findInterpIdx now returns {idx0, idx1, t} as a struct instead of writing
all three to the output buffer. Only output[0] is written for next-frame
cache persistence. All 29 call sites updated to use returned values.
3574 cycles (-14% vs 4176 baseline), was 3841 (-8%). Parity PASS.
Replaced all remaining game function calls:
- findInterpIdx (0x713D50): full temporal-coherence search reimplementation
- interpAnimKF in boneKeyframeLoop: reuses existing pure Zig version
- applyTranslation/rotateByQuaternion/scaleMatrix3x3 in boneKeyframeLoop
- getInterpolatedFloat (0x71AF20): replaced with interpFloatTrack (identical)
- extractByte (0x71AE90): findInterpIdx + direct byte read
- Child recursion: direct call to transformImpl_SSE instead of 0x714260 hook
Only 2 game calls remain (cannot be replaced):
- 0x409AEF: one-time atexit registration in boneKeyframeLoop
- 0x7B5F60: IsParticleBufferEmpty (reads game particle state)
Root cause of billboard visual artifacts: callVec3SqMag used inline asm
to call game's x87 vec3SqMag (0x4549F0) with fstps to capture ST0.
With SSE2 codegen, the x87/SSE state interaction caused corrupted float
values in billboard bone matrices (mat[0][2] wildly wrong).
Replaced with pure Zig: x*x + y*y + z*z — no x87, no inline asm.
Also replaced:
- matMul (0x74A7C0): pure Zig f64 scalar matmul, no alignment needs
- callFtol (0x40A2B0): f64 intermediate + @intFromFloat (cvttsd2si)
Architecture: bone_sse.zig is REF code compiled with SSE2, called as
cdecl from thiscall wrapper in transform44.zig (cross-object to prevent
LLVM inlining AND ESP alignment into thiscall frame).
A/B: other hooks gated behind AB_OTHER_HOOKS=false for isolated testing.
Assembly-verified fixes from t44_helpers_asm.txt:
findInterpIdx (0x713D50):
- Range format is [start, last] not [start, count] (DEC EDI pattern)
- Backward scan entry: delta >= 0xFFFFFE0C not > (JC = unsigned below)
- 500-tick threshold (0x1F4) for forward/backward vs binary search
- GS check is CMP AX,0xFFFF (word compare), not >= 0
- t computation: FILD qword (i64 numer) / FIDIV dword (i32 denom)
interpAnimKF (0x713EA0):
- Keyframe stride is 16 bytes (SHL EAX,0x4), NOT 8 (CompQuat)
- Values are raw floats, no short-to-float conversion needed
Runtime constants — all now read from game memory:
- 0x80297C (3.0) and 0x802990 (6.0) for Hermite/Bezier basis
- 0x80C5C8 for billboard squared magnitude threshold
- 0x811610 and 0x8029D4 already read at runtime
Wrapper pattern: thiscall export delegates to normal fn for AVX alignment.
Full 5317-instruction walkthrough of t44_full_asm.txt vs bone_sse_reference.zig.
Crash fix (Issues 1-2): When anim_start >= anim_end in the looping animation
path, assembly always writes prim_time/sec_time = anim_start as fallback.
REF skipped the write, leaving garbage in bone_rt timing fields. On newly
loaded world SceneObjects this propagated through findInterpIdx → extractByte
→ ACCESS_VIOLATION at 0x71AEBC with ECX=0x7FFFFFFF (self-reinforcing bad
cached index).
Time clamp fix (Issues 3-4): Clamped-not-passed animation path now clamps
cur_time to sec_start when sec_start > cur_time, matching assembly at
0x7145EB/0x71474B.
Crossfade fix (Issues 5-6): interpVec3Track36 and interpFloatTrack12 had
'else return' for unknown interp modes. Assembly's JNZ skips primary interp
but falls through to crossfade check. Changed to 'else {}' fallthrough.
Also includes prior uncommitted fixes: particle crossfade blend_weight
restoration, bw>0→bw!=0, attach_count==0 early-return removal.
Bug #15: Short-value interpolation read AD+0x0C (nTimestamps count) as
pointer to short array. Should be AD+0x18 (ofsValues). Caused segfault
reading from address ~0x134 (a count value treated as pointer).
Bug #16: boneKeyframeLoop AnimData offsets wrong. Rotation was kf_data+0x10,
should be +0x1C. Scale was kf_data+0x28 with garbled gate, should be +0x38
with gate at +0x44. Translation was correct at +0x00. Entry structure is
3x28-byte AnimBlocks: trans(+0x00), rot(+0x1C), scale(+0x38) = stride 0x54.
Bug #17: particleEmitterLoop (model_hdr+0x124) position AnimData was
entry+0x04, should be entry+0x10 with gate at entry+0x1C. Second track
was entry+0x20, should be entry+0x38/gate +0x44. Third track at
entry+0x60/gate +0x6C was missing entirely.
Also fixed IsParticleBufferEmpty calling convention (bug #14):
was __stdcall with stack param, now __fastcall(ECX=ptr) plain RET.
SSE dispatch enabled for A/B testing.
Was __stdcall with stack param — would corrupt stack for every visible
particle emitter. Fixed to __fastcall(ECX=ptr) matching assembly at
0x717EB8: MOV ECX,[EBP-0x10]; CALL 0x7B5F60. Plain RET, no stack cleanup.
Bug #14 found during final verification pass.
bone_sse.zig: Full standalone SSE reimplementation of the 17703-byte bone
transform engine (0x714260). All helper functions reimplemented inline
(findInterpolationIndices, interpolateAnimationKeyframes, scaleMatrix3x3,
ApplyTranslation, rotateByQuaternion). Currently disabled (A/B dispatch
commented out) due to NULL ofsValues crash under investigation.
transform44.zig: Add OnWorldUpdate (0x482EA0) hook for true per-frame
counting. Previous frame counter used executeSceneRenderPass which fires
multiple times per frame (shadows, reflections, spell effects), causing
A/B periods to be as short as 0.5s during combat instead of ~30s.
SCENEOBJECT_OFFSETS.md: Complete assembly-verified field offset map
(51 offsets) extracted from [EBX+N] patterns in transformMatrix4x4.
Corrects bone_runtime_base from +0x80 to +0x090.
MarcelineVQ