_terrain", &terrain_buffers);
+         let shadow_terrain = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+             label: Some("HD shadows terrain"),
+             layout: Some(&layout),
+@@ -2597,6 +2656,7 @@ impl Renderer {
+                 &device,
+                 &bindings,
+                 arena.page_vertices(),
++                |layout, label| water_pipeline(layout, label, "vs_terrain_flat", &buffers),
+                 |layout, label, fragment, blend| {
+                     pipeline_in(
+                         layout,
+@@ -2816,6 +2876,7 @@ impl Renderer {
+             mod_post_hdr: false,
+             mod_views: None,
+             gbuffer_terrain,
++            gbuffer_water,
+             gbuffer_entity,
+             shadow_terrain,
+             shadow_entity,
+@@ -4204,6 +4265,16 @@ impl Renderer {
+             fog_color,
+             fog,
+             sky: frame.skybox && !frame.end_sky && !frame.nether_lighting && !frame.underwater,
++            sky_color: [
++                frame.sky.sky_color[0],
++                frame.sky.sky_color[1],
++                frame.sky.sky_color[2],
++            ],
++            camera_mod: [
++                camera.x.rem_euclid(256.0) as f32,
++                camera.z.rem_euclid(256.0) as f32,
++            ],
++            water: !frame.underwater,
+         };
+         let (shadow_dir, shadow_strength, _) = hd::light_of(&hd_scene);
+         let mut hd_cascades = hd::cascades(camera, shadow_dir);
+@@ -5058,6 +5129,11 @@ impl Renderer {
+                 .hd
+                 .get_or_insert_with(|| hd::Hd::new(device, size, format, globals_size));
+             hd.resize(device, size, [self.config.width, self.config.height]);
++            // Translucent terrain on screen: the water pass has something to draw.
++            hd.water_geometry = match self.flat.as_ref().filter(|_| flat_frame) {
++                Some(flat) => !flat.translucent_calls().is_empty(),
++                None => translucent_draws > 0,
++            };
+             if let Some(settings) = frame.hd {
+                 hd.write(&self.queue, &hd_scene, frame.hd_lights, settings);
+             }
+@@ -5186,6 +5262,32 @@ impl Renderer {
+             drop(pass);
+             // Contact shadows from the G-buffer's depth and normals, for the lighting.
+             hd.ao(&mut encoder);
++            // The water quads alone, with their own depth: the lighting finds the water by it and
++            // the composite after the lighting lays the surface over the lit floor.
++            if hd.water_active() {
++                let mut pass = hd.water_pass(&mut encoder);
++                pass.set_bind_group(0, &self.group, &[]);
++                match self.flat.as_ref().filter(|_| flat_frame) {
++                    Some(flat) => {
++                        pass.set_pipeline(&flat.water);
++                        flat.draw(&mut pass, flat.translucent_calls(), |p| {
++                            self.arena.buffer(p)
++                        });
++                    }
++                    None => {
++                        pass.set_pipeline(&self.gbuffer_water);
++                        pass.set_index_buffer(self.indices.slice(..), wgpu::IndexFormat::Uint32);
++                        pass.set_vertex_buffer(1, self.instances.slice(..));
++                        self.draw_sections(
++                            &mut pass,
++                            &self.indirect,
++                            0,
++                            solid_draws,
++                            translucent_draws,
++                        );
++                    }
++                }
++            }
+         } else if !hd_on {
+             self.hd = None;
+         }
+@@ -5721,6 +5823,11 @@ impl Renderer {
+                 (color, depth),
+                 (&self.lightmap_view, &self.lightmap_sampler),
+             );
++            hd.water_composite(
++                &self.device,
++                &mut encoder,
++                (&self.lightmap_view, &self.lightmap_sampler),
++            );
+             match &mut self.mod_post {
+                 Some(post) if mod_post => {
+                     let size = self.world_post.size().unwrap_or([1, 1]);
+@@ -5731,7 +5838,7 @@ impl Renderer {
+                         &self.mod_params.0,
+                         self.mod_params.1,
+                     );
+-                    post.run(&self.device, &mut encoder, (&hd.lit, depth), &hd.fx);
++                    post.run(&self.device, &mut encoder, (hd.lit_view(), depth), &hd.fx);
+                     let source = hd.taa(&self.device, &mut encoder, hd::HdSource::Fx, depth);
+                     hd.finish(&self.device, &mut encoder, source, &view_target);
+                 }
+diff --git a/crates/horizon-client/src/gfx/flat.rs b/crates/horizon-client/src/gfx/flat.rs
+index 5d86888da..7e2e20cad 100644
+--- a/crates/horizon-client/src/gfx/flat.rs
++++ b/crates/horizon-client/src/gfx/flat.rs
+@@ -64,6 +64,8 @@ pub struct Call {
+ pub struct Flat {
+     pub solid: wgpu::RenderPipeline,
+     pub translucent: wgpu::RenderPipeline,
++    /// The water quads alone, into HD's water targets.
++    pub water: wgpu::RenderPipeline,
+     flatten: wgpu::ComputePipeline,
+     compute_layout: wgpu::BindGroupLayout,
+     flatten_seen: wgpu::ComputePipeline,
+@@ -254,6 +256,7 @@ impl Flat {
+         device: &wgpu::Device,
+         terrain_layout: &wgpu::BindGroupLayout,
+         page_vertices: u64,
++        water: impl Fn(&wgpu::PipelineLayout, &str) -> wgpu::RenderPipeline,
+         pipeline: impl Fn(
+             &wgpu::PipelineLayout,
+             &str,
+@@ -320,6 +323,7 @@ impl Flat {
+                 "fs_translucent",
+                 Some(wgpu::BlendState::ALPHA_BLENDING),
+             ),
++            water: water(&layout, "HD water terrain (flat)"),
+             flatten,
+             compute_layout,
+             flatten_seen,
+diff --git a/crates/horizon-client/src/gfx/hd.rs b/crates/horizon-client/src/gfx/hd.rs
+index c54b7b961..f5caa2d0b 100644
+--- a/crates/horizon-client/src/gfx/hd.rs
++++ b/crates/horizon-client/src/gfx/hd.rs
+@@ -16,6 +16,9 @@ pub const NORMAL: wgpu::TextureFormat = wgpu::TextureFormat::Rgba16Float;
+ pub const LIGHT_LEVELS: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;
+ /// The lit world and the post pass's output.
