Nicholas ButzkeandClaude Opus 5
b1c8bab714
The lab could move the GUN and not the anchor points the hands are solved onto. `grip_offset` slides the weapon around inside the fist; `gun_fore` and `gun_stock` are distances ALONG the barrel, so the trigger and support hands could travel up and down the weapon's own axis and nowhere else. Nothing could take a hand off that axis, which is what a handguard below the bore, an angled foregrip, or a pistol whose grip is nowhere near its barrel line all need. Two things fix that. `grip_shift` and `fore_shift` give the two hand anchors real three-dimensional freedom, expressed in the GUN's own across/up/along frame so a sideways nudge stays sideways as the weapon pitches between low ready and ADS. Zero is exactly the old behaviour. Their z overlaps the along-axis distances, which is redundant and deliberate: keeping those separate is what lets the reach solver slide the support hand back down the handguard without undoing a considered sideways offset. And the markers are now draggable. They already showed the anchors; now they are handles. The one under the mouse swells and draws through the body — depth testing is right for judging whether a hand reached its target and wrong for a handle, because at any useful framing the hands occlude all three. Verified three ways, and each one had to be rebuilt once: anchor_shift_check first compared absolute positions and reported a 3.5 mm error that was the character BREATHING — there is a sin() on the muzzle pitch, so no anchor is ever in the same place twice. Measuring each anchor relative to the one it hangs off, rotated into the current gun basis, cancels the breathing, the ADS blend and the recoil exactly. 48 checks, six characters, both poses. anchor_drag_check asserts the drag writes the knob the MOUSE asked for, derived independently from the camera: 0.00-0.01 mm on all three. It does not assert the marker lands under the cursor, because it does not — the anchors hang off the shoulder and the arm chasing them moves the shoulder, so a drag settles at 0.77x-1.13x. Small enough to ignore interactively. That feedback first read as 1.5x-1.8x, because the cases were compounding on each other, and waiting LONGER for the pose to settle made it worse rather than better — which is the opposite of how a settling error behaves and is what gave it away. The buttstock case also failed for a while on a bug entirely in the test: it read an absent knob as zero when `pocket_hip` defaults to (30, -70, 60) mm. The lab has a note about that trap in `_reset`. It is just as easy to walk into from a test, and now has one there too. Co-Authored-By: Claude Opus 5 <[email protected]>
162 lines
8.5 KiB
Markdown
162 lines
8.5 KiB
Markdown
# Verification — and the trap that invalidated all of it
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## READ THIS FIRST
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**Godot restores every bone's local pose after the `SkeletonModifier3D` pass.**
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So calling `force_update_all_bone_transforms()` and reading
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`get_bone_global_pose()` from a `SceneTree` script, from `_process`, or anywhere
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outside that pass recomputes the globals from the **animation alone**. The
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shooter pose layer and the cloth solver are simply not in what you measure.
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`debug/cloth_clip_check.gd` did exactly this. It reported the same ~95 mm of
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leg-inside-skirt with collision fully enabled **and with the collision call
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commented out**. Every number ever taken from that tool before 2026-07-26 is
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void, and several rounds of "tuning did nothing" in the history were reading a
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pose the solver never touched.
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**To measure a pose layer, add your own `SkeletonModifier3D` as a child of the
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`Skeleton3D` AFTER the one you care about, and snapshot inside its
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`_process_modification()`.** The `PoseProbe` class in `cloth_clip_check.gd` and
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`travel_dir_check.gd` is the pattern.
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Two related traps:
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- **Headless runs uncapped**, so the engine delta is sub-millisecond and anything
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integrated barely moves. Set `SpringBones.fixed_delta = 1.0/60.0`.
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- **A single frame of a locomotion clip measures the clip.** A run cycle twists
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the torso against the hips by tens of degrees twice per stride, swamping
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anything a pose layer does. Average over a stride.
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## The tools
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| Tool | Measures | Good |
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|---|---|---|
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| `spawn_smoke_test.gd` | spawn, skins, anim tree, camera, state cycling | 29 OK, 0 failures |
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| `cloth_clip_check.gd` | leg-inside-cloth per movement state, per vertex | idle < 25 mm |
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| `cloth_settle_check.gd` | deg/frame at a dead idle, contacts/frame | skirt < 0.1, hair < 0.01 |
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| `cloth_perf_check.gd` | ms per character per frame | ~2.6 ms |
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| `cloth_allow_check.gd` | how much of each limb the rest-clearance cap makes the solver blind to | 17–35 mm on Taila |
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| `cloth_stretch_check.gd` | mesh tearing between panels | no 3× edges |
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| `travel_dir_check.gd` | stride direction vs. travel direction | < 10° except a capped sidestep |
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| `limb_deform_check.gd` | joint collapse | knee ~0.99 |
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| `verify_character.py` | meshes, bones, weights of a SOURCE model | several meshes, cloth bones present |
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| `surface_class_check.gd` | every surface resolves from the sidecar, not the fallback | 0 fallbacks on all six skins |
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| `character_picker_check.gd` | the escape-menu roster: skeleton, clips, surfaces, and that the pose MOVES | 0 failures |
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| `rig_anchor_check.gd` | a grip anchor physically moves the weapon, and clears | 0 failures |
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| `anchor_shift_check.gd` | the hand anchors move in the GUN's frame, both poses | 0 failures |
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| `anchor_drag_check.gd` | dragging a marker writes the knob the mouse asked for | 0 failures |
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| `anim_capture.gd` / `orbit_capture.gd` | renders, for looking | — |
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| `roster_capture.gd` | one photo of every character, from the picker | — |
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| `ui_capture.gd` | one photo of every menu screen | — |
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| `rest_pose_check.gd` | each rig's bind-pose limb directions vs. the library's | see below |
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## What `rest_pose_check` actually established
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It was written to test a suspicion — that the rest-relative retarget silently
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assumes both rigs rest alike — and it disproved it. Miku's arms rest **41°** off
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the animation library's and Taila's **32°**, and both animate correctly. The
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delta retarget handles a rest-pose difference, which is what it is for. Do not
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go looking there again.
