Joe DiPrimaandClaude Opus 5
c32d02b3cc
Playtest night 5: "heat damage @ launch is lit up like a Christmas tree",
confirmed by two players at ANY spawn -- so not the respawn-reset bug it was
first filed as. Two stacked causes, both fixed here.
1. THE RATIO WAS NEVER RECONSTRUCTED. HeatConnection::Transfer @004c3720 sets
the colour index a ColorMapper pushes into the palette slot. The port wrote
*currentColorIndex = HeatRound(heat->currentTemperature);
straight into an index whose range is 0..99. A stone-cold mech sits at ~77
and the generators idle near 260, so every one of the 24 cmHeat mappers in
GAUGE/L4GAUGE.CFG (GeneratorA-D, Condenser1-6, HUD, Avionics, Gyroscope,
Torso, GAUSS, the lasers, SRM6, Myomers) saturated at the hot end from the
first frame and stayed there.
The real computation was INVISIBLE in the decomp. Ghidra renders the tail as
`uVar1 = FUN_004dcd94();` -- an arg-less __ftol, exactly the carve artifact
reconstruction-gotchas §19 documents: the x87 expression that left the value
in ST0 is dropped from the export. The previous author reconstructed the
only thing visible and flagged the scaling as unreconciled in a comment.
Raw disasm @0x4c379a-0x4c37c1 recovers it:
fld [num] ; fdiv [den] ; ratio
fcomp 1.0f ; jbe -> ratio=1 ; clamp
fmul 99.0f ; call __ftol ; -> 0..99
i.e. "how close to failure am I", not a raw temperature. At spawn that is
77/2000 -> 4, and the schematic reads cold.
The two operands come from one of two branches, chosen by a class flag at
+0x14 that the port did not model at all (ctor disasm @0x4c3682-0x4c36c2):
HeatableSubsystem (0x50e3ec) -> own temp@0x114 / own failureTemperature@0x11C
HeatWatcher (0x50e604) -> WATCHED subsystem's temp@0x114
/ the WATCHER's failureTemperature@0x124
neither -> source NULLed, Transfer writes 100
Note the watcher asymmetry: temperature from the watched subsystem, reference
from the watcher itself. Bridged as BTHeatWatcherSample so the gauge TU need
not include the heat family's headers.
2. THE WATCHER BRANCH COULD NEVER BE SELECTED. With (1) fixed, HUD, Gyroscope
and Torso still pinned at 99 reading temp=1.6369e-35 failAt=0 -- uninitialised
bytes. HeatWatcher's C++ base had been re-based to MechSubsystem, but its
DERIVATION chain still said HeatableSubsystem, so every watcher answered "yes,
I am heat-bearing", took branch one, and read its own watchedLink@0x114 as a
temperature. This is the last surviving instance of the #47 bug -- in the
file that fix's own comment cites as already correct. The two families are
disjoint in the binary and the branch test depends on it.
VERIFIED LIVE (solo, F6 to the Heat schematic, BT_HEATGAUGE_LOG=1): mode mask
reached 0x510421 (ModeSecondaryHeat) and the gauge tracks per subsystem rather
than saturating -- GeneratorA 259.5->13, Condenser3 202.0->10, SRM6 182.8->9,
lasers 90-97->4-5, and AmmoBinSRM6_1 (a watcher) resolves its link and reads
182.7->9 through the branch that previously read 1.6369e-35. Nothing pinned at
99. Operator confirms the panel is blue, not red.
BT_HEATGAUGE_LOG kept as a permanent env-gated diagnostic: bind-time
classification plus per-sample temp/failAt/ratio/index. A fresh spawn reading
99 is this regression returning.
