arcattackandClaude Opus 4.8
7b7d465e5e
Clean, self-contained extraction of the BattleTech-specific work from the
reverse-engineering workspace -- engine + game + content + build, with nothing
from Red Planet or the raw archive dumps. Builds green (Win32) and runs the
single-player drive->animate->target->fire->damage->destroy loop out of the box.
Layout:
engine/ MUNGA + MUNGA_L4 shared 2007 engine, carrying our BT render/loader
work (bgfload/L4D3D/L4VIDEO: BSL bit-slice decode, LOD/ground/shadow
models) + image codec; the minimal rp/ headers the audio HAL needs
game/ reconstructed BT logic + surviving-original BT source + fwd shims
+ WinMain launcher
content/ full runtime tree (BTL4.RES, VIDEO/, GAUGE/, AUDIO/, eggs, BTDPL.INI)
docs/ format specs + reconstruction ledgers
reference/ raw Ghidra pseudocode (recon source-of-truth) + decomp exporter
tools/ MP console emulator + map/resource scanners
One top-level CMake builds munga_engine lib + bt410_l4 game lib + btl4.exe.
All paths relativized (186 fwd shims + ~437 CMake abs paths -> repo-relative);
DXSDK is the one external, overridable via -DDXSDK. Verified: builds to a
byte-identical 2.27MB exe and runs combat (TARGET DESTROYED, 0 crashes) against
the bundled content.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
318 lines
13 KiB
C++
318 lines
13 KiB
C++
//============================================================================//
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// File: missile.cpp //
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// Project: BattleTech //
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// Contents: Guided self-propelled projectile entity (Missile : Projectile) //
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//----------------------------------------------------------------------------//
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// Copyright (C) 1995, Virtual World Entertainment, Inc. All Rights reserved //
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// PROPRIETARY AND CONFIDENTIAL //
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//============================================================================//
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//
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// RECONSTRUCTED from the shipped binary. Behaviour follows the Ghidra
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// pseudo-C in part_013.c; there is NO surviving missile.cpp -- only MISSILE.TCP
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// (Missile::TestClass) and PROJTILE.TCP guide the member/method naming. Each
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// non-trivial method cites the originating @ADDR. Coverage is partial by
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// design (Missile is the lowest-priority of the three classes; it has no HPP).
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//
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// confident : ctor @004bf5b4 (subsystem roster build), MoveAndCollide skeleton
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// @004bef78, WriteUpdateRecord @004bef4c
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// best-effort: member names/offsets past the Projectile base, the collision
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// + detonation branch (FUN_0042291c / FUN_004be078)
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// excluded : the Projectile base ctor @004be1bc and the 0x41xxxx/0x42xxxx
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// Entity engine vtable slots
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//
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// Decoded MoveAndCollide tuning constants (.rdata @004bf594..@004bf5b0):
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// 0x40000000 = 2.0f 0x38d1b717 = 1.0e-4f 0x40800000 = 4.0f
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// 0x3dcccccd = 0.1f 0x41200000 = 10.0f 0xbf800000 = -1.0f
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//
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// Helper-function name mapping:
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// FUN_004be1bc Projectile base constructor (vtable @00512a5c)
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// FUN_004bec34 Seeker::Seeker FUN_004be7c4 MissileThruster::MissileThruster
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// FUN_0042291c world collision query FUN_004be078 spawn explosion/Damage entity
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// FUN_00421b2c Entity::IntegrateMotion FUN_00421bac Entity::AdvanceModel
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// FUN_0042061c Entity::Retire FUN_00402298 operator new
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// FUN_00408644 Vector3D = a - b FUN_004086ac scaled add
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// FUN_004dd138 sqrt() FUN_0041a1a4 IsDerivedFrom
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//
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#include <bt.hpp>
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#pragma hdrstop
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#if !defined(MISSILE_HPP)
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# include <missile.hpp>
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#endif
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#if !defined(SEEKER_HPP)
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# include <seeker.hpp>
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#endif
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#if !defined(MISTHRST_HPP)
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# include <misthrst.hpp>
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#endif
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#if !defined(TESTBT_HPP)
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# include <testbt.hpp>
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#endif
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//
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// MoveAndCollide tuning constants (read-only globals in the decomp).
