Nicholas ButzkeandClaude Opus 5
0dd9d01ac7
The skirt glitched when the character moved and the thigh still came through it. Both came from the same place: the solver integrated one spring per bone and then ran four more passes behind it — resolve the collision against the target, resolve it again against the answer, relax the cross-panel links and rebuild every pose from the corrected tips, then walk a separate ancestor "lift" — each writing bone poses the next read back and partly undid. The lift wrote poses that were never fed back into the spring state at all, so every frame began by pulling against a pose the springs did not know about. Replaced with one position-based solve, the shape Magica Cloth 2's BoneCloth uses. Every JOINT is a particle, so a bone's head can move; predict with inertia in the anchor's frame; relax length, bend, backstop, the cross-panel links and the colliders together; convert to rotations once at the end. A contact with no rotational leverage is now resolved by the panel moving, which is what a bodily chain push, an ancestor lift and a drape weight were each approximating separately. Measured, at a dead-still idle and over a movement sweep: idle jitter (skirt) 0.53 -> 0.025 deg/frame, worst 24 -> 1.9 settling after a dash 103 -> 18 mm of leg left inside the skirt fall / air / walk 82 -> 40, 96 -> 75, 72 -> 76 mm run / slide / dash unchanged, ~95 mm The idle buzz and the failure to come home after a hard move are gone — those were the "glitches out". Peak clipping in a run, a slide and a dash is NOT fixed and is still around 95 mm. Four things this turned up on the way: - debug/cloth_clip_check.gd was measuring the animation, not the render. Godot restores bone poses after the modifier pass, so reading them with force_update_all_bone_transforms() afterwards sees nothing any modifier did. It reported the same ~95 mm with collision fully enabled and with it commented out. It now observes from inside the pass. Every number ever taken from this tool before now was measuring the wrong pose. - The collision hulls came from ten farthest-point samples per bone, which describe a panel's corners and hem and leave its MIDDLE unsampled — exactly where a thigh comes through. Built from the real mesh at load time instead. - The drape term is gone. It was there to move a panel the old solver could not, and once the solver could, it was worse in every state but a walk and cost 20x in stability: its target sat inside the leg the collision was pushing out of, so the two ran against each other forever. - Cost was 10.9 ms per character. The inner loop rebuilt every capsule and reallocated the hull array for every (bone, collider, pass). Now 2.6 ms at full quality with a distance LOD behind it. Co-Authored-By: Claude Opus 5 <[email protected]>
82 lines
2.7 KiB
GDScript
82 lines
2.7 KiB
GDScript
extends SceneTree
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## Dev tool: how abruptly does the model change posture when you start running?
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##
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## godot --headless --path . -s res://debug/transition_check.gd -- [skin_glb]
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##
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## Accelerates from a standstill the way the movement code does, then stops, and
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## logs the clip in play plus the body's forward lean each frame. Reports the
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## worst single-frame change in lean and how long the lean took to arrive.
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##
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## Written for "idle to running snaps the character leaning forward". The lean
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## is procedural (ShooterPoseModifier), so it does NOT come from the clip
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## crossfade and is not visible in an animation-blend graph — it was driven by a
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## normalised input direction that steps 0 -> 1 the instant a key goes down,
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## planting a full run posture in ~0.1 s while the Idle->Run crossfade still had
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## 0.4 s to run.
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const ACCEL := 18.0 # m/s^2, roughly the controller's ground acceleration
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const TOP := 9.0 # m/s
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const DT := 1.0 / 60.0
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var _t := 0.0
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var _frames := 0
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var _model: SkinnedPlayerModel = null
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var _speed := 0.0
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var _prev_lean := 0.0
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var _worst_step := 0.0
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var _clip_changes: Array = []
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var _last_clip := ""
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var _t_10 := -1.0
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var _t_90 := -1.0
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var _peak := 0.0
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func _initialize() -> void:
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var args := OS.get_cmdline_user_args()
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var path: String = args[0] if args.size() > 0 \
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else "res://assets/characters/skins/taila.glb"
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var scene := Node3D.new()
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root.add_child(scene)
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current_scene = scene
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_model = SkinnedPlayerModel.new()
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_model.model_path = path
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scene.add_child(_model)
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func _process(_delta: float) -> bool:
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_frames += 1
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if _frames < 8:
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return false
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if not _model.loaded:
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return false
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# Accelerate for 1.5 s, then coast at top speed to 2.5 s.
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_t += DT
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_speed = minf(TOP, _speed + ACCEL * DT) if _t < 2.5 else 0.0
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_model.update_state("ground", _speed, false)
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_model.set_locomotion(0.0, 1.0 if _speed > 0.01 else 0.0, 0.0)
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var lean: float = _model.get_lean_debug()
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if _last_clip != _model.current_clip_debug():
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_last_clip = _model.current_clip_debug()
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_clip_changes.append("%.2fs %s @ %.1f m/s" % [_t, _last_clip, _speed])
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if _t < 2.5:
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_peak = maxf(_peak, lean)
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if _t_10 < 0.0 and lean > 0.1:
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_t_10 = _t
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if _t_90 < 0.0 and lean > 0.9:
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_t_90 = _t
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_worst_step = maxf(_worst_step, absf(lean - _prev_lean))
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_prev_lean = lean
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if _t > 3.5:
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print("\n=== idle -> run transition ===")
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print(" clip changes: " + ", ".join(_clip_changes))
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print(" lean reached 10%% at %.2fs, 90%% at %.2fs (peak %.2f)" % [_t_10, _t_90, _peak])
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print(" worst single-frame lean change: %.4f (%.2f per second at 60fps)"
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% [_worst_step, _worst_step * 60.0])
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print(" a snap looks like ~0.10s to 90%%; a blended move is ~0.6s or more\n")
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return true
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return false
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