---
id: glass-cockpit
title: "Glass Cockpit — the desktop developer layer (BT_GLASS / BT_STEAM)"
status: living
source_sections: "plan 2026-07-17; CMakeLists.txt gates; BT412 prior art (reference only)"
related_topics: [pod-hardware, build-and-run, multiplayer, gauges-hud]
key_terms: [PadRIO, miniconsole, glass-cockpit]
open_questions: []
---
# Glass Cockpit — the desktop developer layer

**Purpose:** developer tooling so game developers can test their work WITHOUT booting a Tesla II
pod — and stay far enough out of the game that nothing a real pod requires can break. NOT a
consumer product (GDI-grade UI is the ceiling). Pod fidelity outranks desktop convenience in
every trade-off.

## The compile gates (the ONLY compile-time feature gates in the tree)

| Gate | Default | Adds |
|---|---|---|
| `BT_GLASS` | OFF | PadRIO input (XInput+keyboard), per-display cockpit windows (or the legacy single button panel), desktop plasma window, `glass` platform preset, miniconsole mission launcher |
| `BT_STEAM` | OFF (requires `BT_GLASS`) | Steam transport (`ISteamNetworkingSockets`) + `ISteamMatchmaking` lobby |

- A **no-flags configure is the pure pod game** — the build of record. `cmake` options are
  cached, so a developer configures a `build/` with `-DBT_GLASS=ON` once.
- Build dirs: `build-pod/` (defaults, purity), `build/` (dev, glass ON), `build-steam/` (ON/ON).
- **Convention:** `BT_GLASS`/`BT_STEAM` are compile gates; every other `BT_*` name is a RUNTIME
  env gate (`BTEnvOn`) — do not add compile gates without updating this file.
- No weak-linkage/optional symbols — `/FORCE` turns unresolved externals into runtime AVs
  ([[reconstruction-gotchas]]); gated calls must be structurally present-or-absent at compile time.

## Plan of record (2026-07-17)

Working branch `glass-cockpit` (from master `e2c21c4`). Steps: (1) gates+scaffolding [THIS],
(2) PadRIO glass cockpit, (3) miniconsole self-launch, (4) Steam transport+lobby. Full plan:
the approved plan file; running detail: `docs/GLASS_COCKPIT.md`. The retired BT412 trees
(`C:\VWE\BT412`; local branch `local-abandoned-20260717`) are read-only reference — no code is
copied from them.

