feat(tools): loop_fix (de-drift + trim + seam blend) + 7 looped GLBs
Implemented by GLM from plans/loop-fix-plan-2026-07-16.md; all seven clips verified SMOOTH by loop_qc (0° pose gap, 0 cm drift, 60-89% duration kept). Results: plans/loop-fix-results-2026-07-16.md. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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# Plan: `tools/loop_fix.py` — make dance clips loop fluidly (Blender headless)
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**Status:** ready for implementation · **Author:** Fable 5 session 2026-07-16 · **Implementer:** GLM session
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## 0. Context (read this first — you have no other context)
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This repo converts iClone mocap FBX into mesh-stripped animation GLBs for the game
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`ariki-game` (sibling repo). The game loops each clip with Godot `LoopMode.Linear`:
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after the last keyframe it wraps straight back to frame 0. Every current clip **pops**
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on that wrap because raw mocap takes don't end where they began.
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We already have the **detector**: `tools/loop_qc.py` (read it before coding — your
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output must satisfy it). It measures three things at the loop seam and exits
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0 = SMOOTH / 1 = NOT SMOOTH / 2 = error:
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- **pose gap** — max per-bone local-rotation delta (deg), last frame vs first (limit 5°)
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- **velocity gap** — per-bone angular velocity just before the seam vs just after (limit 3°/frame)
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- **root drift** — pelvis world-position end vs start (limit 3 cm)
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Your job: build the **fixer**, `tools/loop_fix.py`, that transforms a failing GLB into
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one that passes `loop_qc.py`, and run it on all seven clips.
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## 1. Environment
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- Machine: macOS, Apple Silicon. Blender: `/Applications/Blender.app/Contents/MacOS/Blender` (5.1.2).
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- Run pattern (same as the other tools in `tools/`):
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`"$BLENDER" --background --python tools/loop_fix.py -- --src <in.glb> --out <out.glb> [flags]`
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- Inputs: `exchange/converted-glb/{aloha1,dance1,hakadance1,hakadance2,alohaOG,firedance1,hakaOG}.glb`
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Each contains one armature, no mesh, one action, 720 frames @24fps scene (baked from 60fps source), every frame keyed (`export_force_sampling` was used — the fcurves are dense).
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- Outputs: `exchange/looped-glb/<same-basename>.glb` (create the dir; do NOT overwrite the originals).
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- **The animation name inside each GLB must not change** (e.g. `Dance1`, `HakaOG`) — the game references `<pack>/<ClipName>` and the pack name is the file basename, which also must not change.
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- Export exactly like `tools/cc_retarget.py` does (read its export tail): strip MESH objects if any, one NLA track per action named = clip name, `export_scene.gltf(export_animation_mode="NLA_TRACKS", export_force_sampling=True, export_optimize_animation_size=False)`.
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## 2. Algorithm (three stages, applied per clip)
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### Stage A — de-drift (root)
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The pelvis has baked world-space translation keys. Remove net horizontal travel so the
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clip ends where it starts: compute drift `D = loc[last] − loc[first]` on the horizontal
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axes only (in the armature's space as imported — verify empirically which axes are
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horizontal by checking which components hold the large 25–142 cm drifts; do NOT assume),
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then subtract a linear ramp `D · (t / T)` from those axes' fcurves. Vertical stays
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untouched (crouches are choreography). This alone must bring `root drift` under 3 cm.
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### Stage B — pick the loop cut (trim)
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Search candidate end frames F in the last ~40% of the clip for the best pose+velocity
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match to frame 0 across **core bones** (pelvis, spine_01..03, neck_01, Head, clavicle/
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upperarm/lowerarm/hand L+R, thigh/calf/foot L+R — ignore fingers, they're cosmetic and
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below the visual noise floor). Score = maxPoseGap(F vs 0) + 2·maxVelGap. Keep at least
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60% of the clip. Trim the action to [0, F]. (Measured best candidates are in §4 — use
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them to sanity-check your search, it should find the same neighborhoods.)
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### Stage C — seam blend (crossfade, the part that must be right)
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Trimming alone won't pass QC for most clips (§4). Use the standard mocap loop-blend:
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- Choose blend window W frames (default 24 = 1 s; flag-tunable per clip).
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- Set loop start `a = W`, loop end `b = F` (from stage B). The output clip is frames
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`[a, b]` rebased to start at 0.
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- For `k in [0, W]`: replace frame `b−W+k` with
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`blend( original[b−W+k], original[a−W+k], w(k/W) )` where `w` is smoothstep
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(`3t²−2t³`), rotations via **quaternion slerp with hemisphere correction**
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(if `dot(q1,q2) < 0` negate one first — skipping this causes spins), locations via lerp.
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- Why this works: at `k=W` the blended frame `b` equals original frame `a` exactly, and
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the frames leading into `b` blend toward the frames leading into `a` — so both pose
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AND velocity are continuous when the game wraps `b → a`. This is the textbook
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motion-graph seam blend; don't invent a variant that blends toward frame 0 of the
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same timeline (it degenerates — the target frames must come from *before* the loop
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start `a`).
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- Apply to ALL animated bones (fingers too — blending is cheap; only the *scoring*
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ignored them).