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It also demonstrates the measurement trap in miniature. Written as "the direction
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from a bone to its FIRST CHILD", it reported kiyoko's and aria's legs 71° off —
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because a thigh's first child is as likely to be a skirt bone as a shin, and it
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was measuring the hang of a skirt panel. Pointing it at the next limb BY ROLE
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dropped both to 1°. The same rule as everywhere else in this pipeline: resolve
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roles, never take whatever the rig happens to hand you.
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## Assert the consequence, not the plumbing
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Three of these exist because the obvious check passes on a broken system.
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- `character_picker_check` asserts the skeleton's pose CHANGES over a dozen
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frames. Asking the model which clip it is playing does not work: that is a
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variable the class sets on itself, and it reads `"Idle"` just as happily when
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the animation tree is not ticking at all.
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- `rig_anchor_check` asserts the weapon MOVES by the offset asked for. An anchor
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system is easy to build so that the sliders move, the file saves and the JSON
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round-trips while the gun does not budge — the value read into a variable
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nobody consumed. It measures in the attachment's frame, not the world's:
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the attachment tracks a bone on an animating skeleton, so a world-space delta
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is mostly the idle animation.
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- `anchor_shift_check` and `anchor_drag_check` both measure in the GUN's frame
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rather than the world's, and have to. The hold BREATHES — a
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`sin(_time * 2.2) * 0.012` on the muzzle pitch — so no anchor is ever at the
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same world position twice, and comparing absolute positions reported a 3.5 mm
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error that was the character inhaling. Taking each anchor relative to the one
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it hangs off and rotating into the current gun basis cancels the breathing,
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the ADS blend and the recoil kick exactly, because all three move the basis
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and the anchor together.
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- `surface_class_check` FAILS on a surface that falls through to the heuristic
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instead of resolving from the table. A model whose names stopped matching still
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renders — the fallback catches it — and quietly loses its per-class art
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direction. Nothing else would report that.
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And four of the last five real defects came from LOOKING, not from asserting:
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a preview showing the back of the character's head, a turntable that carried on
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from the previous character, an unstyled list, and momo's idle pose. Every one
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passed every assertion. Run `roster_capture` and `ui_capture` and open the PNGs.
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Run them:
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```bash
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godot --headless --path . -s res://debug/<tool>.gd
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godot --headless --path . -s res://debug/<tool>.gd -- res://assets/characters/skins/<name>.glb
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```
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Scripts run with `-s` MUST extend `SceneTree`. A `Node` script never quits and
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hangs forever.
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## Measure the right quantity
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`cloth_clip_check.gd` used to report "how much CLOSER the leg got than the artist
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modelled it". A hem 200 mm clear of a shin legitimately comes 180 mm closer when
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the leg kicks out in a slide, and counting that as a failure buried the real
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clipping under motion the character is supposed to have. It now reports how far
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INSIDE a capsule a cloth vertex is, over and above however far inside it was
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modelled — only cloth actually within the capsule can be showing a leg through.
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It also applies the collider's `from` offset, so it tests the same band of thigh
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the solver is defending. Measuring the full bone tests the hip cap the solver
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deliberately excludes and reports it as clipping no tuning can fix.
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## What the suite still does not check
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It verifies that a character is WELL-FORMED, not that it is CORRECT. Those are
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different properties, and only the first was ever asserted — which is how four
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characters shipped "All checks passed" while lying on their backs, seven times
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too large, facing backwards, or unable to hold a gun. See `failure-modes.md`.
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`posture` and `bone roles reachable at runtime` are now hard checks. Still
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missing, and worth adding when a source next exposes them: facing measured on the
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OUTPUT, and per-vertex validation that a generated cloth chain actually tracks
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the geometry it was given.
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## Diagnosing "the solver isn't working"
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In order:
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1. **Is the measurement inside the modifier pass?** (Above. Do this first.)
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2. **Does the solver SEE the contact?** `debug_hit_report()` — bone → deepest
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overlap it found. If ~0 while the mesh is deep inside a leg, the collision
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hull does not cover the geometry that is clipping.
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3. **Does it CONVERGE?** `debug_residual_report()` — overlap left after the
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relaxation. Seen 93 mm, left 95 mm is a standing fight, not slow convergence;
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quadrupling the iterations will buy nothing. Find what is pulling back.
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4. **Only then, tune.**
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That order was learned the hard way: the drape, the bend limits, the backstop,
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the iteration count and the hull sampling were each suspected and tested, and
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the answer was in step 1.
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## Also run
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```bash
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godot --headless --path . -s res://movement/tests/run_fsm_tests.gd # 11 tests
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godot --headless --path . --check-only --script res://<file>.gd # syntax
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```
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Autoload identifiers report false "not found" errors under `--check-only` —
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ignore those.
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