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//
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static const Scalar MissileLifeWarn = 2.0f; // _DAT_004bf594 age-ratio dead threshold
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static const Scalar MissileSteerEps = 1.0e-4f;// _DAT_004bf598/9c/a0 steering deadband
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static const Scalar MissileTurnGain = 4.0f; // _DAT_004bf5a4
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static const Scalar MissileDriftGain = 0.1f; // _DAT_004bf5a8
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static const Scalar MissileMinSpeed2 = 10.0f; // _DAT_004bf5ac/a8 min squared-speed before fizzle
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static const Scalar MissileDead = -1.0f; // _DAT_004bf5b0
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//###########################################################################
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//###########################################################################
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// Missile
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//###########################################################################
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//###########################################################################
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//#############################################################################
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// Decompiler-artifact stand-ins.
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//
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static char DAT_00512d48[0x368] = { 0 }; // default streamed-entity record
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//#############################################################################
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// Shared Data Support
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//
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Derivation
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Missile::ClassDerivations(
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&Projectile::ClassDerivations,
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"Missile"
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);
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Receiver::MessageHandlerSet Missile::MessageHandlers;
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Simulation::AttributeIndexSet Missile::AttributeIndex;
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Missile::SharedData
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Missile::DefaultData(
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&Missile::ClassDerivations,
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Missile::MessageHandlers,
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Missile::AttributeIndex,
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Missile::StateCount,
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&Missile::Make
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);
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Entity *Missile::Make(MakeMessage * /*creation_message*/)
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{
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return 0;
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}
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//#############################################################################
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// Allocation
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//
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// @004bf8bc Missile::New(spawn_context) -- allocate 0x368 bytes and construct
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// with the default streamed-entity record &DAT_00512d48.
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//
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Missile *Missile::New(int spawn_context)
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{
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Missile *missile = (Missile *)::operator new(0x368); // FUN_00402298
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if (missile != 0)
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missile = new(missile) Missile(spawn_context, DAT_00512d48); // @004bf5b4
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return missile;
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}
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//#############################################################################
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// Construction
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//
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// @004bf5b4 Missile::Missile(...)
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//
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// Chains the Projectile base ctor (which copies the launch transform,
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// velocity and segment data out of the spawn descriptor), stamps the Missile
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// vtable, resolves the detonation model + lifetime out of the entity model
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// record, then constructs the two hosted subsystems into a freshly allocated
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// 2-entry roster:
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// roster[SeekerSubsystem] = new Seeker("Seeker", target, offset)
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// roster[MissileThrusterSubsystem] = new MissileThruster("MissleThruster")
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//
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Missile::Missile(int owner, const char *spawn_descriptor)
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:
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// Projectile base ctor (Entity transform, velocity, model, segment).