## Status

- **Step 1 (gates + scaffolding): DONE 2026-07-17.** CMake options + defines; 3-config
  configure matrix + negative test + defaults build verified.
- **Step 2a (.CTL id audit): DONE 2026-07-17 [T2].** The streamed `.CTL` positional ids landed
  every `MechControlsMapper` record ONE MEMBER LATE (our chain starts at 2, the binary's at 3)
  — a latent REAL-POD bug (RIO throttle would drive pedalsPosition), masked on dev boxes by the
  keyboard bridge. Fixed ungated: ids pinned to binary numbering + id-2 pad + static_assert
  locks (`mechmppr.hpp/.cpp`); torso/weapon chains were already aligned. Permanent env-gated
  diagnostic: `BT_CTRLMAP_LOG=1` dumps every streamed record's resolved member offset
  (`L4CTRL.cpp CreateStreamedMappings`). Full evidence: `docs/GLASS_COCKPIT.md` §2a.
- **Step 2 (PadRIO glass cockpit): DONE 2026-07-17 [T2].** `RIOBase` seam (`L4RIO.h`,
  unconditional) + gated `L4CONTROLS=PAD` → `PadRIO` (`L4PADRIO.*` XInput+keyboard,
  `L4PADBINDINGS.*` `content\bindings.txt`); bridge stand-downs auto-yield to a live device
  (`BTRIODevicePresent`, `BT_KEY_BRIDGE` unset=auto/0=off/1=on); on-screen panel `L4PADPANEL.*`
  follows **vRIO** (`C:\VWE\vrio` CockpitLayout/PanelCanvas — 104 controls incl. the two hex
  keypads → real KeyEvents; right-click latch); desktop plasma `L4PLASMAWIN.*`
  (`L4PLASMA=SCREEN`, buffer is top-down); `-platform glass` preset + run.cmd token. Secondary
  displays reuse the EXISTING dev-gauge modes (dock / `BT_DEV_GAUGES_WINDOW=1` window /
  `_DOCK=1` overlay — [[gauges-hud]]); no new MFD code, no `L4VB16.cpp` exposure.
  **Button-trap guard:** base `ConfigureMappableMessageHandler` no longer `abort()`s by default
  (`BT_BUTTON_TRAP=1` restores) — each `[FAIL]` log = a missing L4 override to reconstruct.
  Verified: authentic-path input (engine push → streamed `.CTL` → mapper), panel-click
  survival, 2-node loopback MP un-regressed on the pod build. Detail: `docs/GLASS_COCKPIT.md`.
- **Step 3 (miniconsole): DONE 2026-07-17 [T2].** `game/glass/btl4fe.*` (menu + console-shape
  egg writer, golden-tested vs MP.EGG) + `btl4console.*` (the marshal: a worker-thread console
  CLIENT speaking the btconsole.py wire verbatim; `content\marshal.log`). ZERO engine hooks —
  the engine runs the stock console ladder. Per-mission process relaunch; `BT_FE_*` env arms the
  marshal (menu relaunches clear it). Verified: solo cycle (menu→mission→60s clock→stop→menu)
  and menu-hosted 2-node LAN.
- **Step 4 (Steam): CODE COMPLETE 2026-07-18 [T2 single-machine].** See [[steam-networking]] —
  the wire seam + `L4STEAMNET` identity-token transport + `btl4lobby`. Live 2-account
  cross-machine session pending (`docs/STEAM_TEST.md`).
- **Input-coverage audit + keyboard reconciliation: DONE 2026-07-20 [T2].** Root cause of the
  dead panel: `MechRIOMapper`'s message ids were chained one enum too high (0x19-0x2a) — the
  binary RIO table @0051dd30 re-registers the BASE aux/zoom ids 3..0x13 (Hotbox 0x1a); fixed
  ungated + static_assert-locked (`btl4mppr.hpp`) → all 24 MFD-bank + 2 zoom buttons live
  (52/72 panel buttons now work; 8 dead await handler reconstruction — Gitea backlog issue;
  12 have no streamed mapping authored, authentically inert). **Keyboard = the ~20 core
  gameplay actions on the CONTROLS.MAP keys; the PANEL covers every pod address by click**
  (right-click = hold latch) — the merged default profile lives in `L4PADBINDINGS.cpp`
  (auto-writes `content\bindings.txt`; W/S/A/D/Q/E/R/F/X drive, 1-4/Space/Ctrl fire, M/N/H/C =
  pod buttons 0x18/0x15/0x2C/0x2F, `/V view toggle + J/K/L preset cycles hardcoded in PadRIO).
  Bound keys are SUPPRESSED from the typed 1995 channel (`PadRIO::SuppressKey`, the btinput
  pattern — ended the glass double-dispatch: 'w'=pilot-select, numpad/F-key key-up aliases);
  unbound keys keep their authentic meanings (5/z presets, t-o pilot select, +/- zoom).
  In BAS control mode the pod turns with the STICK (Q/E) and pedals are inactive — authentic;
  A/D turn in MID/ADV. Arrow keys mirror the drive cluster (UP/DOWN = the W/S throttle lever,
  LEFT/RIGHT = the A/D pedals). Full audit + census: `docs/GLASS_COCKPIT.md` §2026-07-20.
- **2026-07-20 live "keymap regression" report: STALE EXE [T2].** The human-reported glass
  regressions (arrows/lever/detent dead, V/J/K/L/N inert, ground-fire) were a
  `build-glass/Release/btl4.exe` built BEFORE 5dd3536 landed — relaunched without rebuilding.
  No input-code change was needed; a clean rebuild + full SendInput re-verification (lever
  holds + zero stop, MID turns, V toggle shot-pair, level boresight, pod smoke) closed every
  symptom, and V's edge is now [T2]. `BT_MPPR_TRACE` now prints mode/pedals/stick/turn/elev.
  Procedural rule: rebuild every live build dir after landing an input/engine commit.
  Detail: `docs/GLASS_COCKPIT.md` §2026-07-20 (later).
- **2026-07-20 human re-test: GAIT DETENT ported to the PadRIO lever [T2].** The remaining
  "our detent is missing" (mixed walk/run mode + repeated accel sample) was the gait DEAD BAND
  ([[locomotion]]): the pod-build keyboard lever snaps out of the walk/run hysteresis band at
  key-rest (mech4.cpp GAIT DETENT), and the PadRIO throttle slew lacked it. Ported faithfully:
  mech4.cpp publishes the band in lever units (`gBTGaitDetentLo/Hi` seam, +0.002 engage
  margin), `L4PADRIO.cpp` applies the identical nearer-edge snap when no throttle slew key/pad
  axis is active. Verified: parks at 0.414/0.465 snap to 0.358/0.504 (band = demand
  22.02-30.87), no at-rest sample in-band, exactly ONE up-shift + ONE down-shift clip across a
  full graduated sweep, zero-stop + pod build unaffected. Detail: `docs/GLASS_COCKPIT.md`
  §2026-07-20 (later still).
  A/D turn in MID/ADV. Full audit + census: `docs/GLASS_COCKPIT.md` §2026-07-20.
- **Per-display cockpit windows (`BT_GLASS_PANELS`): DONE 2026-07-20 [T2 startup-verified].**
  The `-platform glass` preset now breaks the secondary displays out of the single combined
  panel/strip into ONE desktop window PER pod display, each carrying that display's surface
  WITH its RIO button bank placed around it, arranged pod-faithfully around the main view
  (`engine/MUNGA_L4/L4GLASSWIN.*`, new TU). Windows: **Heat (UL) / Mfd2 (UC) / Comm (UR) /
  Mfd1 (LL) / Mfd3 (LR)** each with 8 RED MFD buttons split 4 above / 4 below the surface;
  **Secondary/Radar** (portrait `sec`) with the 12 YELLOW Secondary buttons split left/right;
  a **Flight Controls** window for the no-display banks (throttle 0x38-3F, joystick/fire
  0x40-47, panic). Each window is a GDI window (like [[gauges-hud]]'s pad panel + the plasma
  window) — the surface is CPU-expanded from the shared gauge buffer
  (`SVGA16::ExpandPlaneToBGRA`, no D3D) and `StretchDIBits`'d in, so the **whole D3D
  dev-composite path (dock / separate window / overlay) stands down** while these are up
  (`BTDrawGaugeInset`/`BTGaugeWindowRenderAndPresent` early-return; no `gBTGaugeDockBottom`
  strip). Runtime gate **`BT_GLASS_PANELS`** (default ON under `-platform glass`, `=0` falls
  back to the single pad panel + docked gauges) — read by `L4PADRIO` (which panel to create),
  `L4VB16` (suppress compositing), and `btl4main` (skip the world-window dock strip). The
  display↔bank map (spine of the feature): Heat 0x28-2F, Mfd2 0x20-27, Comm 0x30-37,
  Mfd1 0x08-0F, Mfd3 0x00-07, sec 0x10-1B ([[pod-hardware]] §Bank→MFD). Verified: build +
  bounded glass launch — `[glasswin] per-display cockpit up (7 windows…)`, no crash, full
  mission loop un-regressed; surfaces carry LIVE gauge content (`BT_GLASS_LOG` = per-surface
  resolve/pixel diagnostic). Layout constants (surface sizes, exact button sub-positions,
  yellow left/right split) are marked tunable in `L4GLASSWIN.cpp`. Detail: `docs/GLASS_COCKPIT.md`.
  ⚠ **Bug found + fixed during bring-up:** surfaces were blank because `application`/`ghWnd` are
  duplicate-defined globals that bind non-deterministically under `/FORCE` — the fresh
  `L4GLASSWIN` TU read `application == NULL` → gauge renderer NULL. Fix: reach the
  renderer/window via `BTResolveGaugeRenderer()`/`BTResolveMainWindow()`, DEFINED in
  `game/btl4main.cpp` off its real `btl4App`/`hWnd` pointers (never the globals directly). See
  [[reconstruction-gotchas]] §6 duplicate-GLOBAL corollary.