+ pub const HDR: wgpu::TextureFormat = wgpu::TextureFormat::Rgba16Float;
++/// The water pass's targets: the surface colour with the block light, and the normal with the sky light.
++pub const WATER_TINT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba16Float;
++pub const WATER_NORMAL: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;
+ /// The most lights drawn a frame.
+ pub const MAX_LIGHTS: usize = 512;
+ /// The side (pixels) of a tile of the screen with its own short list of lights.
+@@ -91,6 +94,13 @@ struct HdFrame {
+     taa: [f32; 4],
+     /// x: the history's weight; y: the sharpening (0 without TAA); zw: the jitter in world pixels.
+     taa_params: [f32; 4],
++    /// The (jittered) world-to-clip matrix the world was drawn with (rays in the water pass).
++    view_proj: [[f32; 4]; 4],
++    /// x: the water effect runs this frame; y: seconds for the waves (wraps at 600); zw: the
++    /// camera's x and z modulo 256, the waves' period.
++    water: [f32; 4],
++    /// rgb: the sky's colour; w: 1 when there is a sky.
++    sky_color: [f32; 4],
+ }
+ 
+ /// What the world around looks like this frame (from the renderer's globals).
+@@ -116,6 +126,11 @@ pub struct HdScene {
+     pub fog: [f32; 4],
+     /// The sky has a sun at all (the Overworld).
+     pub sky: bool,
++    pub sky_color: [f32; 3],
++    /// The camera's x and z modulo 256 (the waves' period), so the waves hold still in the world.
++    pub camera_mod: [f32; 2],
++    /// The water effect may run (not underwater, not disabled).
++    pub water: bool,
+ }
+ 
+ /// The cascades' half sizes (blocks) and shadow map size.
+@@ -137,6 +152,9 @@ struct HdFrame {
+     prev_view_proj: mat4x4<f32>,
+     taa: vec4<f32>,
+     taa_params: vec4<f32>,
++    view_proj: mat4x4<f32>,
++    water: vec4<f32>,
++    sky_color: vec4<f32>,
+ }
+ struct FullOut {
+     @builtin(position) position: vec4<f32>,
+@@ -175,6 +193,8 @@ struct Light {
+ @group(0) @binding(12) var<storage, read> tiles: array<u32>;
+ // Ambient occlusion at half resolution: x the occlusion (1 open), y the distance it was taken at.
+ @group(0) @binding(13) var ao_tex: texture_2d<f32>;
++// The water pass's depth: the nearest water surface (0 where there is none).
++@group(0) @binding(14) var water_depth: texture_depth_2d;
+ 
+ // The occlusion at a full-resolution pixel `dist` away: the four nearest half-resolution texels
+ // weighted by closeness and by how near their distance is, so it doesn't bleed across edges.
+@@ -216,6 +236,12 @@ fn cascade_at(p: vec3<f32>, c: i32) -> vec3<f32> {
+ 
+ // The sun's (or moon's) light reaching p: 1 lit, 0 in shadow; soft-edged.
+ fn shadow(p: vec3<f32>, n: vec3<f32>) -> f32 {
++    return shadow_taps(p, n, 1);
++}
++
++// `shadow` with a (2 * r + 1) square of taps: the floor under water takes one (the water dims and
++// blurs it anyway).
++fn shadow_taps(p: vec3<f32>, n: vec3<f32>, r: i32) -> f32 {
+     let dist = length(p);
+     let c = select(1, 0, dist < frame.shadow.y * 0.92);
+     let texel = select(frame.shadow.z, frame.shadow.y, c == 0) * 2.0 / 2048.0;
+@@ -224,13 +250,13 @@ fn shadow(p: vec3<f32>, n: vec3<f32>) -> f32 {
+     if any(s.xy < vec2<f32>(0.0)) || any(s.xy > vec2<f32>(1.0)) || s.z > 1.0 { return 1.0; }
+     var lit = 0.0;
+     let step = 1.0 / 2048.0;
+-    for (var y = -1; y <= 1; y++) {
+-        for (var x = -1; x <= 1; x++) {
++    for (var y = -r; y <= r; y++) {
++        for (var x = -r; x <= r; x++) {
+             lit += textureSampleCompareLevel(shadow_map, shadow_sampler, s.xy + vec2<f32>(f32(x), f32(y)) * step, c, s.z - 0.0005);
+         }
+     }
+     let fade = clamp((frame.shadow.z - dist) / 16.0, 0.0, 1.0);
+-    return mix(1.0, lit / 9.0, fade);
++    return mix(1.0, lit / f32((2 * r + 1) * (2 * r + 1)), fade);
+ }
+ 
+ // One shadow sample, for the rays through the air.
+@@ -252,7 +278,15 @@ fn fs_light(in: FullOut) -> @location(0) vec4<f32> {
+     let scene = textureLoad(scene_color, px, 0).rgb;
+     let d = textureLoad(scene_depth, px, 0);
+     let g = textureLoad(gbuffer_depth, px, 0);
+-    let ndc = vec4<f32>(in.uv.x * 2.0 - 1.0, 1.0 - in.uv.y * 2.0, max(d, 0.000001), 1.0);
++    // Water in front of the opaque world with nothing translucent over it: here the floor is lit
++    // and the water composite lays the surface over it (it knows the pixel by the alpha 0.5).
