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BT412/phases/phase-02-dpl2d-reticle.md
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arcattackandClaude Fable 5 02cdfd6576 Torso: the TWIST goes LIVE -- electrical watchdog chain, centered crosshair, coherent controls (task #57/#58)
The MadCat torso twists, the view turns with it, and targeting follows.
Three reconstruction fronts closed:

THE ELECTRICAL WATCHDOG CHAIN (why the torso never powered up):
- PowerWatcher::UpdateWatch reconstructed (@004b181c, the REAL registered
  Performance -- PTR @0050f5fc; Ghidra missed the fn start): the watchdog
  MIRRORS the watched subsystem's electrical level (+0x278), brownout
  downgrade when gen output <= minVoltage% x rated.  @004b1804 relabeled
  ResetToInitialState (slot 10) -- the old "Simulation" tag was wrong.
- The factory watcher-CONNECT pass reconstructed (vtable slot +0x38,
  @004aee2c/@004b1a40 byte-identical, recovered from raw exe bytes):
  watchedLink.Add(roster[watchedSubsystem]) on the master node.  Was the
  SubProxy::Start() no-op -- every watchdog sat at 0 forever.
- MinVoltageScale = 0.01 (a 10-byte x87 literal @0x4b1924; was 1.0f =
  permanent brownout) and PowerWatcher's Derivation chains its REAL base
  HeatWatcher (the HeatableSubsystem stand-in broke IsDerivedFrom for the
  whole Torso/Searchlight/ThermalSight family).
- KB correction swept: derivation tag 0x50e604 = HEATWATCHER (not
  "HeatSink"); the btl4gaug heat-widget gate now tests it via the
  BTIsHeatWatcher bridge.

THE CROSSHAIR (task #58 forensics, 6-agent workflow + live probes):
- The VIEW is TORSO-MOUNTED: jointtorso -> jointeye -> siteeyepoint in
  every twist-capable .SKL; the camera + canopy ride the same hinge
  subtree through HingeRenderable's live matrix-stack compose -- ALREADY
  WORKING in the port.  The crosshair stays screen-centered (center IS
  the boresight); the twist reads on the tape carets/compass/radar.
- The real bug was the port's gBTAimX = tan(twist) slew (the falsified
  "body-mounted view" model): the camera already carried the twist, so
  the crosshair counter-slid to hull-forward and the fire ray with it.
  Deleted; the pick ray inherits the twist from the yawing eye basis.
- Two instrumentation traps documented (chase-eye-as-default-camera,
  BT_FORCE_TORSO clobbering real joints -> the hook now only fills
  unresolved ones); an over-correcting explicit eye compose was added on
  those false readings and retired the same day.

CONTROLS + REPLICATION:
- Q/E spring-center on release (the axis is a twist-RATE demand; the old
  hold-deflection model drifted forever); X also zeroes the axis and
  pulses the authentic torso Recenter (@004b6918).  M cycles control
  mode via the real CycleControlMode body.
- Torso update-record DIRECTION fixed: engine truth is Write=serialize /
  Read=apply; @004b6a78 is the READ (was mislabeled Write) and the
  missing WRITE @004b6a1c recovered from raw disasm (recordLength 0x1C,
  twist/vel/rate at +0x10/14/18) -- kills the replicant's 0xCDCDCDCD
  -140-degree ghost twist.
- Marching-ghost desync: 4 Standing-case guards zero stale reverse
  cycleSpeed (negative cadence passed the <= ZeroSpeed stop gate).
- Kill credit rerouted to the OBSERVED killer (lastInflictingID ->
  killer's player link) -- kills count, target K/D populates.

KB: subsystems.md (watcher chain), multiplayer.md (record direction),
combat-damage.md + gauges-hud.md + cockpit-view.md (torso-mounted view
re-correction), decomp-reference.md (new addresses + tag fix),
open-questions.md (dead capability-roster loops 2-4, snapshot CD read).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-13 13:27:49 -05:00