- **Glass per-display panel button click-crash (Gitea #18): FIXED 2026-07-20 [T2].** Clicking a
  per-display Engineering panel button (0x21 reported) on an **Eng page** hard-crashed — cdb: a
  wild call through an uninitialised pointer (`eip=cdcdcdcd` debug / `0x01048748` release) with
  **zero btl4 frames above `Receiver::Receive`**. Root cause was NOT a `/FORCE` unresolved
  external (the glass link log carried only the known-benign `mech3.obj` `CreateStreamedSubsystem`
  set) but a **dense message-handler-table GAP slot** ([[reconstruction-gotchas]] §11): the
  streamed Eng-page `.CTL` dispatches subsystem msg **id 3 / 0xb** to whatever subsystem is shown,
  and a **weapon (Emitter)** registers only PoweredSubsystem 4-8 + MechWeapon 9-10 — so id 3 is a
  gap below `entryCount`, and `Receiver::MessageHandlerSet::Build`'s `new HandlerEntry[]` left it
  as heap garbage → `(this->*garbage)(msg)`. The 1995 binary has the identical non-zeroing
  `new[]` and survived only on fresh-heap-zero luck (id 3 on a weapon was always meant to be
  IGNORED — it's a Condenser/Reservoir action in a different subsystem branch; the uniform
  Eng-page button template makes buttons for unimplemented actions authentically inert). The new
  per-display windows just made the id reachable live. **Fix (engine, class-wide, faithful):**
  `Build` null-inits every slot (`entryID=0/entryName=""/entryHandler=NullHandler`) before
  copying inherited / placing supplied, so a gap is deterministically NullHandler → `Receive`
  drops it — the authentic "Receiver ignores unhandled messages", not a glass-path guard. Fixes
  the entire dead-button class (#14) at once. Verified: click-soaked every MFD bank
  (Engineering/L+R Weapons/Heat/Comm, ~130 clicks through Quad↔Eng page cycles) under cdb — ZERO
  AVs, and the reconstructed mapper preset selects still fire (`[mode] preset (1,1)/(2,1)…`); pod
  build + solo un-regressed. The `[glasswin] CLICK` forensics log (names the button before
  dispatch) landed with this. Detail: `engine/MUNGA/RECEIVER.cpp` Build.

## Key Relationships
- Extends: [[pod-hardware]] (RIO input path) · Uses: [[gauges-hud]] dev-gauge modes ·
  Feeds: [[multiplayer]] (miniconsole hosting, Steam transport) · Build: [[build-and-run]]