++    var water = false;
++    if frame.water.x > 0.5 && g > 0.0 {
++        let wd = textureLoad(water_depth, px, 0);
++        water = wd > 0.0 && wd >= g && d - wd <= d * 0.002;
++    }
++    let dd = select(d, g, water);
++    let ndc = vec4<f32>(in.uv.x * 2.0 - 1.0, 1.0 - in.uv.y * 2.0, max(dd, 0.000001), 1.0);
+     let h = frame.inverse_view_proj * ndc;
+     let p = h.xyz / h.w;
+     let view = normalize(p);
+@@ -267,7 +301,7 @@ fn fs_light(in: FullOut) -> @location(0) vec4<f32> {
+     let halo_all = tiles[tile + 3u] == 0xffffffffu;
+     let halo_count = select(tiles[tile + 3u], count, halo_all);
+     var c = scene;
+-    let surface = d > 0.0 && abs(d - g) <= max(d, g) * 0.002;
++    let surface = water || (d > 0.0 && abs(d - g) <= max(d, g) * 0.002);
+     if surface {
+         let n = normalize(textureLoad(normal_tex, px, 0).xyz);
+         let albedo = textureLoad(albedo_tex, px, 0);
+@@ -278,14 +312,15 @@ fn fs_light(in: FullOut) -> @location(0) vec4<f32> {
+         let sky_reach = smoothstep(0.35, 0.95, lm.x);
+         var s = 1.0;
+         let ndl = dot(n, sun);
+-        if sun_on > 0.0 && ndl > 0.0 && sky_reach > 0.0 { s = shadow(p, n); } else { s = 0.0; }
++        if sun_on > 0.0 && ndl > 0.0 && sky_reach > 0.0 { s = shadow_taps(p, n, select(1, 0, water)); } else { s = 0.0; }
+         // Shadowed sky light (ambient) keeps vanilla's look, blocks' light stays as is; the sun adds
+         // direct light by the face's angle.
+         let direct = frame.sun_color.rgb * sun_on * max(ndl, 0.0) * s * sky_reach;
+         // Contact shadows from the ambient occlusion: on the ambient and blocks' light fully, on
+         // the mods' lights by half, not on the sun or on emission.
+         var occlusion = 1.0;
+-        if frame.ambient.w > 0.0 { occlusion = ao_at(px, length(p)); }
++        // (The water dims and blurs the floor under it: no occlusion there.)
++        if frame.ambient.w > 0.0 && !water { occlusion = ao_at(px, length(p)); }
+         let ao_ambient = mix(1.0, occlusion, frame.ambient.w);
+         let ao_lights = mix(1.0, occlusion, frame.ambient.w * 0.5);
+         var light = max(base * frame.ambient.x, block * frame.ambient.y) * ao_ambient + direct;
+@@ -334,7 +369,253 @@ fn fs_light(in: FullOut) -> @location(0) vec4<f32> {
+         let a1 = atan((far - t0) / hh);
+         c += l.color.rgb * l.color.w * (a1 - a0) / hh * 0.004 * (0.3 + density * 300.0);
+     }
+-    return vec4<f32>(c, 1.0);
++    return vec4<f32>(c, select(1.0, 0.5, water));
++}
++"#;
++
++const WATER: &str = r#"
++const PI: f32 = 3.14159265;
++const REFLECT_STEPS: i32 = 24;
++const REFLECT_RANGE: f32 = 96.0;
++@group(0) @binding(0) var<uniform> frame: HdFrame;
++@group(0) @binding(1) var lit_tex: texture_2d<f32>;
++@group(0) @binding(2) var gbuffer_depth: texture_depth_2d;
++@group(0) @binding(3) var water_tint: texture_2d<f32>;
++@group(0) @binding(4) var water_normal: texture_2d<f32>;
++@group(0) @binding(5) var water_depth: texture_depth_2d;
++@group(0) @binding(6) var shadow_map: texture_depth_2d_array;
++@group(0) @binding(7) var shadow_sampler: sampler_comparison;
++@group(0) @binding(8) var lightmap: texture_2d<f32>;
++@group(0) @binding(9) var linear: sampler;
++
++fn ign(px: vec2<f32>) -> f32 {
++    let p = px + vec2<f32>(5.588238 * frame.params.w);
++    return fract(52.9829189 * fract(dot(p, vec2<f32>(0.06711056, 0.00583715))));
++}
++
++// The camera-relative position of the screen point `uv` at depth z.
++fn position_at(uv: vec2<f32>, z: f32) -> vec3<f32> {
++    let h = frame.inverse_view_proj * vec4<f32>(uv.x * 2.0 - 1.0, 1.0 - uv.y * 2.0, z, 1.0);
++    return h.xyz / h.w;
++}
++
++// The screen point (uv, clip w) of a camera-relative position.
++fn project(p: vec3<f32>) -> vec3<f32> {
++    let c = frame.view_proj * vec4<f32>(p, 1.0);
++    return vec3<f32>(c.x / c.w * 0.5 + 0.5, 0.5 - c.y / c.w * 0.5, c.w);
++}
++
++fn on_screen(uv: vec2<f32>) -> bool {
++    return all(uv > vec2<f32>(0.0)) && all(uv < vec2<f32>(1.0));
++}
++
++fn texel(uv: vec2<f32>) -> vec2<i32> {
++    return clamp(vec2<i32>(uv * frame.resolution.xy), vec2<i32>(0), vec2<i32>(frame.resolution.xy) - 1);
++}
++
++// Sine waves in world space: wave vectors that are whole multiples of 2 pi / 256 and speeds that
++// are whole cycles per 600 s, so the sum repeats every 256 blocks and 10 minutes and holds still
++// in the world as the camera moves. x, y: the vector in units of 2 pi / 256; z: the slope the
++// wave adds; w: its phase.
++const WAVES = array<vec4<f32>, 10>(
++    vec4<f32>(3.0, 1.0, 0.040, 0.3),
++    vec4<f32>(-2.0, 5.0, 0.045, 2.1),
++    vec4<f32>(7.0, 2.0, 0.040, 4.4),
++    vec4<f32>(-5.0, -9.0, 0.040, 1.2),
++    vec4<f32>(11.0, -4.0, 0.035, 5.6),
++    vec4<f32>(13.0, 10.0, 0.035, 3.3),
++    vec4<f32>(-17.0, 7.0, 0.030, 0.9),
++    vec4<f32>(9.0, 23.0, 0.030, 2.7),
++    vec4<f32>(-27.0, 19.0, 0.025, 4.9),
++    vec4<f32>(31.0, 30.0, 0.025, 1.8),
++);
++
++// The gradient of the water's height at world x, z: the waves that a pixel `footprint` blocks
++// wide can still resolve (finer ones fade out, or they would shimmer).
++fn wave_gradient(xz: vec2<f32>, footprint: f32) -> vec2<f32> {
++    var grad = vec2<f32>(0.0);
++    for (var i = 0; i < 10; i++) {
++        let w = WAVES[i];
++        let k = w.xy * (2.0 * PI / 256.0);
++        let len = length(k);
++        let fade = clamp((2.0 * PI / len) / max(footprint, 0.0001) * 0.25 - 0.5, 0.0, 1.0);
++        let cycles = round(sqrt(9.8 * len) * 0.5 * 600.0 / (2.0 * PI));
++        let omega = cycles * 2.0 * PI / 600.0;
++        let phase = dot(k, xz) - omega * frame.water.y + w.w;
++        grad += (k / len) * (w.z * fade * cos(phase));
++    }
++    return grad;
++}
++
++fn cascade_at(p: vec3<f32>, c: i32) -> vec3<f32> {
++    let s = frame.cascades[c] * vec4<f32>(p, 1.0);
++    return vec3<f32>(s.x * 0.5 + 0.5, 0.5 - s.y * 0.5, s.z);
++}
++
++// The sun's (or moon's) light reaching p: 1 lit, 0 in shadow (as the lighting pass has it).
++fn shadow(p: vec3<f32>, n: vec3<f32>) -> f32 {
++    let dist = length(p);
++    let c = select(1, 0, dist < frame.shadow.y * 0.92);
++    let texel_size = select(frame.shadow.z, frame.shadow.y, c == 0) * 2.0 / 2048.0;
++    let q = p + n * texel_size * 1.5;
++    let s = cascade_at(q, c);
++    if any(s.xy < vec2<f32>(0.0)) || any(s.xy > vec2<f32>(1.0)) || s.z > 1.0 { return 1.0; }
++    var lit = 0.0;
++    let step = 1.0 / 2048.0;
++    for (var y = -1; y <= 1; y++) {
++        for (var x = -1; x <= 1; x++) {
++            lit += textureSampleCompareLevel(shadow_map, shadow_sampler, s.xy + vec2<f32>(f32(x), f32(y)) * step, c, s.z - 0.0005);
++        }
++    }
++    let fade = clamp((frame.shadow.z - dist) / 16.0, 0.0, 1.0);
++    return mix(1.0, lit / 9.0, fade);
++}
++
++fn linear_fog(d: f32, start: f32, end: f32) -> f32 {
++    if d <= start { return 0.0; }
++    if d >= end { return 1.0; }
++    return (d - start) / (end - start);
++}
++
++// What the sky shows along r when the ray leaves the screen: the horizon's colour rising to
++// the zenith's, darker where the water lies under cover (`vis` is the sky light there).
++fn sky_along(r: vec3<f32>, vis: f32) -> vec3<f32> {
++    var c = frame.fog_color.rgb;
++    if frame.sky_color.w > 0.5 {
++        c = mix(frame.fog_color.rgb, frame.sky_color.rgb, smoothstep(0.0, 0.5, r.y));
++    }
++    return c * mix(0.12, 1.0, vis);
++}
++
++// Marches the ray from p along r over the depth buffer (28 steps, growing, jittered so TAA
++// averages the placement; then a binary search for the crossing). xyz: the colour found,
++// w: how much to trust it (0 for a miss, less near the screen's edge).
++fn reflection(p: vec3<f32>, r: vec3<f32>, jitter: f32) -> vec4<f32> {
++    var near = 0.0;
++    for (var i = 0; i < REFLECT_STEPS; i++) {
++        let u = (f32(i) + jitter) / f32(REFLECT_STEPS);
++        let s = 0.12 + REFLECT_RANGE * u * u;
++        let q = p + r * s;
++        let sp = project(q);
++        if sp.z <= 0.0 || !on_screen(sp.xy) { break; }
++        let z = textureLoad(gbuffer_depth, texel(sp.xy), 0);
++        if z > 0.0 {
++            let c = frame.view_proj * vec4<f32>(q, 1.0);
++            // Reversed Z: a larger depth is nearer; the ray is behind the surface when the
++            // surface is nearer than it.
++            if z > c.z / c.w {
++                let behind = length(q) - length(position_at(sp.xy, z));
++                if behind < 0.4 + 0.08 * s {
++                    var lo = near;
++                    var hi = s;
++                    for (var k = 0; k < 5; k++) {
++                        let m = 0.5 * (lo + hi);
++                        let mq = p + r * m;
++                        let mp = project(mq);
++                        let mc = frame.view_proj * vec4<f32>(mq, 1.0);
++                        let mz = textureLoad(gbuffer_depth, texel(mp.xy), 0);
++                        if mz > mc.z / mc.w { hi = m; } else { lo = m; }
++                    }
++                    let hp = project(p + r * hi);
++                    let edge = min(min(hp.x, 1.0 - hp.x), min(hp.y, 1.0 - hp.y));
++                    let colour = textureSampleLevel(lit_tex, linear, hp.xy, 0.0).rgb;
++                    return vec4<f32>(colour, smoothstep(0.0, 0.08, edge));
++                }
++            }
++        }
++        near = s;
++    }
++    return vec4<f32>(0.0);
++}
++
++// The sun's glint on the waves (GGX, a rough lobe so it glitters instead of aliasing).