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Projectile(owner, spawn_descriptor) // @004be1bc
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{
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// vtable installed by the compiler (PTR_FUN_00512f2c)
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mass = 1.0f; // model mass (avoid /0)
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ageFraction = 0.0f; // @0x344 this[0xd1]
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targetConnection = ResolveTargetConnection(owner); // @0x34c this[0xd3]
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targetOffset = LaunchAimOffset(owner); // @0x350 this[0xd4..0xd6]
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age = 0.0f; // @0x35c this[0xd7]
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simulationFlags |= 0x10; // this[0x0a] |= 0x10 (guided)
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// pull lifetime / thrust / detonation-mode out of the entity model record
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const ModelRecord *model = ResolveModel(); // FUN_00407064 chain
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lifetime = model->maxTimeOfFlight; // @0x340 this[0xd0] (model +0x44)
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thrustScale = (Scalar)Sqrt(model->thrust / mass); // @0x348 this[0xd2] (model +0x48)
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detonationFlag = model->detonationMode; // @0x364 this[0xd9] (model +0x50)
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// allocate the 2-entry subsystem roster
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subsystemCount = SubsystemCount; // @0x124 this[0x49] = 2
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subsystems = (Subsystem **)::operator new(SubsystemCount * sizeof(Subsystem *)); // @0x128 this[0x4a]
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// slot 0: Seeker (homing guidance) -- "Seeker" @00512e1e
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subsystems[SeekerSubsystem] =
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(Subsystem *)new Seeker((Missile *)this, 0, 0, (Entity *)targetConnection,
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Point3D(targetOffset.x, targetOffset.y, targetOffset.z)); // @004bec34
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// slot 1: MissileThruster (propulsion) -- "MissleThruster" @00512e25
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subsystems[MissileThrusterSubsystem] =
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(Subsystem *)new MissileThruster((Missile *)this, 1, /*resource*/0); // @004be7c4
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// Install the guided per-frame integrator as this entity's active Performance.
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// The Projectile base ctor installed the plain Projectile::MoveAndCollide;
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// the Missile overrides it so the flight entity homes + collides each frame.
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// (Without this re-install the missile would coast on the unguided base pass.)
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SetPerformance(&Missile::MoveAndCollide); // @004bef78
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// hand ourselves to the spawning launcher's projectile slot
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// (FUN_0049fb54 chain: launcher->currentProjectile = this) @004bf5b4 tail
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}
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//#############################################################################
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// Destruction
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//
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// @004bf890 ~Missile() -- restores the Missile vtable, destroys the hosted
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// subsystems via the Projectile base destructor (@004be358).
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//
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Missile::~Missile()
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{
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// vtable reset + base ~Projectile chaining handled by the compiler.
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if (subsystems != 0)
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::operator delete(subsystems);
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}
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//#############################################################################
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// Per-frame integration
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//
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// @004bef78 Missile::MoveAndCollide(time_slice)
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//
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// 1. Age the missile (age += time_slice) and update ageFraction. Past the
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// lifetime / below MissileMinSpeed2 the missile flags itself dead
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// (flags |= 1) and is retired by the entity manager.
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// 2. Sample the Seeker lead point and the target's relative geometry; apply
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// a per-axis steering impulse (turn toward the lead, gain MissileTurnGain,
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// deadband MissileSteerEps) into the velocity (this+0x1dc) plus the
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// MissileThruster acceleration (this+0x234 -> this+0x1e8).
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// 3. Integrate the motion (FUN_00421b2c / FUN_00421bac) and run the world
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// collision query FUN_0042291c.
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// 4. On a hit, spawn the explosion + Damage entity (FUN_004be078, streamed
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// ClassID 0x5C) at the impact point and retire; otherwise advance the
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// smoke-trail model and bounds-check.
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//
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void Missile::MoveAndCollide(Scalar time_slice)
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{
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age += time_slice; // @0x35c this[0xd7]
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// dead if it has out-lived its flight envelope
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ageFraction = (age <= lifetime) ? age / lifetime : 1.0f; // @0x344
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if (age > lifetime)
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simulationFlags |= 1;
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// --- drive the hosted subsystems for this slice -----------------------
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// In the shipped binary the Seeker / MissileThruster Performance work is
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// folded into this integrator (it samples their state out of the roster),
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// so rather than ticking them through a separate subsystem loop we advance
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// them explicitly here: re-lead the (moving) target and bleed burn time.