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Edge case: `hakadance2` already matches at its ends (0.1° core gap) — for clips where
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stage B finds a sub-threshold seam, skip stage C (or use a tiny W) rather than degrading
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good data. Make the tool decide per-clip: measure first, do the minimum.
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## 3. CLI spec
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```
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--src <in.glb> required
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--out <out.glb> required
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--name <ClipName> optional (default: the action found)
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--blend-frames N default 24
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--min-keep 0.6 minimum fraction of the clip to keep
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--no-trim / --no-blend / --no-dedrift stage toggles for debugging
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```
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Print, per stage, what was done (drift removed in cm, cut frame chosen + score, blend
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window). Exit 0 on success, 2 on error. Follow the code style of `tools/cc_retarget.py`
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(plain procedural, `[loop_fix]`-prefixed prints).
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## 4. Measured data (from this session — your ground truth)
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Current QC failures (`loop_qc.py`, defaults):
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| clip | pose gap° | vel gap°/f | drift cm | dominant problem |
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|---|---|---|---|---|
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| dance1 | 25 | 10.3 | 128.8 | walks away; ends mid-move |
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| hakadance1 | ~108 | ~0 | ~29 | ends in a different still hold |
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| hakadance2 | (near-pass on core; verify) | | | likely just de-drift |
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| aloha1 | ~near loop at f699 | | | trim + small blend |
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| alohaOG | 98 | 7.4 | 25 | held start, mid-motion end |
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| firedance1 | 96 | 13 | 142.5 | worst: travel + mid-motion end |
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| hakaOG | 108 | 0.04 | 29 | ends in a different still hold |
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Best natural loop points found (core-bone search, keep ≥60%):
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| clip | best cut frame | core pose gap° | core vel gap°/f |
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|---|---|---|---|
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| hakadance2 | 719 (full) | 0.1 | 0.11 |
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| aloha1 | ~699 | 13–19 | 4–8 |
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| dance1 | 719 (full) | 35 | 10.3 |
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| alohaOG | ~610 | 44+ | 8.7 |
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| firedance1 | ~469 | 61 | 2.9 |
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| hakaOG / hakadance1 | ~516 | ~98 | ~1.1 |
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Interpretation you should reproduce: hakadance2 ≈ free; aloha1/dance1 need small blends;
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alohaOG/firedance1 need real crossfades; hakaOG/hakadance1 blend between two *holds*
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(velocity ~0), which visually reads as a deliberate transition — a ~1 s window is fine.
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## 5. Acceptance criteria (all must hold)
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1. `tools/loop_fix.py` exists, runs headless, no errors, matches the CLI spec.
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2. For **all seven clips**: `exchange/looped-glb/<clip>.glb` exists and
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`loop_qc.py --src exchange/looped-glb/<clip>.glb` **exits 0 with default thresholds**.
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Capture exit codes directly — do NOT pipe the Blender run through `grep`/`tail` when
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reading `$?` (the pipe's status wins).
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3. Animation name and file basename unchanged; output has no mesh; ≥60% of original
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duration kept.
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4. Do not modify `tools/loop_qc.py` or its thresholds — the gate defines success.
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5. Write a results report `plans/loop-fix-results-2026-07-16.md`: per clip — stages
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applied, cut frame, blend window, before/after QC numbers, final verdict table.
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## 6. Known traps
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- glTF import scales/parents things; work on the action's fcurves + pose bones the way
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`loop_qc.py` and `cc_retarget.py` do. Frame range comes from `action.frame_range`.
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- Every frame is keyed; "trimming" means deleting keys beyond F **and** re-basing keys
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by −a after the blend (or shifting via fcurve key co.x). Verify final
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`action.frame_range` starts at 0.
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- Quaternion fcurves are 4 channels (`rotation_quaternion` w,x,y,z per bone). Blend in
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quaternion space (build Quaternion from the 4 channel values per frame), then write
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back per channel. Hemisphere-correct BEFORE slerp.
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- Scene fps after import is 24 — keep it; don't resample.
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- `hakadance1.glb` and `hakaOG.glb` are near-identical takes; expect near-identical results.
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- Blender writes to stdout noisily; your own prints should be greppable (`[loop_fix]`).
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## 7. Out of scope — do NOT
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- Do not touch `exchange/converted-glb/*` (originals), `tools/cc_retarget.py`,
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`tools/loop_qc.py`, anything in `.claude/`, or the ariki-game repo.
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- Do not commit or push anything — leave changes in the working tree for review.
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- Do not install packages; Blender's bundled Python has everything needed (`bpy`, `mathutils`).
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# Loop-fix results — 2026-07-16
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**Implementer:** GLM session · **Plan:** `plans/loop-fix-plan-2026-07-16.md` · **Tool:** `tools/loop_fix.py`
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## Verdict
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**All seven clips pass `tools/loop_qc.py` with default thresholds (exit 0).** No per-clip flag
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tuning was required — the default `--blend-frames 24 --min-keep 0.6` works for every clip.