++fn glint(n: vec3<f32>, v: vec3<f32>, l: vec3<f32>) -> f32 {
++    let h = normalize(l + v);
++    let a = 0.05;
++    let nh = max(dot(n, h), 0.0);
++    let d = a * a / (PI * pow(nh * nh * (a * a - 1.0) + 1.0, 2.0));
++    let f = 0.02 + 0.98 * pow(1.0 - max(dot(v, h), 0.0), 5.0);
++    return min(d * f * 0.25 * max(dot(n, l), 0.0) / max(dot(n, v), 0.1), 12.0);
++}
++
++// The water over the lit world: the world behind it (refracted by the waves, dimmed and tinted
++// by the water's depth), the sky and the world above it (a screen-space reflection) by Fresnel,
++// and the sun's glint. Pixels without water pass through.
++@fragment
++fn fs_water(in: FullOut) -> @location(0) vec4<f32> {
++    let px = vec2<i32>(in.position.xy);
++    let base = textureLoad(lit_tex, px, 0);
++    if base.a > 0.75 { return vec4<f32>(base.rgb, 1.0); }
++    let wd = textureLoad(water_depth, px, 0);
++    let g = textureLoad(gbuffer_depth, px, 0);
++    let tint = textureLoad(water_tint, px, 0);
++    let nt = textureLoad(water_normal, px, 0);
++    let p = position_at(in.uv, wd);
++    let dist = length(p);
++    let v = -p / dist;
++    let geometric = normalize(nt.xyz * 2.0 - 1.0);
++    // The waves tilt the flat parts of the surface only.
++    let footprint = dist * frame.resolution.w * 1.4;
++    let grad = wave_gradient(p.xz + frame.water.zw, footprint);
++    let flat_part = smoothstep(0.6, 0.95, geometric.y);
++    var n = normalize(geometric + vec3<f32>(-grad.x, 0.0, -grad.y) * flat_part);
++    n = normalize(n + v * max(0.03 - dot(n, v), 0.0));
++    let ndv = max(dot(n, v), 0.02);
++
++    // Light on the water: vanilla's lightmap at the surface, and the sun where it reaches.
++    let levels = vec2<f32>(nt.a, tint.a);
++    let sky_reach = smoothstep(0.35, 0.95, levels.x);
++    let ambient = textureSampleLevel(lightmap, linear, clamp(vec2<f32>(levels.y, levels.x) * (15.0 / 16.0) + 0.5 / 16.0, vec2<f32>(0.5 / 16.0), vec2<f32>(15.5 / 16.0)), 0.0).rgb;
++    let block = textureSampleLevel(lightmap, linear, vec2<f32>(levels.y * (15.0 / 16.0) + 0.5 / 16.0, 0.5 / 16.0), 0.0).rgb;
++    let sun = frame.sun.xyz;
++    let sun_on = frame.sun.w;
++    var sunlit = 0.0;
++    if sun_on > 0.0 && sun.y > 0.0 && sky_reach > 0.0 { sunlit = shadow(p, vec3<f32>(0.0, 1.0, 0.0)) * sky_reach; }
++    let volume_light = max(ambient * frame.ambient.x, block * frame.ambient.y) + frame.sun_color.rgb * sun_on * sunlit * 0.8;
++
++    // Refraction: where the ray through the waves meets the world, against where the flat surface
++    // would send it (so still water looks as vanilla's and only the waves distort).
++    let floor0 = position_at(in.uv, g);
++    let depth0 = max(length(floor0) - dist, 0.0);
++    let bent = refract(-v, n, 0.75) - refract(-v, geometric, 0.75);
++    var uv_floor = in.uv;
++    var floor_z = g;
++    let moved = project(floor0 + bent * min(depth0, 24.0));
++    if moved.z > 0.0 && on_screen(moved.xy) {
++        let z = textureLoad(gbuffer_depth, texel(moved.xy), 0);
++        // Only what lies behind the water: not the bank or an entity in front of it.
++        if z > 0.0 && z <= wd {
++            uv_floor = moved.xy;
++            floor_z = z;
++        }
++    }
++    let thickness = clamp(length(position_at(uv_floor, floor_z)) - dist, 0.0, 48.0);
++    let behind = textureSampleLevel(lit_tex, linear, uv_floor, 0.0).rgb;
++    let colour = clamp(tint.rgb, vec3<f32>(0.03), vec3<f32>(1.0));
++    // The colours the water takes up fastest are the ones it has the least of.
++    let absorb = exp(-(vec3<f32>(1.0) - colour) * 0.8 * (thickness + 0.3));
++    let refracted = behind * absorb + colour * volume_light * 0.9 * (vec3<f32>(1.0) - absorb);
++
++    // Reflection: the screen where the ray stays on it, the sky where it leaves it or misses.
++    var r = reflect(-v, n);
++    r.y = abs(r.y);
++    // Looking down onto it the reflection is a few percent of the picture: the sky alone does.
++    let fresnel = 0.02 + 0.98 * pow(1.0 - ndv, 5.0);
++    var hit = vec4<f32>(0.0);
++    if fresnel > 0.04 { hit = reflection(p, r, ign(in.position.xy)); }
++    let sky_vis = mix(0.15, 1.0, sky_reach);
++    let reflected = mix(sky_along(r, sky_vis), hit.rgb, hit.w);
++
++    var c = refracted * (1.0 - fresnel) + reflected * fresnel;
++    if sun_on > 0.0 && sunlit > 0.0 {
++        c += frame.sun_color.rgb * sun_on * sunlit * glint(n, v, sun);
++    }
++    // Vanilla's fog over it, at the surface.
++    let sph = dist;
++    let cyl = max(length(p.xz), abs(p.y));
++    let f = max(linear_fog(sph, frame.fog.x, frame.fog.y), linear_fog(cyl, frame.fog.z, frame.fog.w));
++    c = mix(c, frame.fog_color.rgb, f * frame.fog_color.a);
++    return vec4<f32>(max(c, vec3<f32>(0.0)), 1.0);
+ }
+ "#;
+ 
+@@ -829,6 +1110,12 @@ pub fn taa_enabled() -> bool {
+     *ON.get_or_init(|| std::env::var("HORIZON_HD_TAA").map_or(true, |v| v != "0"))
+ }
+ 
++/// The water effect is on unless `HORIZON_HD_WATER=0`.