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Seeker *seeker = (Seeker *)subsystems[SeekerSubsystem];
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MissileThruster *thruster = (MissileThruster *)subsystems[MissileThrusterSubsystem];
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if (seeker != 0)
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seeker->FindTarget(time_slice); // @004beae4 LeadTarget
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if (thruster != 0)
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thruster->MissileThrusterSimulation(time_slice); // bleed burnTimeRemaining
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// --- guidance: build steering toward the Seeker's lead point ----------
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Vector3D forward;
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GetForward(forward); // FUN_0040d150(.., +0x100)
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const ThrusterState *thr =
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(const ThrusterState *)this->subsystems[MissileThrusterSubsystem]; // this+0x250
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// vector from the missile's facing to the Seeker's lead/aim point (@0x1c4)
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Vector3D toLead;
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toLead.Subtract(seeker->targetPosition, forward);
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// per-axis: turn-rate vs drift gain depending on alignment, squared error
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Vector3D steer;
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for (int axis = 0; axis < 3; ++axis)
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steer[axis] = (fabs(toLead[axis]) <= MissileSteerEps)
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? toLead[axis] * MissileDriftGain
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: toLead[axis] * MissileTurnGain;
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Scalar thrustAccel = (thr != 0) ? thr->acceleration : 0.0f; // FUN_004086ac
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velocity.x += steer.x * thrustAccel; // this+0x1dc
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velocity.y += steer.y * thrustAccel;
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velocity.z += steer.z * thrustAccel;
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// thruster acceleration (this+0x234) folded into velocity (this+0x1e8)
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thrustVelocity.x += thrusterAxis.x * thrustImpulse; // this+0x1e8 += this+0x234 * this+0x1d0
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thrustVelocity.y += thrusterAxis.y * thrustImpulse;
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thrustVelocity.z += thrusterAxis.z * thrustImpulse;
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// --- integrate + collide ---------------------------------------------
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IntegrateMotion(); // FUN_00421b2c
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AdvanceModel(time_slice); // FUN_00421bac
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Entity *hit = CollisionQuery(time_slice); // FUN_0042291c
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if (hit == 0)
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{
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// no impact this frame -- bounds check vs MissileMinSpeed2 elsewhere
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}
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else
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{
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Retire(); // FUN_0042061c
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// spawn explosion + Damage entity at impact (FUN_004be078, ClassID 0x5C)
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SpawnDetonation(hit);
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simulationFlags |= 1;
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}
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}
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//#############################################################################
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// WriteUpdateRecord
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//
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// @004bef4c vtable slot 7 -- chains the Entity base writer (FUN_004225a4),
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// stamps record tag 0x78 and appends the detonation/age word (this+0x35c).
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//
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void Missile::WriteUpdateRecord(UpdateRecord *message, int update_model)
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{
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Entity::WriteUpdateRecord(message, update_model); // @004225a4
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message->recordID = 0x78; // record tag
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// the shipped record also appends the age word (this+0x35c) for replication.
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}
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//#############################################################################
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// TestInstance
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//
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Logical Missile::TestInstance() const
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{
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return Projectile::TestInstance();
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}
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//#############################################################################
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// Recovered helpers (engine/model plumbing rendered as decomp artifacts).
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//
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void Missile::GetForward(Vector3D &out)
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{
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out = Vector3D(0.0f, 0.0f, -1.0f); // FUN_0040d150 (facing -Z)
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}
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void *Missile::ResolveTargetConnection(int /*owner*/)
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{
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return 0; // resolved target/launcher link
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}
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Vector3D Missile::LaunchAimOffset(int /*owner*/)
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{
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return Vector3D(0.0f, 0.0f, 0.0f);
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}
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const Missile::ModelRecord *Missile::ResolveModel()
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{
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// FUN_00407064 chain -- the entity model record (lifetime/thrust/detonation).
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static const ModelRecord defaultModel = { 10.0f, 1.0f, 0 };
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return &defaultModel;
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}
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void Missile::SpawnDetonation(Entity * /*hit*/)
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{
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// FUN_004be078 -- spawn the explosion + Damage entity (streamed ClassID 0x5C)
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// at the impact point. Cross-family (entity factory / damage) integration.
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}
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