ShieldManager's fallback (no ShieldEnvelope yet, e.g. every ship prefab
before the operator hand-rigs it per Q5) hard-failed to a fixed
Vector3.forward direction with a per-hit Debug.LogError. That silently
changed behaviour for every ship in the game until the operator edits
Longinus.prefab/Djinni.prefab on their own schedule -- worse than either
the deleted code or a loud one-time failure.
Extract ShieldEnvelope's local-direction primitive into two static,
no-component-required entry points -- SurfaceDirection(Transform, Vector3)
and LegacyLocalSurfacePoint(Transform, Vector3) -- so both FieldDriver's and
ShieldManager's fallbacks go through one owner instead of each re-deriving
the pre-Cut-2 formula by hand. ShieldManager's fallback now reproduces the
deleted normalize(shield.transform.InverseTransformPoint(point)) formula
exactly via the shared static, logging once (a warning, not a per-hit
error). FieldDriver's fallback is rewired onto the same static rather than
its own inline copy of the maths.
Documented, not silently assumed: FieldDriver's "envelope present" branch
(envelope.ProjectToSurface, world-space) and its fallback (the legacy local-
space formula) are only numerically identical when the carrier's transform
has zero position and identity rotation -- true of the one FieldDriver
carrier in the tree today, not true in general. This is a characteristic of
Cut 2 as scoped by the map (FieldDriver.cs:125 reads envelope.ProjectToSurface
directly, per the map's own text), not something this fix introduces or
resolves; flagged so nobody assumes the two branches are interchangeable for
a future non-origin, non-identity FieldDriver carrier.
ShieldPanelCut2Verify.CheckLegacyFallbackFormulas pins both static entry
points against an independent re-derivation of the exact pre-Cut-2 formulas,
on a carrier with a non-trivial transform (nonzero position, non-identity
rotation) so the check isn't vacuous. mutation_tests_shield_panel_cut2.py
gained two cases: SurfaceDirection collapsing back to a fixed Vector3.forward
(the exact regression fixed here), and LegacyLocalSurfacePoint collapsing to
the raw, untransformed world point -- both correctly fail the probe.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
FieldDriver derived the shield ellipsoid from its own transform.localScale;
ShieldManager derived it independently from the Shield prefab instance's
transform, doing the same normalise-and-project by hand against a different
object. Add ShieldEnvelope as the one reader of a transform's centre, radii,
surface projection, and true outward normal (derived, not authored, per R6 --
no second copy of numbers the physical MeshCollider already owns), and switch
both consumers onto it, deleting their hand-rolled projections.
Radii read the attached collider mesh's own bounds.extents per axis rather
than assuming a flat 0.5 or 1.0: Shield.prefab's Icosphere collider measures
(0.0095106, 0.01, 0.01), not a uniform round number, and the cubesphere's
collider measures exactly (1,1,1) -- confirmed by a throwaway batchmode probe
against the actual mesh assets, not guessed.
SurfaceNormal is not normalize(p): a non-uniform ellipsoid's true normal is
the gradient of the implicit surface, transformed by rotation and the INVERSE
of lossyScale (a normal is a covector). The first implementation used
TransformDirection (rotation and forward scale) and the batchmode probe's
finite-difference gradient check caught it immediately -- exactly the
plausible-looking-wrong-answer failure mode the cut map called out by name.
Both original consumers keep normalize(p)-equivalent behaviour via the new
SurfaceDirection method, since they only ever wanted a direction.
FieldDriver falls back to its pre-cut formulas (logged once) when no
ShieldEnvelope is present, since it has no guaranteed carrier yet.
ShieldManager does not: every object that carries it gets an envelope in this
cut, so a missing one logs an error and degrades to a fixed direction rather
than recomputing a second projection.
No prefab or scene file is touched here (Q5: the operator rigs prefabs and
scenes by hand); ShieldPanelCut2Verify's batchmode probe instead builds
synthetic transforms carrying Longinus's and Djinni's actual override values
plus the real Icosphere mesh, and proves ProjectToSurface lands exactly on the
ellipsoid and SurfaceNormal matches a finite-difference gradient to 1e-3.
mutation_tests_shield_panel_cut2.py mutates SurfaceNormal three ways (back to
normalize(p), back to TransformDirection, and a flattened 0.5 extents factor)
and confirms the probe goes red for each, naming the reason.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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