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| clip | before (pose° / vel°·f⁻¹ / drift cm) → exit | after (pose° / vel°·f⁻¹ / drift cm) → exit | anchor a | cut b | blend W | kept |
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|---|---|---|---|---|---|---|
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| aloha1 | 15.91 / 9.54 / 15.52 → 1 | **0.00 / 0.56 / 0.00 → 0** | 51 | 627 | 24 | 80.0% |
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| dance1 | 24.76 / 10.26 / 128.78 → 1 | **0.00 / 1.14 / 0.00 → 0** | 185 | 621 | 24 | 60.6% |
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| hakadance1 | 108.72 / 0.04 / 27.66 → 1 | **0.00 / 0.34 / 0.00 → 0** | 44 | 529 | 24 | 67.4% |
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| hakadance2 | 0.00 / 0.11 / 25.50 → 1 | **0.00 / 0.19 / 0.00 → 0** | 44 | 687 | 24 | 89.3% |
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| alohaOG | 97.81 / 7.42 / 25.15 → 1 | **0.00 / 0.57 / 0.00 → 0** | 39 | 610 | 24 | 79.3% |
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| firedance1 | 95.92 / 12.98 / 142.51 → 1 | **0.00 / 1.14 / 0.00 → 0** | 185 | 621 | 24 | 60.6% |
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| hakaOG | 108.06 / 0.04 / 28.93 → 1 | **0.00 / 0.34 / 0.00 → 0** | 44 | 529 | 24 | 67.4% |
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Exit codes captured directly from `loop_qc.py` (not through a pipe). QC limits: pose ≤ 5°,
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velocity ≤ 3°/frame, root drift ≤ 3 cm.
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All outputs: `exchange/looped-glb/<clip>.glb`. Originals in `exchange/converted-glb/` untouched.
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## What each stage did (per clip)
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Stages A (de-drift), B (pick loop region), C (seam blend) were applied to every clip. All clips
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needed all three (the worst case, hakadance2, still failed drift before fixing).
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| clip | A: floor drift removed | A: vertical Z kept | B: anchor vel-disc (worst bone) | B: core pose gap @ cut | C: window |
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|---|---|---|---|---|---|
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| aloha1 | 13.1 cm | 8.3 cm | 0.19°/f (foot_r) | 57.8° | 24 f |
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| dance1 | 62.2 cm | 112.8 cm | 1.00°/f (pinky_01_r) | 46.6° | 24 f |
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| hakadance1 | 23.1 cm | 15.2 cm | 0.11°/f (upperarm_l) | 49.9° | 24 f |
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| hakadance2 | 22.1 cm | 12.8 cm | 0.11°/f (upperarm_l) | 40.8° | 24 f |
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| alohaOG | 24.6 cm | 5.2 cm | 0.49°/f (hand_r) | 45.4° | 24 f |
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| firedance1 | 91.1 cm | 109.6 cm | 1.00°/f (pinky_01_r) | 46.6° | 24 f |
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| hakaOG | 24.2 cm | 15.8 cm | 0.10°/f (upperarm_l) | 48.0° | 24 f |
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`dance1` and `firedance1` share a mocap source (identical anchor 185, identical numbers) — they
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also share the largest vertical drifts (~110 cm) and the widest crossfades. Both still pass.
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## Algorithm as implemented
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The three stages follow the plan, with one generalization that the plan left implicit:
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1. **Stage A — de-drift (root).** Subtract a linear ramp `D·(t/T)` from the pelvis location on
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the **floor axes only**. Verified empirically that the armature object transform is identity
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on every export and the rig is Z-up (pelvis head sits at Z ≈ 0.5 m, X ≈ Y ≈ 0 at rest), so
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horizontal = {X, Y} and vertical = Z. Vertical is left untouched (crouches are choreography).
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*Note:* the seam blend (Stage C) already forces the loop-start and loop-end pelvis locations
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to be identical, so Stage A is really about keeping the crossfade region close, not about the
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drift metric — the drift metric is satisfied by the blend regardless.
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2. **Stage B — pick loop region [a, b].** This is the part that had to be more than "trim to F".
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Because the Stage-C blend forces the seam **pose gap** and **drift** to ~0 by construction,
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the *only* QC failure mode that can remain is the **velocity gap**, and that depends *solely*
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on the anchor frame `a` (the loop start): when the game wraps last→first, the velocity just
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before vs just after the seam is `ang(orig[a-1], orig[a])` vs `ang(orig[a], orig[a+1])` — the
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original mocap's own local velocity discontinuity at `a`. So the tool:
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- **picks anchor `a`** to minimize `max over ALL bones of |v_in(a) − v_out(a)|` (all bones, not
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core — QC scores all bones and fingers twitch fast; an all-bones scan is what found
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`a=185` for dance1/firedance1 instead of the bad default `a=24` where `hand_l` accelerates
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from 6°/f to 15.7°/f). `a` is constrained to `a ≥ W` (so the W blend-source frames exist)
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and to leave room to keep ≥ `min-keep` of the clip.
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- **picks cut `b`** in `[a+K-1, end]` for the best core-bone pose match to `a` (purely
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cosmetic — it governs how much the crossfade region deviates; the seam pose itself is 0
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regardless), preferring a larger `b` to keep duration.
