# HUD layout in widened views (`src/mods/hud.cpp`)

The UI is laid out for 1024x768. In a widened render target (e.g. 1835x768)
the windows are moved as a whole, without touching their own coordinates:
the bottom bar and all dialogs are centred, the party panel (portrait, health)
sits at the right edge. Main menu and loading screen keep the classic 1024x768
frame (see `widescreen.md`).

## How a window is moved

A window's render and event methods are hooked (`HUD_RENDER`, `HUD_RENDER3`,
`HUD_EVENT`). While one of them runs on a thread, everything the window sees or
draws is translated by its offset `dx` (outermost window wins, children and
shared base methods are inside the scope):

| What | Where | Translation |
|---|---|---|
| screen-space vertices (`XYZRHW`) | `IDirect3DDevice7::DrawPrimitive` / `DrawIndexedPrimitive` (vtable 25 / 26) | x + dx |
| 3D items (belt, equipment) | ortho projection centred on the screen | none needed |
| mouse events | `cEvent_mouseMove` x at +4 (previous) and +0xc; button down / up x at +8 | x - dx, restored afterwards |
| mouse cursor object (`*0xcdbadc`, accessor `0x6550f0`) | x at +4, previous x at +0xc (polled for hover, item pick-up `0x6559a0`) | the accessor returns a per-thread copy with x - dx; dwords the window changed are written back afterwards |
| `GetMouseClientPos` (`0x66e500`) | polled position | x - dx |

## Calls outside a window's scope

- Tooltips (`cUI_Tooltip::vf14` `0x6e7300`) are separate windows that the
  hovered window positions in its own layout: they draw with the offset of the
  moved window under the cursor (noted while windows render, expires after
  150 ms).
- Hit tests (`vf1c`: `0x731d40`, taskbar `0x6dfb10`) are also called by the UI
  manager with plain render coordinates, e.g. "is UI under the cursor" for
  world picking (`0x75a370`). They use the offset the top-level window (parent
  chain at +0x50) was last drawn with.
- The item carried by the cursor (`0x6555e0`, drawn by the render loop) and the
  manager's status line / message box (`0x75bbf0`, `0x75c200`, laid out around
  x = 512) draw with the centre offset.

## UI events

`vf04` of an event is its category: 1 mouse move, 2 button down, 3 button up,
4 key (code at +8), 5 UI command (`cEventUI2`: id at +4, vf08 subtype). Only
mouse events carry positions; category 5 events with subtype 0x10 test a point
at +0x48 in `cUI_Window2::vf10`, but commands such as "open ESC menu" (0x11)
keep unrelated data there.

## Why the cursor is copied, not shifted

UI windows render on the render thread while world input (picking,
hold-to-move, `0x611f10`) reads the same cursor object on another thread.
Shifting the shared object for the duration of a window's scope let the world
sample a position ~400 px off now and then (jerky hold-to-move). Every user of
the cursor goes through the accessor `0x6550f0`, so inside a moved window it
returns a thread-local copy instead (with its own CRITICAL_SECTION at +0x24;
copying and writing back hold the real object's lock).

## Full-screen layers

A primitive drawn inside a moved window that covers the whole 1024x768 layout
(e.g. the dimming behind the exit confirmation) is stretched across the render
width instead of shifted.

## Standalone controls (quest dialog)

Some dialogs (e.g. accepting a quest) are not one of the hooked window
classes: their buttons and texts sit directly in the UI manager as top-level
controls (measured: the clicked button's root window was the cUI_Button2
itself). They were drawn unshifted or with whichever window's scope happened
to be active, so the dialog jumped between the 1024 layout and the centre and
clicks only hit at the unshifted position. `cUI_Button2`, `cUI_Static2`,
`cUI_StaticText64`, `cUI_StaticText64FX` (render and event) and
`cUI_TextLines` (render) are hooked as centred windows too; inside other
windows they are in that window's scope already (outermost wins).