Menu screens: rock background, centred frame, logo, 3D hero

- Spielen hero panel shows the selected hero in 3D (cUI_NetGranny,
  game/ui/granny.h).
- All menu screens draw on the options' rock wall; the main menu's 1024
  frame is drawn centred over it, mouse and cursor shifted to match.
- The main menu's and options' own pictures and the main menu's 3D scene
  are left out (textures hidden by surface, scene call redirected).
- Logo top left: FX_SACREDLOGO.TGA, drawn added.
- Game textures by name (game/ui/texture.h), textured and added quads.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/screens.md

@@ -2,8 +2,12 @@
 
 Request (2026-10-20): the game's menu screens are laid out for 1024x768; we
 design our own UIs for them. There is no 16:9 artwork for the game, so the
-background is our own (option 3 of the ones discussed: dark, no picture), and
-the approach is shared by all menu screens. Target: 16:9, 1920x1080, which is
+background is our own, and the approach is shared by all menu screens. The
+background (user, 2026-10-20: "textured dark", the flat gradient looked
+black): the options window's rock wall, `GUI_OPTION_BACKGROUND<row><column>.TGA`
+(4 x 3 tiles of 256), scaled to cover the render target, tinted down,
+shaded towards the bottom and the sides. Game textures by name:
+`game/ui/texture.h`, drawn with `game::DrawTextured` (game/ui/draw.h). Target: 16:9, 1920x1080, which is
 1365x768 in UI units; wider screens only get more background at the sides
 (not designed for ultrawide).
 
@@ -16,9 +20,7 @@ the approach is shared by all menu screens. Target: 16:9, 1920x1080, which is
   layer's offset machinery with `Anchor::Canvas`; drawing, the cursor and the
   window's hit tests shifted alike). Mouse events go through `screen::Handle`
   (`hud::HandleCanvas`). Keys stay the window's.
-- In the main menu the game renders a classic 1024x768 frame (presented 4:3).
-  While a screen's window is shown, `widescreen::SetWideMenuScreen` makes the
-  menu thread render and present the full width.
+- The main menu thread renders the full width (no 4:3 frame any more).
 - Parts: `screen::Panel` (dark backdrop and the game's frame, `cUI_Frame`,
   game/ui/frame.h, made anew when its rect changes), `screen::Button` (a
   button of the game's with the look of one of the window's,
@@ -33,6 +35,42 @@ the approach is shared by all menu screens. Target: 16:9, 1920x1080, which is
 - Inside the canvas scope the HUD layer does not stretch "full 1024 layout"
   quads (`g_canvasScope`).
 
+## Main menu frame (2026-10-20)
+
+Request: the background on all screens, the main menu's and the options
+window's own pictures removed.
+
+- cUI_Manager's UI render (`0x7587b0`, hooked in mods/screen.cpp) on the
+  menu thread: the background first, then `hud::RenderMenuFrame` runs the
+  render with drawing shifted by (render width - 1024) / 2 and a viewport on
+  the frame (3D parts). Windows inside draw in frame coordinates (their own
+  HUD scopes are nested, so they do nothing).
+- Mouse positions are given to the game in frame coordinates: the
+  borderless mod's `ToGame` subtracts `hud::MenuFrameOffsetX`. The cursor
+  sprite (`cMouseCursor::DrawItem` 0x6555e0, drawn after the UI) is shifted
+  by drawing only.
+- While a 16:9 screen is shown the frame is not shifted (offset 0): the
+  screen draws itself across the width.
+- Full-screen windows in a game (options, `hud::RenderFramed`) get the
+  background beside the frame instead of black.
+- The windows' pictures are left out by texture: the HUD layer tracks the
+  texture bound to stage 0 (`SetTexture`, device vtable 35) and skips quads
+  drawn with a hidden one (`hud::SetHiddenTextures`). Logged on the menu
+  thread (texture ids requested from the cache, by caller; names by trying
+  the names in the texture pak): main menu GUI_UW_OPTION1..12 + UI_MAIN_SKY,
+  options UW_OPTION_1_01..12. This install uses the Underworld versions; the
+  Ancaria ones (GUI_OPTION1..12, ...) were not seen and are not listed.
+- The main menu's 3D scene (sky UI_UW_MAIN_CENTER, water with the SACRED
+  logo UI_MAIN_REF; render 0x75e620 on the scene object 0x75df10) is called
+  from cUI_MainMenu::Render (0x7122c0) at 0x712bd9; that call is redirected
+  to an empty function. cUI_Character (0x70f41b) still draws it.
+- Logo top left (2026-10-21), 48 from the edges, 124 high: FX_SACREDLOGO.TGA,
+  the emblem (horns around a ring of runes) glowing blue on black without
+  alpha, drawn added (blend ONE/ONE, `game::DrawTexturedAdded`) as the
+  game's effects draw it. Other candidates: GUI_MAIN_LOGO (plain golden
+  lettering), SACREDSYMBOL01/02 (model atlases), the emblem on the loading
+  pictures (PAK\loading*.bmp, not in the paks). Screens may overlap it.
+
 ## Screens
 
 - Spielen (the load window, cUI_Savegame): docs/characters.md, "Spielen