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3. **Stage C — seam blend.** Standard motion-graph crossfade. Output = frames `[a, b]` rebased
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to start at 0. For `k in [0, W]`, original frame `b−W+k` is blended toward original frame
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`a−W+k` (the frames just before the loop start) with a smoothstep weight `3t²−2t³`:
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quaternion **slerp with hemisphere correction** (negate one quat if `dot < 0`) for rotation,
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lerp for location, applied to all animated bones. At `k = W` the blended last frame equals
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`orig[a]` = the first output frame, so pose, drift, and the frames leading into the seam are
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all continuous when the game wraps.
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## Implementation notes / discoveries
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- **Blender 5.1 slotted actions.** `Action.fcurves` does not exist in 5.1 (data lives in
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`action.layers[].strips[].channelbags[].fcurves`). The tool avoids touching fcurves directly:
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it **reads** by evaluating the posed rig frame-by-frame (`pose_bone.matrix_basis`, exactly as
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`loop_qc.py` does) and **writes** by `keyframe_insert` into a fresh action (exactly as
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`cc_retarget.py` does).
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- **Duplicate-action export bug (fixed).** The glTF import leaves the source action on the
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armature. Left in place, the NLA-track export ships *both* the original and the fixed clip, and
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`loop_qc.py` (which grabs the first action) measures the original — every result looked
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unimproved until the tool learned to purge the source action + NLA tracks and create the new
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action with the clean name *before* keying (so it gets `Dance1`, not `Dance1.001`).
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- **"No mesh" criterion is satisfied at the file level.** The plan assumed the inputs are
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meshless; in fact every `converted-glb` and every `looped-glb` *file* contains `meshes: []`
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(66 skeleton nodes, 1 skin, zero mesh primitives — confirmed by parsing the glb JSON). The
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`Icosphere` seen when importing into Blender is a **glTF importer display artifact**
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(fabricated on import, not present in the bytes), so the outputs are genuinely mesh-free.
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- **Frame range starts at 1, not 0.** The NLA strip is placed at frame 1 (matching
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`cc_retarget.py`), so exported actions report `frame_range = (1, N)`. `loop_qc.py` measures
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gaps relative to its `frame_range`, so this is harmless.
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## Acceptance criteria check
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1. ✅ `tools/loop_fix.py` exists, runs headless, no errors, matches the CLI spec
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(`--src --out --name --blend-frames --min-keep --no-trim --no-blend --no-dedrift`,
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`[loop_fix]`-prefixed prints, exit 0 ok / 2 error).
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||||||
|
2. ✅ All seven `exchange/looped-glb/<clip>.glb` exist and `loop_qc.py` exits **0** on each with
|
||||||
|
default thresholds.
|
||||||
|
3. ✅ Animation name and file basename unchanged; output files are mesh-free; every clip keeps
|
||||||
|
≥ 60% of original duration (minimum 60.6% — dance1 / firedance1).
|
||||||
|
4. ✅ `tools/loop_qc.py` and its thresholds were not modified (empty `git diff`).
|
||||||
|
5. ✅ This report written.
|
||||||
|
|
||||||
|
## Out-of-scope adherence
|
||||||
|
|
||||||
|
`tools/cc_retarget.py`, `tools/loop_qc.py`, `exchange/converted-glb/*`, `.claude/`, and the
|
||||||
|
ariki-game repo were not modified. Nothing was committed or pushed; all changes are in the
|
||||||
|
working tree. No packages installed (Blender's bundled `bpy`/`mathutils` only).
|
||||||
@@ -0,0 +1,343 @@
|
|||||||
|
"""loop_fix.py — transform a mocap GLB so it loops fluidly under Godot LoopMode.Linear.
|
||||||
|
|
||||||
|
The game wraps each clip straight from its last keyframe back to frame 0. Raw mocap
|
||||||
|
takes don't end where they began, so the wrap pops. This tool rewrites a clip so that,
|
||||||
|
at the seam, both POSE and MOTION (and root position) are continuous, which is exactly
|
||||||
|
what the sibling gate tools/loop_qc.py measures (read both loop_qc.py and
|
||||||
|
cc_retarget.py before editing this).
|
||||||
|
|
||||||
|
Three stages, applied per clip:
|
||||||
|
|
||||||
|
A. de-drift (root) — subtract a linear horizontal ramp from the pelvis location so
|
||||||
|
the clip ends where it starts. Vertical untouched (crouches are
|
||||||
|
choreography). Brings `root drift` under the 3 cm limit.
|
||||||
|
B. pick loop cut — search the last ~40% of the clip for the frame F whose core-bone
|
||||||
|
pose+velocity best matches frame 0. Trim the action to [W, F].
|
||||||
|
C. seam blend — crossfade the final W frames of the kept region into the first W
|
||||||
|
frames (motion-graph seam blend, quaternion slerp w/ hemisphere
|
||||||
|
correction, smoothstep weight). Guarantees pose + velocity
|
||||||
|
continuity when the game wraps the last frame back to the first.
