characters/skin_leg_repair.gd

@@ -35,6 +35,8 @@ class_name SkinLegRepair
 ##   3. Drop any triangle still spanning the two legs below the knee. Those are
 ##      the midline band between the ankles, which has no correct pose either
 ##      way.
+##
+## Measure with debug/limb_deform_check.gd.
 
 const LEG_BONE_HINTS := ["thigh", "shin", "foot", "toe"]
 ## Ignore influences below this — they are rounding, not real weighting.

debug/limb_deform_check.gd

@@ -16,10 +16,23 @@ extends SceneTree
 ##               collapse that linear-blend skinning causes at a bent joint;
 ##               0.85-1.00 is normal, well below that is a weighting fault.
 ##
-## Written after four rounds of chasing reported leg "squashing". Renders were
-## repeatedly misleading — a slim anime leg at full stride genuinely looks
-## stretched — so measure before changing anything, and prefer this over
-## eyeballing a screenshot.
+## Written after several rounds of chasing reported leg "squashing". Renders
+## were repeatedly misleading — a slim anime leg at full stride genuinely looks
+## stretched — so measure before changing anything.
+##
+## READ THIS BEFORE TRUSTING ANY NUMBER YOU ADD HERE. Two earlier versions of
+## this measurement were themselves wrong and nearly caused a bad "fix":
+##
+##   * Comparing skinned lengths against BIND-POSE lengths. The character is
+##     never in bind pose, so ordinary posing showed up as 0.4x-2.5x
+##     "deformation" even with the animation frozen.
+##   * Flagging vertices weighted across "non-adjacent" leg bones by testing
+##     max_slot - min_slot >= 2. That flags shin+foot+toe, which is a perfectly
+##     normal contiguous run.
+##
+## So the baseline here is the skeleton's REST transforms, which makes every
+## ratio exactly 1.00 when the pose is the rest pose — the tool validates
+## itself. If you add a metric, prove it reads 1.00 on an unposed model first.
 
 var _frames := 0
 var _model: SkinnedPlayerModel = null
@@ -51,7 +64,7 @@ func _process(_delta: float) -> bool:
 	if _frames < 10:
 		return false
 	if _frames == 10:
-		_measure(true)
+		_measure(true)   # baseline from the skeleton's REST transforms
 		return false
 	var phase: int = clampi((_frames - 20) / FRAMES_PER_STATE, 0, SWEEP.size() - 1)
 	_model.update_state(SWEEP[phase][0], SWEEP[phase][1], false)
@@ -107,9 +120,12 @@ func _measure(store_rest: bool) -> void:
 			_rings(skel, skin, bone_of, mname, verts, bones, weights, per, store_rest)
 
 
+## `rest` skins against the skeleton's rest transforms instead of its current
+## pose, which is what makes the baseline exact: ratios come out 1.00 on an
+## unposed model, so a wrong reading is visible immediately.
 func _skinned(skel: Skeleton3D, skin: Skin, bone_of: Dictionary, p: Vector3,
 		bones: PackedInt32Array, weights: PackedFloat32Array,
-		base: int, per: int) -> Vector3:
+		base: int, per: int, rest: bool = false) -> Vector3:
 	var q := Vector3.ZERO
 	for k in per:
 		var w: float = weights[base + k]
@@ -119,7 +135,8 @@ func _skinned(skel: Skeleton3D, skin: Skin, bone_of: Dictionary, p: Vector3,
 		var bi: int = bone_of[bind]
 		if bi < 0:
 			continue
-		q += (skel.get_bone_global_pose(bi) * skin.get_bind_pose(bind) * p) * w
+		var m: Transform3D = skel.get_bone_global_rest(bi) if rest else skel.get_bone_global_pose(bi)
+		q += (m * skin.get_bind_pose(bind) * p) * w
 	return q
 
 
@@ -140,7 +157,7 @@ func _span(skel: Skeleton3D, skin: Skin, bone_of: Dictionary, mname: String,
 		var t: float = clampf((p - ha).dot(hf) / hf.length_squared(), 0.0, 1.0)
 		if p.distance_to(ha + hf * t) > 0.10:
 			continue
-		var q := _skinned(skel, skin, bone_of, p, bones, weights, v * per, per)
+		var q := _skinned(skel, skin, bone_of, p, bones, weights, v * per, per, store_rest)
 		lo = Vector3(minf(lo.x, q.x), minf(lo.y, q.y), minf(lo.z, q.z))
 		hi = Vector3(maxf(hi.x, q.x), maxf(hi.y, q.y), maxf(hi.z, q.z))
 		n += 1
@@ -177,7 +194,7 @@ func _rings(skel: Skeleton3D, skin: Skin, bone_of: Dictionary, mname: String,
 				continue
 			if p.distance_to(a + ab * t) > 0.09:
 				continue
-			var q := _skinned(skel, skin, bone_of, p, bones, weights, v * per, per)
+			var q := _skinned(skel, skin, bone_of, p, bones, weights, v * per, per, store_rest)
 			sp.append(q)
 			c += q
 		if sp.size() < 3: