User report: the ground shadow painted OVER the mech's feet. Root cause: the
flat quad + big depth-bias (-0.004 ~= 2-4 world units) workaround for slope
burial -- a bias big enough to beat the TERRAIN also beat the FEET in the
depth test, and the shadow drew in the late alpha-blend pass (after the mech),
so z-arbitration was the only layering control.
Fix, four co-dependent parts (user-verified live: feet on top, opaque,
survives inclines/declines):
- TILT (mech.cpp UpdateShadowJoint): apply the SKL's own contract for
jointshadow ("apply terrain angle to pitch and roll") -- quad up aligned to
the surface normal via an orthonormal basis fed to the ENGINE's own
LinearMatrix->EulerAngles conversion. Hand-derived Euler signs are exactly
how the prior tilt attempts "dug into the hillside"; the engine conversion
is convention-proof. ~35 deg cliff-guard cap.
- SAMPLER (mech4.cpp): surface gradient from the collision probes PLUS
BTVisualGroundLift per probe -- the quad hugs the VISIBLE terrain, whose
lift varies across a slope; world->local rotation by the TRUE yaw from
localToWorld, not the drift-prone gDriveHeading mirror (the task-#48 bug
class). BT_SHADOW_LOG traces the normals.
- DRAW ORDER (new PASS_SHADOW, l4d3d.h/L4VIDRND/L4VIDEO): shadows draw
between the STATIC terrain and the DYNAMIC opaque bodies -- the classic
decal order. The mech, drawn after, z-passes over the shadow: the bias
can never paint the shadow over the feet, structurally.
- BIAS pairing (L4D3D.cpp): tilt on (default) -> decal epsilon -0.0008;
BT_SHADOW_TILT=0 flat fallback -> the old -0.004. BT_SHADOW_BIAS overrides.
KB (locomotion.md): the four-part arrangement recorded as co-dependent, with
the gait-desync-symptom diagnostic hint retained.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The aim/pick ray was the active RENDER EYE's view direction, which made a
mech unable to aim at a distant enemy:
(a) it inherited the mech BODY pitch -- on a slope the body tilts ~8 deg to
conform to terrain, so the boresight pointed that far DOWN and the pick
ray hit the ground ~50-100m short of the target (groundPicks, never
mechPicks); and
(b) in CHASE view (the default) it was the elevated behind-the-shoulder
camera, so the ray started over the mech's shoulder and flew high.
Fix (L4VIDRND DPLEyeRenderable::Execute, the BTSetAimCamera publish):
- LEVEL the boresight: drop the view-direction pitch and rebuild an upright
basis (world +Y up) -- the guns fire along the mech's gyro-stabilized
HORIZONTAL heading, not the terrain-pitched body. Reticle X still carries
the torso twist (BTTwistToReticleX); reticle Y any elevation.
- ANCHOR the ray origin at the mech's TORSO (myEntity->localToWorld
translation + ~5) instead of the render eye, so it is correct in BOTH the
chase (default) and cockpit views.
Verified end-to-end: solo, enemy 120m ahead, BOTH chase and cockpit view ->
[target] "MECH under boresight ... mechPicks=59 groundPicks=0" -> beam ->
*** DESTROYED. Also proved PickRayHit resolves a REPLICANT when aimed at it
(hit=1 at 757m, 2-node run).
mech4: BT_GOTO="enemy" test aid now chases the nearest peer of ANY instance
(solo dummy OR replicant), not just replicants.
Still open (locomotion, not aim/MP): BT_GOTO/BT_AUTODRIVE stall short of the
enemy, so an AUTOMATED 2-node kill via the real beam isn't demonstrated yet
(the FORCE_DMG hook still is). A human can now aim correctly in the default
view. Solo un-regressed; build clean; KB validator clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The engine Reticle model (MUNGA/RETICLE.h [T0]) reconstructed end to end:
- Mech::targetReticle is a real Reticle member bound to the TargetReticle
attribute (0x1d), per the RP VTV analog (VTV.h targetReticle).
- Crosshair slew: mouse -> client rect -> reticle coords (the pod stick
free-aim channel's dev-box stand-in); BT_AIM="x y" pins it headless.
LMB fires lasers / RMB missiles (alongside SPACE/CTRL).
- Pick ray: the ACTIVE eye publishes pos + LookAtRH basis (BTSetAimCamera,
L4VIDRND view-write site) + the render loop publishes proj._22;
BTGetAimRay builds the world ray, Mech::PickRayHit slab-tests it against
the collision template's ExtentBox via the engine's BoundingBox::HitBy
(local frame; clips the Line at entry) -> world hull point.
- Designation: the mech under the crosshair designates (sticky; re-hover
refreshes; cleared when the target leaves the roster at burial); the
entity target slots 0x37c/0x388/0x38c feed the whole weapon path.
- Aimed fire: while HOT the impact point is the PICKED hull point -> the
STEP-6 cylinder lookup resolves the zone under the crosshair (verified:
center-aim -> head-band zone 13 dominant). Off-crosshair the sticky
designation converges on center mass.
- HUD: the aim group draws at the slewed position ([0x9a] translate,
contained by push/pop); the designator ring tracks the target's
projected point (subB9 hot / subB8 designated, BTProjectToReticle);
edge arrows when off-screen/behind.
- AUTHENTIC gating: no fire arc exists in the binary (FireWeapon fires
whenever HasActiveTarget, part_013.c:7758) -> BT_FIRE_ARC is now an
explicit OPT-IN presentation clamp; the hardwired gEnemyMech lock and
the projectile path's gEnemyMech fallback are removed.
- Fixed en route: every renderable rebuild stomped mCamera back to the
chase eye (start-inside silently lost the cockpit camera; the aim feed
exposed it). BTL4VideoRenderer::mViewInside persists the chosen view.
Verified headless: BT_AIM="0 0" -> HOT lock, pick hits the hull face at
exact range, aimed zones resolve; BT_AIM="0.8 0.3" -> no lock, zero
damage, zero missile launches; kill chain completes to wreck + smoke.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- V toggles the authentic cockpit eyepoint <-> the chase camera. Both eyes
coexist; DPLEyeRenderable::Execute now writes the VIEW only when it IS
mCamera (unconditional writes let the last-executed eye stomp the toggle).
- EyepointRotation is a real zeroed EulerAngles member on Mech (was bound to
the shared junk attrPad -- the eye composes this attribute into the view
EVERY frame, so the cockpit camera was rotated by garbage: the canted
horizon, then the black screen). The eye-slew systems write it later.
- The cockpit eye mounts at the eyepoint's REST position with a clean upright
forward basis on the tree root (the live joint chain fed it the site tilt +
torso pose; authentic pitch/yaw is the deferred gyro eye chain).
- The inside view swaps the player to the INSIDE skeleton mesh set
(SkeletonType_A): 19 body segments hide, exactly one mesh remains --
blx_cop.bgf, the authentic cockpit canopy shell around the eyepoint. It
currently renders as a black enclosure (the black-screen report), so it is
HIDDEN pending its interior/punch-material rendering (BT_INSIDE_COCKPIT=1
shows it for that work). Damage gstates respected in both directions;
RemakeEntity keys off the DISPLAYED skeleton.
- Dev: BT_START_INSIDE=1 starts in the cockpit view.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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>