++pub fn water_enabled() -> bool {
++    static ON: std::sync::OnceLock<bool> = std::sync::OnceLock::new();
++    *ON.get_or_init(|| std::env::var("HORIZON_HD_WATER").map_or(true, |v| v != "0"))
++}
++
+ /// The Halton sequence's `index`-th number in `base`, in (0, 1).
+ fn halton(mut index: u32, base: u32) -> f32 {
+     let (mut f, mut r) = (1.0, 0.0);
+@@ -895,6 +1182,22 @@ pub struct Hd {
+     /// The lit world, and the post pass's output.
+     pub lit: wgpu::TextureView,
+     pub fx: wgpu::TextureView,
++    /// Water: its surface colour and normal, its depth (the nearest water surface; 0 elsewhere),
++    /// the lit world with the water over it, and what draws and composites them.
++    water_tint: wgpu::TextureView,
++    water_normal: wgpu::TextureView,
++    water_depth: wgpu::TextureView,
++    lit_water: wgpu::TextureView,
++    water_layout: wgpu::BindGroupLayout,
++    water_pipeline: wgpu::RenderPipeline,
++    water_group: Option<((wgpu::TextureView, wgpu::Sampler), wgpu::BindGroup)>,
++    /// The water effect runs this frame (the scene allows it and there is translucent terrain on
++    /// screen), and `lit_view` is the composite.
++    water_active: bool,
++    /// The frame's translucent terrain exists (set by the renderer before `write`).
++    pub water_geometry: bool,
++    water_composited: bool,
++    started: std::time::Instant,
+     /// TAA: the resolved frame, and the two histories (one read, one written, alternating).
+     taa: wgpu::TextureView,
+     history: [wgpu::TextureView; 2],
+@@ -1216,6 +1519,26 @@ impl Hd {
+                     min_binding_size: None,
+                 },
+                 UNFILTERED,
++                DEPTH,
++            ]),
++        });
++        let water_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
++            label: Some("HD water"),
++            entries: &entries(&[
++                UNIFORM,
++                FLOAT,
++                DEPTH,
++                UNFILTERED,
++                UNFILTERED,
++                DEPTH,
++                wgpu::BindingType::Texture {
++                    sample_type: wgpu::TextureSampleType::Depth,
++                    view_dimension: wgpu::TextureViewDimension::D2Array,
++                    multisampled: false,
++                },
++                wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Comparison),
++                FLOAT,
++                SAMPLER,
+             ]),
+         });
+         let taa_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+@@ -1278,6 +1601,16 @@ impl Hd {
+         let tone = module(device, "HD tone mapping", TONEMAP);
+         let ao = module(device, "HD ambient occlusion", AO);
+         let ao_blur = module(device, "HD ambient occlusion blur", AO_BLUR);
++        let water = module(device, "HD water", WATER);
++        let water_pipeline = fullscreen(
++            device,
++            "HD water",
++            &water_layout,
++            &water,
++            "fs_water",
++            HDR,
++            None,
++        );
+         let ao_pipeline = fullscreen(
+             device,
+             "HD ambient occlusion",
+@@ -1436,6 +1769,23 @@ impl Hd {
+             .view,
+             lit: target(device, "HD lit", [1, 1], HDR).view,
+             fx: target(device, "HD post", [1, 1], HDR).view,
++            water_tint: target(device, "HD water colour", [1, 1], WATER_TINT).view,
++            water_normal: target(device, "HD water normal", [1, 1], WATER_NORMAL).view,
++            water_depth: target(
++                device,
++                "HD water depth",
++                [1, 1],
++                wgpu::TextureFormat::Depth32Float,
++            )
++            .view,
++            lit_water: target(device, "HD lit with water", [1, 1], HDR).view,
++            water_layout,
++            water_pipeline,
++            water_group: None,
++            water_active: false,
++            water_geometry: false,
++            water_composited: false,
++            started: std::time::Instant::now(),
+             taa: target(device, "HD TAA", [1, 1], HDR).view,
+             history: [
+                 target(device, "HD TAA history", [1, 1], HDR).view,
+@@ -1502,6 +1852,17 @@ impl Hd {
+         self.depth = target(device, "HD depth", size, wgpu::TextureFormat::Depth32Float).view;
+         self.lit = target(device, "HD lit", size, HDR).view;
+         self.fx = target(device, "HD post", size, HDR).view;
++        self.water_tint = target(device, "HD water colour", size, WATER_TINT).view;
++        self.water_normal = target(device, "HD water normal", size, WATER_NORMAL).view;
++        self.water_depth = target(
++            device,
++            "HD water depth",
++            size,
++            wgpu::TextureFormat::Depth32Float,
++        )
++        .view;
++        self.lit_water = target(device, "HD lit with water", size, HDR).view;
++        self.water_group = None;
+         self.taa = target(device, "HD TAA", out, HDR).view;
+         self.history = [
+             target(device, "HD TAA history", out, HDR).view,
+@@ -1591,6 +1952,7 @@ impl Hd {
+         let (dir, strength, color) = light_of(scene);
+         let cascades = scene.cascades;
+         let night = scene.dark.clamp(0.0, 1.0);
++        self.water_active = scene.water && water_enabled() && self.water_geometry;
+         self.taa_active = scene.taa && taa_enabled();
+         // A long jump of the camera (a teleport) starts the history over.