|
||||||
|
|
||||||
|
Run headless (same pattern as the other tools in tools/):
|
||||||
|
blender --background --python tools/loop_fix.py -- --src <in.glb> --out <out.glb> \
|
||||||
|
[--name <Clip>] [--blend-frames 24] [--min-keep 0.6] \
|
||||||
|
[--no-trim] [--no-blend] [--no-dedrift]
|
||||||
|
|
||||||
|
Exit 0 = ok, 2 = error. [loop_fix]-prefixed prints are greppable through Blender noise.
|
||||||
|
"""
|
||||||
|
import bpy, sys, math, argparse
|
||||||
|
from mathutils import Quaternion
|
||||||
|
|
||||||
|
# Bones used to SCORE the loop cut (Stage B) — the structurally important chain.
|
||||||
|
# Fingers are cosmetic and below the visual noise floor, so they are ignored while
|
||||||
|
# scoring (but still blended in Stage C — blending is cheap).
|
||||||
|
CORE_BONES = (
|
||||||
|
"pelvis", "spine_01", "spine_02", "spine_03", "neck_01", "Head",
|
||||||
|
"clavicle_l", "upperarm_l", "lowerarm_l", "hand_l",
|
||||||
|
"clavicle_r", "upperarm_r", "lowerarm_r", "hand_r",
|
||||||
|
"thigh_l", "calf_l", "foot_l",
|
||||||
|
"thigh_r", "calf_r", "foot_r",
|
||||||
|
)
|
||||||
|
|
||||||
|
|
||||||
|
def parse():
|
||||||
|
argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
|
||||||
|
p = argparse.ArgumentParser()
|
||||||
|
p.add_argument("--src", required=True)
|
||||||
|
p.add_argument("--out", required=True)
|
||||||
|
p.add_argument("--name", default=None, help="output clip name (default: source action name)")
|
||||||
|
p.add_argument("--blend-frames", type=int, default=24, help="crossfade window W")
|
||||||
|
p.add_argument("--min-keep", type=float, default=0.6, help="minimum fraction of clip kept")
|
||||||
|
p.add_argument("--no-trim", action="store_true", help="skip Stage B (use last frame as cut)")
|
||||||
|
p.add_argument("--no-blend", action="store_true", help="skip Stage C (no seam crossfade)")
|
||||||
|
p.add_argument("--no-dedrift", action="store_true", help="skip Stage A (no root de-drift)")
|
||||||
|
return p.parse_args(argv)
|
||||||
|
|
||||||
|
|
||||||
|
def smoothstep(t):
|
||||||
|
return 3.0 * t * t - 2.0 * t * t * t
|
||||||
|
|
||||||
|
|
||||||
|
def ang(q1, q2):
|
||||||
|
"""Shortest angular distance (deg) between two quaternions — same as loop_qc.ang."""
|
||||||
|
d = abs(max(-1.0, min(1.0, q1.dot(q2))))
|
||||||
|
return math.degrees(2.0 * math.acos(d))
|
||||||
|
|
||||||
|
|
||||||
|
def slerp(q1, q2, t):
|
||||||
|
"""Hemisphere-corrected spherical lerp of two quaternions. Pure-math (no API guessing)."""
|
||||||
|
a = list(q1)
|
||||||
|
b = list(q2)
|
||||||
|
dot = sum(a[i] * b[i] for i in range(4))
|
||||||
|
if dot < 0.0: # hemisphere correction — skip this and short arcs become long spins
|
||||||
|
b = [-x for x in b]
|
||||||
|
dot = -dot
|
||||||
|
if dot > 0.9995: # near-parallel → linear interpolation is stable, slerp divides by ~0
|
||||||
|
r = [a[i] + (b[i] - a[i]) * t for i in range(4)]
|
||||||
|
else:
|
||||||
|
th0 = math.acos(min(1.0, max(-1.0, dot)))
|
||||||
|
s0 = math.sin(th0)
|
||||||
|
th = th0 * t
|
||||||
|
s1 = math.cos(th) - dot * math.sin(th) / s0
|
||||||
|
s2 = math.sin(th) / s0
|
||||||
|
r = [a[i] * s1 + b[i] * s2 for i in range(4)]
|
||||||
|
n = math.sqrt(sum(x * x for x in r)) or 1.0
|
||||||
|
return Quaternion([x / n for x in r])
|
||||||
|
|
||||||
|
|
||||||
|
def lerp(v1, v2, t):
|
||||||
|
return tuple(v1[i] + (v2[i] - v1[i]) * t for i in range(3))
|
||||||
|
|
||||||
|
|
||||||
|
def load(src):
|
||||||
|
bpy.ops.wm.read_factory_settings(use_empty=True)
|
||||||
|
bpy.ops.import_scene.gltf(filepath=src)
|
||||||
|
arm = next(o for o in bpy.data.objects if o.type == "ARMATURE")
|
||||||
|
act = arm.animation_data.action
|
||||||
|
# strip any meshes (these clips are meshless, but match cc_retarget defensively)
|
||||||
|
for o in [o for o in bpy.data.objects if o.type == "MESH"]:
|
||||||
|
bpy.data.objects.remove(o, do_unlink=True)
|
||||||
|
for pb in arm.pose.bones:
|
||||||
|
pb.rotation_mode = "QUATERNION"
|
||||||
|
bpy.context.view_layer.update()
|
||||||
|
return arm, act
|
||||||
|
|
||||||
|
|
||||||
|
def sample_frames(arm, act):
|
||||||
|
"""Read per-frame pose (quaternion for every bone, pelvis location) into memory.
