Determined the authentic behavior from the decomp (HudSimulation + Emitter,
part_013.c:5619-5670 / 7689-7778) and fixed two regressions the players hit:
(A) You could only fire when a MECH was locked (couldn't fire at nothing).
(B) Buildings/structures/ground stopped moving the range axis; only mechs did.
AUTHENTIC (T1): a weapon discharges iff the target slot mech+0x388 != 0
(Emitter::FireWeapon FUN_004bace8:7727), and 0x388 is whatever the BORESIGHT
designates -- mech OR world geometry -- NOT a manual mech lock. The RANGE readout
(HUD+0x1ec) moves for ANY designated target (mech OR structure/ground); the LOCK
ring is mech-only (target has a damage-zone table, HudSim :5619). So the pod
'fired freely at nothing' and buildings moved the range caret.
ROOT CAUSES (both content-triggered, not a targeting-code change):
1. arena1's ONLY class-42 world entity is the 10000x10000 FLAT GROUND plane at
y=0, MISNAMED 'sky' -- SkippedName filtered it out by name, so BuildTables
ingested 0 geometry and gBTTerrainEntity stayed null -> nothing groundable ->
mech-only targeting. (LAST.EGG rewrite ~bb795e2 lost whatever terrain the
working scene had.)
2. A boresight that hit nothing set MECH_TARGET_ENTITY=0 -> no discharge.
FIXES:
- btvisgnd.cpp: geometry-aware skip -- keep a wide, near-flat, near-ground plane
even if name-skipped (it is the arena floor); still skip true domes/backdrops.
Adds mesh y-bounds. arena1 now ingests 1 ground instance (was 0).
- btl4vid.cpp: capture ANY world-geometry entity as the non-mech pick sentinel
(the default render case is world-only), not only Terrain-derived ones.
- mech4.cpp: FIRE-AT-NOTHING -- when nothing pickable is hit, designate a
max-range point (1200, the HUD default 0x44960000) along the boresight using
the world sentinel, so 0x388 != 0 and the weapon discharges (no zone damage /
no lock ring, since the sentinel has no damage-zone table -- mechs only).
Verified autonomous: arena1 ground ingested; [target] shows 'fire-at-nothing
(max-range designate)'; weapon discharges at empty space ([fire] explode
resolved); range axis (sShownRange->BTSetHudTargetRange) slides to the designated
distance. Diagnostic: BT_GROUND_LOG (world-geometry ingest + skip reasons).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