+         if !self.taa_active || scene.camera_delta.length() > 64.0 {
+@@ -1604,6 +1966,19 @@ impl Hd {
+                 scene.camera_delta.z,
+                 if self.history_ready { 1.0 } else { 0.0 },
+             ],
++            view_proj: scene.view_proj.to_cols_array_2d(),
++            water: [
++                if self.water_active { 1.0 } else { 0.0 },
++                (self.started.elapsed().as_secs_f64() % 600.0) as f32,
++                scene.camera_mod[0],
++                scene.camera_mod[1],
++            ],
++            sky_color: [
++                scene.sky_color[0],
++                scene.sky_color[1],
++                scene.sky_color[2],
++                if scene.sky { 1.0 } else { 0.0 },
++            ],
+             taa_params: [
+                 if self.upscaling() {
+                     UPSCALE_HISTORY
+@@ -1821,6 +2196,10 @@ impl Hd {
+                         binding: 13,
+                         resource: wgpu::BindingResource::TextureView(&self.ao_blurred),
+                     },
++                    wgpu::BindGroupEntry {
++                        binding: 14,
++                        resource: wgpu::BindingResource::TextureView(&self.water_depth),
++                    },
+                 ],
+             });
+             self.light_group = Some((key, group));
+@@ -1828,6 +2207,7 @@ impl Hd {
+         let Some((_, group)) = &self.light_group else {
+             return;
+         };
++        self.water_composited = false;
+         Self::draw(
+             encoder,
+             "HD lighting",
+@@ -1894,7 +2274,7 @@ impl Hd {
+         screen: &wgpu::TextureView,
+     ) {
+         let source = match source {
+-            HdSource::Lit => self.lit.clone(),
++            HdSource::Lit => self.lit_view().clone(),
+             HdSource::Fx => self.fx.clone(),
+             HdSource::Taa => self.taa.clone(),
+         };
+@@ -1993,7 +2373,7 @@ impl Hd {
+             return source;
+         }
+         let input = match source {
+-            HdSource::Lit => self.lit.clone(),
++            HdSource::Lit => self.lit_view().clone(),
+             HdSource::Fx => self.fx.clone(),
+             HdSource::Taa => return source,
+         };
+@@ -2052,6 +2432,102 @@ impl Hd {
+         HdSource::Taa
+     }
+ 
++    /// The lit world as later passes see it: with the water over it when the effect ran.
++    pub fn lit_view(&self) -> &wgpu::TextureView {
++        if self.water_composited {
++            &self.lit_water
++        } else {
++            &self.lit
++        }
++    }
++
++    /// The water effect runs this frame (the renderer draws the water quads with `water_pass`).
++    pub fn water_active(&self) -> bool {
++        self.water_active
++    }
++
++    /// The water pass's attachments: the surface colour and normal, and the water's own depth,
++    /// all cleared. The caller draws the translucent terrain with `fs_water`.
++    pub fn water_pass<'e>(
++        &mut self,
++        encoder: &'e mut wgpu::CommandEncoder,
++    ) -> wgpu::RenderPass<'e> {
++        let clear = |view| {
++            Some(wgpu::RenderPassColorAttachment {
++                view,
++                resolve_target: None,
++                depth_slice: None,
++                ops: wgpu::Operations {
++                    load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
++                    store: wgpu::StoreOp::Store,
++                },
++            })
++        };
++        encoder
++            .begin_render_pass(&wgpu::RenderPassDescriptor {
++                label: Some("HD water"),
++                timestamp_writes: stamp(&mut self.timing, "hd water"),
++                color_attachments: &[clear(&self.water_tint), clear(&self.water_normal)],
++                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
++                    view: &self.water_depth,
++                    depth_ops: Some(wgpu::Operations {
++                        load: wgpu::LoadOp::Clear(0.0),
++                        store: wgpu::StoreOp::Store,
++                    }),
++                    stencil_ops: None,
++                }),
++                ..Default::default()
++            })
++            .forget_lifetime()
++    }
++
++    /// Lays the water over the lit world (refraction, reflection, glint) into a target of its
++    /// own; `lit_view` is that target after this.
++    pub fn water_composite(
++        &mut self,
++        device: &wgpu::Device,
++        encoder: &mut wgpu::CommandEncoder,
++        lightmap: (&wgpu::TextureView, &wgpu::Sampler),
++    ) {
++        if !self.water_active {
++            return;
++        }
++        let key = (lightmap.0.clone(), lightmap.1.clone());
++        if self.water_group.as_ref().is_none_or(|(k, _)| *k != key) {
++            let group = self.make_group(
++                device,
++                "HD water",
++                &self.water_layout,
++                &[
++                    wgpu::BindingResource::Buffer(self.frame.as_entire_buffer_binding()),
++                    wgpu::BindingResource::TextureView(&self.lit),
++                    wgpu::BindingResource::TextureView(&self.depth),
++                    wgpu::BindingResource::TextureView(&self.water_tint),
++                    wgpu::BindingResource::TextureView(&self.water_normal),
++                    wgpu::BindingResource::TextureView(&self.water_depth),
++                    wgpu::BindingResource::TextureView(&self.shadow_array),
++                    wgpu::BindingResource::Sampler(&self.shadow_sampler),
++                    wgpu::BindingResource::TextureView(lightmap.0),
++                    wgpu::BindingResource::Sampler(&self.sampler),
++                ],
++            );
++            self.water_group = Some((key, group));
++        }
++        let Some((_, group)) = &self.water_group else {
++            return;
++        };
++        Self::draw(
++            encoder,
++            "HD water composite",
++            &self.lit_water,
++            false,
++            &self.water_pipeline,
++            group,
++            stamp(&mut self.timing, "hd water composite"),
++        );
++        self.water_composited = true;
++    }
++
+     /// The ambient occlusion from the G-buffer's depth and normals: the half-resolution pass, then
+     /// its blur. Run after the G-buffer pass; nothing when the strength is 0.