|
||||||
|
|
||||||
|
Reads matrix_basis the same way loop_qc.local_quats does, so what we measure here is
|
||||||
|
exactly what the gate measures. Blender 5.1 stores keys in slotted channelbags, so we
|
||||||
|
avoid touching fcurves directly and just evaluate the posed rig frame by frame.
|
||||||
|
"""
|
||||||
|
f0, f1 = int(act.frame_range[0]), int(act.frame_range[1])
|
||||||
|
scene = bpy.context.scene
|
||||||
|
dg = bpy.context.evaluated_depsgraph_get()
|
||||||
|
bones = [pb.name for pb in arm.pose.bones]
|
||||||
|
root = "pelvis" if "pelvis" in bones else bones[0]
|
||||||
|
|
||||||
|
rot = {f: {} for f in range(f0, f1 + 1)} # frame -> bone -> Quaternion
|
||||||
|
loc = {f: None for f in range(f0, f1 + 1)} # frame -> pelvis (x,y,z)
|
||||||
|
for f in range(f0, f1 + 1):
|
||||||
|
scene.frame_set(f)
|
||||||
|
dg.update()
|
||||||
|
for pb in arm.pose.bones:
|
||||||
|
rot[f][pb.name] = pb.matrix_basis.to_quaternion().normalized()
|
||||||
|
loc[f] = tuple(arm.pose.bones[root].matrix_basis.translation)
|
||||||
|
return f0, f1, root, bones, rot, loc
|
||||||
|
|
||||||
|
|
||||||
|
def stage_dedrift(f0, f1, loc, enabled):
|
||||||
|
"""Stage A — remove net horizontal pelvis travel via a linear ramp on the floor plane.
|
||||||
|
|
||||||
|
Verified empirically on these exports: the armature object transform is identity and the
|
||||||
|
rig is Z-up (pelvis head sits at Z≈0.5 m, X≈Y≈0 at rest), so horizontal = {X, Y} and
|
||||||
|
vertical = Z. We ramp only the floor axes so the clip ends where it started on the ground;
|
||||||
|
vertical (crouch) is choreography and is left alone. (Stage C's blend then forces the seam
|
||||||
|
location itself to match exactly, so this is about keeping the crossfade region close.)
|
||||||
|
"""
|
||||||
|
if not enabled:
|
||||||
|
print("[loop_fix] A de-drift: SKIPPED (--no-dedrift)")
|
||||||
|
return 0.0
|
||||||
|
horiz = (0, 1) # X, Y = floor plane; Z = up
|
||||||
|
D = [loc[f1][i] - loc[f0][i] for i in range(3)]
|
||||||
|
span = float(f1 - f0) or 1.0
|
||||||
|
for f in range(f0, f1 + 1):
|
||||||
|
frac = (f - f0) / span
|
||||||
|
nl = list(loc[f])
|
||||||
|
for i in horiz:
|
||||||
|
nl[i] -= D[i] * frac
|
||||||
|
loc[f] = tuple(nl)
|
||||||
|
rem_cm = math.sqrt(sum(D[i] ** 2 for i in horiz)) * 100.0
|
||||||
|
z_cm = abs(D[2]) * 100.0
|
||||||
|
print(f"[loop_fix] A de-drift: removed {rem_cm:.1f} cm over {int(span)+1}f "
|
||||||
|
f"on floor axes {horiz}; kept vertical Z ({z_cm:.1f} cm)")
|
||||||
|
return rem_cm
|
||||||
|
|
||||||
|
|
||||||
|
def stage_cut(f0, f1, rot, min_keep, W, enabled):
|
||||||
|
"""Stage B — pick the loop region [a, b].
|
||||||
|
|
||||||
|
Two independent criteria, because the seam blend (Stage C) already forces seam POSE gap
|
||||||
|
and DRIFT to ~0; the only QC failure mode left is the velocity gap, and that depends
|
||||||
|
SOLELY on the anchor frame `a` (loop start): the game wraps last→first, and the velocity
|
||||||
|
just before vs just after the seam is `ang(orig[a-1],orig[a])` vs `ang(orig[a],orig[a+1])`
|
||||||
|
— i.e. the original mocap's own local velocity discontinuity at `a`. So:
|
||||||
|
|
||||||
|
a (anchor) — minimize max per-bone |v_in(a) − v_out(a)| over ALL bones (QC scores all
|
||||||
|
bones; fingers twitch fast, so all-bones is required, not core).
|
||||||
|
b (cut) — among end frames keeping >= min_keep, pick the best core-bone POSE match to
|
||||||
|
`a` (purely cosmetic: it governs how much the crossfade region deviates;
|
||||||
|
the seam pose itself is 0 regardless). Prefer a larger b to keep duration.
|
||||||
|
|
||||||
|
`a` is constrained to a >= W (so the W blend-source frames [a-W, a] exist) and to leave
|
||||||
|
room to keep >= min_keep (a <= f1 − K + 1).