Not covered: ColorMapperCritical (cmCrit / ModeSecondaryCritical) already
computes a proper damageLevel*100 ratio and was read, not measured -- if the
Critical page specifically still misbehaves that is a separate lead.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
BattleTech 4.11 (bt411)
A standalone Windows port of Virtual World Entertainment's arcade BattleTech (Tesla platform, release 4.10, ~1995–96), reconstructed on the shared RP411 Windows engine. The game boots, renders, and runs a single-player drive → animate → target → fire → damage → destroy loop across all 8 maps, with two-instance multiplayer entity replication working.
This repo is a clean, self-contained extraction of the BattleTech-specific work from the larger reverse-engineering workspace — engine + game + content + build, with nothing from Red Planet or the raw archive dumps. It builds and runs out of the box.
License: the game content (
content/) and the original binary are proprietary to Virtual World / the pod owner. This repository is private; do not redistribute.
Versioning
4.10 = the 1995 arcade release. 4.11 = this win32 reconstruction. Dev builds are
4.11.<build> where <build> is the git commit count — monotonic and zero-maintenance —
plus the short commit hash (4.11.311 (980c9cd)); a trailing + on the hash means the exe was
built from an uncommitted working tree. The stamp regenerates every build
(tools/btversion.cmake → build/btversion.h) and shows in the boot banner (btl4.log line 2)
and the window title. To identify any player's build, ask for the title bar or the top of their
btl4.log.
Layout
CMakeLists.txt one build: munga_engine lib + bt410_l4 game lib + btl4.exe
engine/
MUNGA/ shared 2007 sim/render engine (149 .cpp + headers)
MUNGA_L4/ Win32/D3D9 HAL + renderer + asset loaders (44 .cpp), incl.
our BT work: bgfload / L4D3D / L4VIDEO + the image codec
shim/ minimal ATL shim (USES_CONVERSION/W2A)
lib/ OpenAL32 / libsndfile import libs + runtime DLLs
game/
reconstructed/ the reconstructed BT game logic (mech, subsystems, HUD, app; ~47 .cpp)
original/BT,BT_L4 surviving original BT source + all BT headers
fwd/ header shims forwarding <NAME.hpp> -> the engine's NAME.h
btl4main.cpp WinMain launcher / entry point
content/ runtime data: BTL4.RES, VIDEO/, GAUGE/, AUDIO/, *.EGG, BTDPL.INI
context/ progressive knowledge graph — 18 on-demand topic files (routed by CLAUDE.md)
docs/ format specs + reconstruction ledgers + PROGRESS_LOG.md (full history)
reference/
decomp/ raw Ghidra pseudocode — source-of-truth for ongoing recon
ghidra_scripts/ the headless decomp exporter
glossary.yaml term / acronym definitions
phases/ restructuring / investigation logs
tools/ btconsole.py (MP console emulator), map/resource scanners
run/ run.cmd helper
CLAUDE.md knowledge-base ROUTER — identity, protocols, quick-lookup, conventions
Prerequisites
- Visual Studio 2019 BuildTools (MSVC v142, x86). The Community install on the original dev box was broken, hence the explicit BuildTools instance in the configure line below; adjust to your install.
- CMake ≥ 3.20.
- Legacy DirectX SDK (June 2010) — the engine uses
d3dx9/dinput/dxerr, removed from the modern Windows SDK. Default pathC:/Program Files (x86)/Microsoft DirectX SDK (June 2010); override with-DDXSDK=<path>. (The installer may throw a harmless S1023 error — dismiss it; the SDK headers/libs install before the failing redist step.)
OpenAL/libsndfile import libs + DLLs are vendored under engine/lib/; the DLLs are copied next to
the exe automatically at build time.
Build (32-bit / Win32)
cmake -S . -B build -G "Visual Studio 16 2019" -A Win32 ^
-DCMAKE_GENERATOR_INSTANCE="C:/Program Files (x86)/Microsoft Visual Studio/2019/BuildTools"
cmake --build build --config Debug
Must be Win32 — the DirectX SDK link libs are Lib/x86. The link uses /FORCE: the 1995
headers define free functions/globals without inline/extern, so identical symbols appear in
many translation units (~124 LNK2005); /FORCE:MULTIPLE keeps the first. UNRESOLVED tolerates
a dead offline-tool factory in mech3.cpp that is never called at runtime. (Cleanup task: move
those definitions to single TUs + neutralize the dead factory, then drop /FORCE.)