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5.5 KiB
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# Phase 02 — dpl2d API recovery + BTReticleRenderable reconstruction (task #35)
**Goal:** the main-view HUD (targeting reticle + up to 10 per-weapon pips).
**Status:** COMPLETE (steps 1-5 live, verified 2026-07-08). dpl2d opcode model + CallList
inline-include semantics in `game/reconstructed/dpl2d.cpp`; ctor glyph program + FUN_004cd938
tick-ladder helper transcribed in `btl4vid.cpp`; per-weapon registration via the binary's real
gate `IsDerivedFrom(0x511830 = MechWeapon::ClassDerivations)` (part_014.c:5386) — **7 pips** on
the BLH (3 lasers + 2 PPCs + 2 MissileLaunchers), AddWeapon @004cdac0 store map verified
(part_014.c:4827-4837; both state attrs are named "SimulationState", strings @51d526/51d577).
Draw hook = `BTDrawReticle(device)` after the 3D scene, cockpit view only. The binary Execute
@004cdcf0 is an UN-EXPORTED gap → Draw dynamics are best-effort [T3] (caret slide from live
target range; pip A lit on TargetWithinRange else ring B). **[SUPERSEDED: Execute @004cdcf0 was
RECOVERED task #37 (capstone disasm → reference/decomp/reticle_execute_004cdcf0.disasm.txt) —
Draw dynamics are now [T1]; pip lighting is FIRE-CYCLE state, not TargetWithinRange; crosshair
positioning re-corrected task #58 — see context/gauges-hud.md.]** Step 6 (blx_cop canopy shell)
and the PNAME1-8.bgf 3D pip meshes remain DEFERRED — tracked in context/open-questions.md.
## The recovered dpl2d recorder API (libDPL 2D display lists) [T1]
Every recorder self-identifies via its `FUN_0049a300(1, s_dpl2d_...)` debug-name string
(part_010.c). Opcodes are the first word written into the list's command buffer.
| FUN @ | dpl2d name | opcode | args |
|---|---|---|---|
| 00487f34 | NewDisplayList | — | → list handle |
| 00487fbc | OpenDisplayList (Begin) | — | (list, mode) |
| 00488030 | CloseDisplayList (End) | — | (list) |
| 00488054 | FlushDisplayList (Compile) | — | (list) |
| 004880e8 | AddOpenPolyline | 4 | closed-loop polyline begin |
| 0048814c | AddClosePolyline (loop end) | 5 | |
| 00488278 | AddOpenLines | 6 | open line-strip begin |
| 004882dc | AddClosePolyline (strip end) | 7 | |
| 00488340 | AddOpenPolypoint | 2 | point-set begin |
| 004883a4 | AddClosePolypoint | 3 | |
| 00488408 | AddPoint | 8 | (x, y) — vertex of the open primitive |
| 0048847c | AddCircle | 9 | (x, y, r, fill) |
| 00488500 | AddSetLineWidth | 0x15 | (w) — 1.0/2.0/3.0 used |
| 0048856c | AddPushState | 0x12 | |
| 004885cc | AddPopState | 0x13 | |
| 00488630 | AddSetColor | 0xf | (r, g, b) floats |
| 004886ac | AddSetColor (packed) | 0x16 | (argb?) |
| 00488718 | AddSetMatrix | 0x10 | 6 floats (2x3 affine) |
| 004887b0 | AddConcatMatrix | 0x11 | 6 floats + flag |
| 00488850 | AddCallDisplayList | (nested) | (list) — glyph reuse |
| 004888c0 | AddFullScreenClipRegion | | |
| 00488b80 / 00488bac | 2x3 matrix build: identity / set-translate(x,y) | — | local helpers feeding AddSetMatrix |
⚠ CORRECTION to the earlier AddWeapon recon comments: the "PushMatrix/MoveTo/PopMatrix"
triple is actually **AddOpenPolypoint / AddPoint / AddClosePolypoint** = "draw a POINT" —
`game/reconstructed/dpl2d.cpp`'s current Push/Move/Pop interpretation must be reworked to
this opcode model (points, open/closed polylines, circles, width, color, push/pop state,
set/concat matrix, nested list calls) and its `dpl2d_ExecuteList` renderer extended to draw
them (XYZRHW screen-space lines/points/fans; state save/restore already present).
## BTReticleRenderable — what the ctor builds (@004cc40c, part_014.c:4362) [T1 read]
- Calibration from ctor params/templates: pip origin/bias/scale (+0x1fc..0x234 in class
terms), min/max range from templates, `rangeScale = (clamped - lo) / (hi - lo)`.
- Loads **PNAME1-8.bgf** (all ship in VIDEO/GEO) — pip/number meshes — plus a 3D
renderable chain (FUN_00489708/489724/48ab0c/491cc4... — the dpl *3D* overlay object at
0.12 scale) — the reticle has BOTH a 3D marker component and the 2D display lists.
- Builds ~15 display lists: the master list (param_1[0x98]) composed of nested glyph lists
via AddCallDisplayList: crosshair dot cluster (AddPoint xy at ±0.04/±0.1 = the dotted
cross), heavier ±0.1..0.16 tick cross at width 3, two tick-LADDERS via FUN_004cd938
(count 0xd=13 / 0x15=21 ticks, spacing/geometry from the calibration constants at
[0x7f..0x88]: 0.35/0.25/0.5/±0.008/0.016...), side arrow polylines (the 4-vertex
closed arrows at the ladder ends), an arc segment (AddCircle partial at 0.03?), and the
heading/aim sub-lists ([0x9a..0xa1, 0xb6..0xba]) positioned by AddSetMatrix translates.
- FUN_004cd938 = the tick-ladder builder (count, flag, scale, x, y, step, minor/major
tick half-lengths) — transcribe next.
## Remaining steps
1. Rework dpl2d.cpp to the opcode model + extend ExecuteList (lines/points/polys/matrix/call).
2. Transcribe the ctor's glyph program into BTReticleRenderable::BTReticleRenderable
(+ FUN_004cd938 helper) with the authentic constants.
3. Read + transcribe Execute (vtable PTR_LAB_0051db44 — find the Execute slot; per-frame:
withinRange attr reads → pip list visibility/colors, aim/heading matrix updates).
4. Read the 1996 caller wiring (FUN_004cef28's inside path: the ctor's 15 args + the
AddWeapon per-weapon argument sourcing) and reproduce in MakeMechRenderables.
5. Draw hook: the engine already calls mReticle->Execute() per frame (L4VIDEO ~6562);
or execute from the BT renderer after the 3D scene; dpl2d_ExecuteList(device).
6. The cockpit canopy shell (blx_cop, punch cutout) black-enclosure fix (BT_INSIDE_COCKPIT=1).