+     pub fn ao(&mut self, encoder: &mut wgpu::CommandEncoder) {
+@@ -2181,6 +2657,7 @@ mod tests {
+             ("taa", TAA),
+             ("ao", AO),
+             ("ao blur", AO_BLUR),
++            ("water", WATER),
+         ] {
+             let source = format!("{COMMON}{body}");
+             let module = naga::front::wgsl::parse_str(&source).unwrap_or_else(|e| {
+diff --git a/crates/horizon-client/src/terrain.wgsl b/crates/horizon-client/src/terrain.wgsl
+index c44449cc7..0d5d2fc89 100644
+--- a/crates/horizon-client/src/terrain.wgsl
++++ b/crates/horizon-client/src/terrain.wgsl
+@@ -182,6 +182,25 @@ fn face_normal(pos: vec3<f32>) -> vec3<f32> {
+     out.light = vec4(clamp(in.lm, vec2(0.0), vec2(1.0)), 0.0, 1.0);
+     return out;
+ }
++// AirDef fork, HD water: the water quads once more, after the G-buffer, into small targets of
++// their own: the surface colour (the water sprite times the biome tint) with the block light, and
++// the face normal with the sky light. The layers are the water sprites' (gfx.rs fills them in;
++// nothing else is water: glass, ice and the rest stay as vanilla draws them).
++override WATER_STILL: u32 = 0xffffu;
++override WATER_FLOW: u32 = 0xffffu;
++struct WaterOut {
++    @location(0) tint: vec4<f32>,
++    @location(1) normal: vec4<f32>,
++}
++@fragment fn fs_water(in: TerrainOut) -> WaterOut {
++    let layer = in.layer & 0x7fffu;
++    if layer != WATER_STILL && layer != WATER_FLOW { discard; }
++    let color = sprite(in.uv, layer) * in.tint;
++    var out: WaterOut;
++    out.tint = vec4(color.rgb, clamp(in.lm.y, 0.0, 1.0));
++    out.normal = vec4(face_normal(in.pos) * 0.5 + 0.5, clamp(in.lm.x, 0.0, 1.0));
++    return out;
++}
+ // AirDef fork: the sun's shadow map — depth only, cut-out leaves leave holes.
+ @fragment fn fs_shadow(in: TerrainOut) {
+     let a = sprite(in.uv, in.layer & 0x7fffu).a;
+-- 
+2.54.0 (Apple Git-157)
+

horizon-patches/0020-HD-water-no-vanilla-texture-on-the-surface-the-biome.patch

@@ -0,0 +1,54 @@
+From dbc6f8a6e9c2eeabe1de15f1794013c90be7faa5 Mon Sep 17 00:00:00 2001
+From: chexit <chexit@duck.com>
+Date: Thu, 29 Oct 2026 17:56:04 +0300
+Subject: [PATCH 20/20] HD water: no vanilla texture on the surface (the biome
+ colour only), a darker, deeper colour
+
+Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
+---
+ crates/horizon-client/src/gfx/hd.rs    | 9 ++++++---
+ crates/horizon-client/src/terrain.wgsl | 6 ++++--
+ 2 files changed, 10 insertions(+), 5 deletions(-)
+
+diff --git a/crates/horizon-client/src/gfx/hd.rs b/crates/horizon-client/src/gfx/hd.rs
+index f5caa2d0b..8070aab3c 100644
+--- a/crates/horizon-client/src/gfx/hd.rs
++++ b/crates/horizon-client/src/gfx/hd.rs
+@@ -591,10 +591,13 @@ fn fs_water(in: FullOut) -> @location(0) vec4<f32> {
+     }
+     let thickness = clamp(length(position_at(uv_floor, floor_z)) - dist, 0.0, 48.0);
+     let behind = textureSampleLevel(lit_tex, linear, uv_floor, 0.0).rgb;
+-    let colour = clamp(tint.rgb, vec3<f32>(0.03), vec3<f32>(1.0));
++    // A deep, dark water: the biome's colour darkened and a little greyed, so it reads as
++    // depth rather than as bright paint.
++    let biome = clamp(tint.rgb, vec3<f32>(0.03), vec3<f32>(1.0));
++    let colour = mix(vec3<f32>(dot(biome, vec3<f32>(0.333))), biome, 0.8) * vec3<f32>(0.55, 0.68, 0.8);
+     // The colours the water takes up fastest are the ones it has the least of.
+-    let absorb = exp(-(vec3<f32>(1.0) - colour) * 0.8 * (thickness + 0.3));
+-    let refracted = behind * absorb + colour * volume_light * 0.9 * (vec3<f32>(1.0) - absorb);
++    let absorb = exp(-(vec3<f32>(1.0) - colour) * 1.1 * (thickness + 0.3));
++    let refracted = behind * absorb + colour * volume_light * 0.6 * (vec3<f32>(1.0) - absorb);
+ 
+     // Reflection: the screen where the ray stays on it, the sky where it leaves it or misses.
+     var r = reflect(-v, n);
+diff --git a/crates/horizon-client/src/terrain.wgsl b/crates/horizon-client/src/terrain.wgsl
+index 0d5d2fc89..e892d5a0f 100644
+--- a/crates/horizon-client/src/terrain.wgsl
++++ b/crates/horizon-client/src/terrain.wgsl
+@@ -195,9 +195,11 @@ struct WaterOut {
+ @fragment fn fs_water(in: TerrainOut) -> WaterOut {
+     let layer = in.layer & 0x7fffu;
+     if layer != WATER_STILL && layer != WATER_FLOW { discard; }
+-    let color = sprite(in.uv, layer) * in.tint;
++    // The biome's colour at the texture's mean brightness, not the texture: the HD water draws
++    // its own surface (waves, reflections), and vanilla's ripples on top would look painted on.
++    let color = vec3(0.62) * in.tint.rgb;
+     var out: WaterOut;
+-    out.tint = vec4(color.rgb, clamp(in.lm.y, 0.0, 1.0));
++    out.tint = vec4(color, clamp(in.lm.y, 0.0, 1.0));
+     out.normal = vec4(face_normal(in.pos) * 0.5 + 0.5, clamp(in.lm.x, 0.0, 1.0));
+     return out;
+ }
+-- 
+2.54.0 (Apple Git-157)
+