Run
run\run.cmd REM boots DEV.EGG (grass / day)
run\run.cmd DBASE.EGG REM any egg in content/
The working directory must be content/ (the engine resolves BTL4.RES, VIDEO\,
BTDPL.INI, and eggs relative to cwd); run.cmd handles that. Maps available in BTL4.RES:
cavern grass rav polar3 polar4 arena1 arena2 dbase — switch via a copied egg's map= field.
Useful env-var flags (default OFF unless noted)
The authentic stack (gait, collision, real controls) is default-on; set =0 to fall back.
Debug/harness flags: BT_FORCE_THROTTLE=1 (auto-walk), BT_SPAWN_ENEMY=1 (spawn a target dummy),
BT_FORCE_FIRE=1 (auto-fire), BT_HEAPCHECK=1 (whole-heap validation — slow), BT_BSL=0 (legacy
texture decode), BT_DEV_GAUGES=1 (render the cockpit MFDs in a dev window), BT_LOG=<file>.
Interactive: WASD drive, A/D turn, Q/E torso twist, R/F torso pitch aim,
Space / 1-4 fire, X all-stop, V view, M control mode. An Xbox-type controller
works out of the box. All bindings are user-editable in content/CONTROLS.MAP (delete it to
restore the compiled-in WASD default; content/CONTROLS_NUMPAD.MAP is an alternate profile). The
complete env-gate table is in context/decomp-reference.md §6 (routed from CLAUDE.md);
controls/pad details in context/pod-hardware.md.
Multiplayer
Modern path (relay + operator console). Pods make ONE outbound connection to a relay/console, so internet play needs no per-player port forwarding and CGNAT-safe LAN discovery just works. Run the operator station:
python tools/btoperator.py # PySide6 GUI: build the mission egg (validated dropdowns),
# start the relay, watch pods arrive, assign seats, LAUNCH,
# end the timed mission, export player join.bat scripts
Players run one universal join.bat (internet, seat assigned by the relay) or join_lan.bat
(same LAN, auto-discovers the console) or play_solo.bat (offline practice) — see players/.
The pod waits patiently if the session isn't up yet. Full architecture, wire format, and the
D1 relay/UDP design: context/multiplayer.md.
Legacy mesh (two instances, one box), still supported:
instance A: btl4.exe -egg MP.EGG -net 1501 (BT_LOG=mp_a.log)
instance B: btl4.exe -net 1601 (BT_LOG=mp_b.log)
console: python tools/btconsole.py MP.EGG 127.0.0.1:1501 127.0.0.1:1601
-net <port> enables networked mode. Verified end-to-end: full entity/movement replication,
cross-pod combat + kills, per-pilot paint + callsigns, timed missions, 4-pod live sessions, and a
spectator/broadcast camera seat (hostType=1 vehicle=camera) with auto-directed coverage and
a live ranking window.
Status & continuing the work
The engine, renderer, audio, HAL, build, locomotion, collision, damage, render fidelity, the full
cockpit gauge / MFD system (every config binding resolves + every widget builds), and the
projectile / missile weapon families are done. Active fronts: per-subsystem polish (the gyroscope
integrator; the 0xBD3 message manager that gates the valve / status-message control routes) and
cross-pod MP combat. reference/decomp/ holds the raw pseudocode every reconstruction is verified
against.
Start with CLAUDE.md — it is the router into the progressive knowledge base: a quick-lookup
table pointing to the context/*.md topic files (loaded on demand), the evidence-tier and
convention rules, and context/open-questions.md for what's deferred / next. The complete
pre-restructure history is preserved verbatim in docs/PROGRESS_LOG.md; docs/*.md holds the
detailed running ledgers.