The user brought up Ghidra; its decompiler (patchmem.gpr, full PDB)
resolved the Binary-Ninja `test ah,5` x87 branch-sign ambiguity that
blocked the desk read. CSphere::slide_sphere (0x00537440) decompiles
cleanly to:
fVar3 = |cross(collisionNormal, contactPlane.N)|²;
if (::F_EPSILON <= fVar3) { // crease exists
... offset = cross * dot(cross,gDelta)/fVar3;
if (|offset|² < ::F_EPSILON) return COLLIDED_TS; // degenerate guard
... add_offset_to_check_pos -> SLID_TS
}
Retail compares the SQUARED magnitudes against F_EPSILON
(0.000199999995 ~= 0.0002 = PhysicsGlobals.EPSILON). Our port compared
against EpsilonSq (0.0002^2 = 4e-8) - a ~5000x too-tight threshold (the
BN pseudo-C rendered the comparison as `test ah,5` after an x87 FCMP,
which is sign-ambiguous; agent reads disagreed). Fixed both comparisons
at TransitionTypes.cs:3098,3105 to EPSILON.
Effect: crease-exists now needs >=0.81 deg between the wall and contact
normals (was 0.011 deg - which routed near-parallel pairs through the
numerically unstable projection); the degenerate guard now hard-stops
slides under ~1.41 cm like retail (was 0.2 mm). Branch POLARITY was
already correct - no change there.
No regression: full physics suite (612) + full Core (1443) green. Not a
register deviation (no row existed; this is an undocumented porting
error corrected to match retail).
This does NOT close#116 - it fixes a tangential constant, not either
reported shape. Ghidra also settled the two shapes' diagnosis (recorded
in ISSUES.md #116 + physics digest):
- Shape-1: our cn=UnitZ default IS retail-faithful (validate_transition
0x0050aa70 has the identical `if (collision_normal_valid==0)
set_collision_normal(UnitZ)`). The real divergence is upstream -
tick-22760 our collision_normal_valid was false where retail's was
true (it recorded the door-face normal). Needs the instrumented
tick-22760 replay.
- Shape-2 (D4 stays skipped, note sharpened): slide_sphere slides
in-frame (SLID_TS) so Z=1.92 is faithful and the D4 Z=2.0 hard-stop
pin is the suspect half; the threshold fix didn't move D4 (real slide,
not degenerate). Needs a cdb trace of an airborne wall hit.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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