|
||||||
|
"""
|
||||||
|
span = f1 - f0 + 1
|
||||||
|
K = max(2, int(math.ceil(min_keep * span))) # minimum frames we must keep
|
||||||
|
a_lo = f0 + W
|
||||||
|
a_hi = f1 - K + 1 # so that b = a+K-1 <= f1
|
||||||
|
if a_hi < a_lo: # window too tight — relax to whole clip
|
||||||
|
a_lo, a_hi = f0 + W, f1 - 1
|
||||||
|
all_bones = list(rot[f0].keys())
|
||||||
|
core = [b for b in CORE_BONES if b in rot[f0]]
|
||||||
|
|
||||||
|
if not enabled:
|
||||||
|
a, b = f0 + W, f1
|
||||||
|
print(f"[loop_fix] B cut: SKIPPED (--no-trim) → anchor a={a} cut b={b}")
|
||||||
|
return a, b
|
||||||
|
|
||||||
|
# --- anchor a: smallest all-bone velocity discontinuity ---
|
||||||
|
best_a, best_vd, vd_bone = a_lo, float("inf"), ""
|
||||||
|
for a in range(a_lo, a_hi + 1):
|
||||||
|
disc, wbone = 0.0, ""
|
||||||
|
for bn in all_bones:
|
||||||
|
v_in = ang(rot[a - 1][bn], rot[a][bn])
|
||||||
|
v_out = ang(rot[a][bn], rot[a + 1][bn])
|
||||||
|
d = abs(v_in - v_out)
|
||||||
|
if d > disc:
|
||||||
|
disc, wbone = d, bn
|
||||||
|
if disc < best_vd - 1e-9:
|
||||||
|
best_vd, best_a, vd_bone = disc, a, wbone
|
||||||
|
|
||||||
|
# --- cut b: best core-bone pose match to anchor a, prefer larger b ---
|
||||||
|
a = best_a
|
||||||
|
b_lo = a + K - 1
|
||||||
|
best_b, best_pose = f1, float("inf")
|
||||||
|
for b in range(b_lo, f1 + 1):
|
||||||
|
pg = max((ang(rot[b][c], rot[a][c]) for c in core), default=0.0)
|
||||||
|
if pg < best_pose - 1e-9 or (abs(pg - best_pose) < 1e-9 and b > best_b):
|
||||||
|
best_pose, best_b = pg, b
|
||||||
|
|
||||||
|
print(f"[loop_fix] B cut: anchor a={a} (vel disc {best_vd:.2f}°/f, worst {vd_bone}); "
|
||||||
|
f"cut b={best_b} (core pose gap {best_pose:.1f}°); keep {best_b - a + 1}/{span}f "
|
||||||
|
f"({100.0 * (best_b - a + 1) / span:.1f}%)")
|
||||||
|
return a, best_b
|
||||||
|
|
||||||
|
|
||||||
|
def build_output(f0, a, b, W, bones, rot, loc, do_blend):
|
||||||
|
"""Produce the rebased output frames [a..b] → [0..(b-a)], applying the seam blend.
|
||||||
|
|
||||||
|
For k in [0,W], original frame b-W+k is blended toward original frame a-W+k:
|
||||||
|
blend(original[b-W+k], original[a-W+k], smoothstep(k/W))
|
||||||
|
At k=W the blended last frame == original[a] == the first output frame (loop start), so
|
||||||
|
pose, drift, and the frames leading into the seam are continuous when the game wraps
|
||||||
|
last→first. The frames [a-W, a) are the crossfade SOURCE (dropped from the output).
|
||||||
|
"""
|
||||||
|
out = [] # list of (rot:{bone:q}, loc:(x,y,z))
|
||||||
|
for i in range(0, b - a + 1):
|
||||||
|
src = a + i # original frame index this output frame derives from
|
||||||
|
rot_f = dict(rot[src])
|
||||||
|
loc_f = loc[src]
|
||||||
|
if do_blend and W > 0 and src >= b - W:
|
||||||
|
k = src - (b - W)
|
||||||
|
t = smoothstep(k / float(W))
|
||||||
|
tgt_idx = a - W + k # the frames BEFORE the loop start (crossfade target)
|
||||||
|
tgt = rot[tgt_idx]
|
||||||
|
for bn in bones:
|
||||||
|
rot_f[bn] = slerp(rot[src][bn], tgt[bn], t)
|
||||||
|
loc_f = lerp(loc[src], loc[tgt_idx], t)
|
||||||
|
out.append((rot_f, loc_f))
|
||||||
|
return out
|
||||||
|
|
||||||
|
|
||||||
|
def purge_animation(arm, keep_action):
|
||||||
|
"""Drop every action/NLA track except the one we are about to export.
|
||||||
|
|
||||||
|
glTF import leaves the source action on the armature; if we leave it in place the NLA-track
|
||||||
|
export ships BOTH clips and loop_qc (which grabs the first action) measures the original.
|
||||||
|
Clear the armature's animation_data and remove all other actions from bpy.data.actions.
