Joe DiPrimaandClaude Opus 5
5a425320b7
Oracle, night 7: "Unable to damage the foot panels on Loki via direct fire from
front or side. Was able to damage on Thor."
FIRST, THE MECHANISM -- it is not what the issue assumed (missing collision
geometry). A direct-fire hit gets its zone one of two ways, decided at
Mech::TakeDamageMessageHandler by `invalidDamageZone`:
AIMED (invalidDamageZone=0): the zone rides in on the message from the
per-part aim pick, MechSegmentPick (#73, btl4vid.cpp).
UNAIMED (invalidDamageZone=1): DamageLookupTable::ResolveHit runs the authored
cylinder lottery -- impact HEIGHT picks a layer, ANGLE picks a pie
slice, and a weighted random roll picks the zone from that slice.
Measured live, both paths are in use: the Thor logged 16 unaimed hits
(invalidZone=1 zone=-1 -> ResolveHit) alongside aimed ones carrying real zones.
THE FINDING. MechSegmentPick is a BOUNDING-SPHERE test whose primary key is
SMALLEST RADIUS WINS -- a larger sphere can never beat a smaller one the ray also
grazes. The leg spheres, dumped in world space and IDENTICAL on both chassis:
knee centre y=1.868 r=1.505 spans y 0.364 .. 3.373
toe centre y=0.302 r=1.689 spans y -1.387 .. 1.991
The toe sphere is BIGGER than the knee's and they overlap heavily, so the toe can
only win where the ray misses the knee sphere outright -- i.e. below y=0.364.
Against a reference height of 11.16 that is a 0.36-unit window, **3.3% of the
mech's height**, and it sits right on the ground. Everywhere else a shot at the
foot is credited to the LEG. That is the reported symptom.
This is a PORT ARTIFACT, not authentic: btl4vid.cpp's own comment concedes the
sphere test approximates "the per-part semantic the 1995 mesh intersection
produced". Real mesh intersection has no such interference -- aiming at the foot
mesh hits the foot.
NOT EXPLAINED, and stated plainly: the per-CHASSIS asymmetry. Loki and Thor have
identical leg spheres, identical foot geometry (LOK_LFOT.BGF and THR_LFOT.BGF are
both 3082 bytes with the same token layout), and identical foot layers in their
damage tables (only the upper/cockpit layers differ). So nothing found here says
the Loki should behave differently from the Thor. The bench could not settle it
because BT_AIM moves the drawn RETICLE, not the pick ray -- there is currently no
harness to aim the pick at a chosen height. That harness is the next step.
Diagnostics added:
[pickgeom] one-shot dump of every pick sphere in WORLD space (zone, r, centre)
[pickcand] which spheres a ray actually threaded, their perpendicular d, and
which won -- the probe that makes "smallest wins" visible
[dmgtable] the whole authored DamageLookupTable: layers, slices, zone weights
[dmgresolve] per hit: localY, heightRef, layer, theta, resolved zone
[cylgate] invalidDamageZone / table pointer / incoming zone at the gate
(the last three under BT_DMGTABLE_LOG, the first two under BT_PICK_LOG)
plus scratchpad/night8/footpick.sh.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
27 lines
1.3 KiB
Bash
27 lines
1.3 KiB
Bash
#!/usr/bin/env bash
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# #92: "Unable to damage the foot panels on Loki via direct fire ... was able to
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# damage on Thor" (Oracle). The aimed per-part pick (MechSegmentPick, #73) is a
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# BOUNDING-SPHERE test whose primary key is SMALLEST RADIUS WINS -- a larger
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# sphere can never beat a smaller one, whatever the aim. So if a chassis's foot
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# sphere is bigger than its lower-leg sphere, every ray that threads both is
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# credited to the leg and the foot is unhittable. Dump the spheres per chassis.
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set -x
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. /c/git/bt411/scratchpad/night6/bench_common.sh
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cd /c/git/bt411/content || exit 1
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V="$1"
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taskkill //F //IM btl4.exe > /dev/null 2>&1
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sleep 2
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sed "s/^map=.*/map=grass/; s/^time=.*/time=day/; 0,/^vehicle=.*/s//vehicle=$V/" MP.EGG > FOOT.EGG
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LOG=footpick_$V.log
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rm -f "$LOG"
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export BT_PICK_LOG=1 BT_DMGTABLE_LOG=1
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export BT_START_INSIDE=0 # external: the whole mech tree is built + shown
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export BT_SPAWN_ENEMY=1 # target of the SAME chassis (uses the mission model)
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export BT_GOTO=enemy BT_GOTO_STOP=25 # close in so the foot subtends a real angle
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export BT_AIM="${2:-0 -0.35}" # aim LOW -- at the feet
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export BT_AUTOFIRE=1 BT_DMG_LOG=1 # shoot it and log the resolved zone
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bt_launch "$LOG" FOOT.EGG 0x03
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sleep 70
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taskkill //F //IM btl4.exe > /dev/null 2>&1
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sleep 2
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