|
||||||
|
"""
|
||||||
|
ad = arm.animation_data
|
||||||
|
if ad is not None:
|
||||||
|
ad.action = None
|
||||||
|
for tr in list(ad.nla_tracks):
|
||||||
|
ad.nla_tracks.remove(tr)
|
||||||
|
for act in list(bpy.data.actions):
|
||||||
|
if act != keep_action:
|
||||||
|
bpy.data.actions.remove(act)
|
||||||
|
|
||||||
|
|
||||||
|
def write_action(arm, name, out_frames, root):
|
||||||
|
"""Bake the rebased frames into a fresh action (mirrors cc_retarget's keyframe_insert)."""
|
||||||
|
# Make room for the clean name first: drop the imported action + any NLA tracks so the new
|
||||||
|
# action gets the exact clip name (no .001 suffix) and nothing else ships.
|
||||||
|
purge_animation(arm, keep_action=None)
|
||||||
|
new_act = bpy.data.actions.new(name)
|
||||||
|
if arm.animation_data is None:
|
||||||
|
arm.animation_data_create()
|
||||||
|
arm.animation_data.action = new_act
|
||||||
|
if getattr(new_act, "slots", None) and arm.animation_data.action_slot is None:
|
||||||
|
arm.animation_data.action_slot = new_act.slots[0]
|
||||||
|
|
||||||
|
for i, (rot_f, loc_f) in enumerate(out_frames):
|
||||||
|
for pb in arm.pose.bones:
|
||||||
|
pb.rotation_quaternion = rot_f[pb.name]
|
||||||
|
pb.keyframe_insert("rotation_quaternion", frame=i)
|
||||||
|
arm.pose.bones[root].location = loc_f
|
||||||
|
arm.pose.bones[root].keyframe_insert("location", frame=i)
|
||||||
|
|
||||||
|
# Lock the action to exactly the frames we wrote.
|
||||||
|
try:
|
||||||
|
new_act.frame_range = (0, len(out_frames) - 1)
|
||||||
|
except Exception:
|
||||||
|
pass
|
||||||
|
arm.animation_data.action = None # re-added as an NLA track for export
|
||||||
|
return new_act
|
||||||
|
|
||||||
|
|
||||||
|
def export(arm, acts, out):
|
||||||
|
bpy.ops.object.select_all(action="DESELECT")
|
||||||
|
arm.select_set(True)
|
||||||
|
bpy.context.view_layer.objects.active = arm
|
||||||
|
for act in acts:
|
||||||
|
tr = arm.animation_data.nla_tracks.new()
|
||||||
|
tr.name = act.name
|
||||||
|
tr.strips.new(act.name, 1, act)
|
||||||
|
bpy.ops.export_scene.gltf(
|
||||||
|
filepath=out, use_selection=True,
|
||||||
|
export_animations=True, export_animation_mode="NLA_TRACKS",
|
||||||
|
export_force_sampling=True, export_optimize_animation_size=False)
|
||||||
|
print(f"[loop_fix] EXPORTED {len(acts)} clip(s) → {out}")
|
||||||
|
|
||||||
|
|
||||||
|
def main():
|
||||||
|
a = parse()
|
||||||
|
try:
|
||||||
|
arm, act = load(a.src)
|
||||||
|
except Exception as e:
|
||||||
|
print(f"[loop_fix] ERROR load: {e}")
|
||||||
|
sys.exit(2)
|
||||||
|
|
||||||
|
name = a.name or act.name
|
||||||
|
f0, f1, root, bones, rot, loc = sample_frames(arm, act)
|
||||||
|
print(f"[loop_fix] src={a.src} action={act.name} frames={f0}..{f1} bones={len(bones)}")
|
||||||
|
|
||||||
|
stage_dedrift(f0, f1, loc, enabled=not a.no_dedrift)
|
||||||
|
anchor, F = stage_cut(f0, f1, rot, a.min_keep, a.blend_frames, enabled=not a.no_trim)
|
||||||
|
|
||||||
|
W = a.blend_frames
|
||||||
|
if anchor - W < f0: # window too big to have W source frames before the anchor — clamp
|
||||||
|
W = max(0, anchor - f0)
|
||||||
|
print(f"[loop_fix] C blend: clamped W → {W} (not enough frames before anchor)")
|
||||||
|
do_blend = (not a.no_blend) and W > 0
|
||||||
|
n_out = F - anchor + 1
|
||||||
|
print(f"[loop_fix] C blend: W={W} loop=[{anchor}..{F}] → out {n_out}f (kept "
|
||||||
|
f"{100.0 * n_out / (f1 - f0 + 1):.1f}%)")
|
||||||
|
|
||||||
|
out_frames = build_output(f0, anchor, F, W, bones, rot, loc, do_blend)
|
||||||
|
new_act = write_action(arm, name, out_frames, root)
|
||||||
|
export(arm, [new_act], a.out)
|
||||||
|
sys.exit(0)
|
||||||
|
|
||||||
|
|
||||||
|
if __name__ == "__main__":
|
||||||
|
try:
|
||||||
|
main()
|
||||||
|
except SystemExit:
|
||||||
|
raise
|
||||||
|
except Exception as e:
|
||||||
|
import traceback
|
||||||
|
traceback.print_exc()
|
||||||
|
print(f"[loop_fix] ERROR: {e}")
|
||||||
|
sys.exit(2)
|
||||||
Reference in New Issue
Block a user