Fix the wrist/hand detachment: wrist tracks the hand bone, sleeve cuff follows the hand, hand raised to meet the wrist

tools/blender_assets.py

@@ -566,7 +566,7 @@ def _skin_body(spec):
             ((0.20 * s * w, 0, 1.37), 0.080 * t * sleeve, 0.074 * t * sleeve),  # shoulder
             ((0.27 * s * w, 0, 1.23), 0.058 * t * sleeve, 0.058 * t * sleeve),  # upper arm
             ((0.275 * s * w, 0.005, 1.06), 0.046 * t * sleeve, 0.048 * t * sleeve),  # elbow
-            ((0.275 * s * w, -0.01, 0.80), 0.034 * t, 0.030 * t),  # wrist
+            ((0.275 * s * w, -0.01, 0.78), 0.034 * t, 0.030 * t),  # wrist
         ]
         edges += [(3, base), (base, base + 1), (base + 1, base + 2), (base + 2, base + 3)]
         hb = len(nodes)
@@ -666,9 +666,15 @@ def _auto_weights(obj, layout, rigid=None):
                 groups[bone].add([v.index], 1.0, "REPLACE")
                 continue
         if abs(p.x) > 0.19 and p.z > 0.74 and p.z < 1.42:
-            allowed = ["Spine", f"Shoulder{side}", f"Elbow{side}", f"Hand{side}"]
-            if abs(p.x) > 0.23:
-                allowed.remove("Spine")
+            if p.z < 0.82:
+                # Wrist: track the Hand bone fully so the forearm-end moves with
+                # the rigid hand (the old Hand+Elbow blend left a visible gap at
+                # the wrist when the hand rotated).
+                allowed = [f"Hand{side}"]
+            else:
+                allowed = ["Spine", f"Shoulder{side}", f"Elbow{side}", f"Hand{side}"]
+                if abs(p.x) > 0.23:
+                    allowed.remove("Spine")
         elif p.z < 0.80:
             allowed = ["Hips", f"Hip{side}", f"Knee{side}"]
             if p.z < 0.66:
@@ -848,26 +854,26 @@ def _hands_and_shoes(mats, spec):
     for s in (-1.0, 1.0):
         x = 0.275 * s * w
         # Wider and shallower than the old ball: a palm, not a wrist knob.
-        parts.append(sphere("Palm", 0.046, (x, -0.012, 0.742), skin, seg=10, rings=6,
+        parts.append(sphere("Palm", 0.046, (x, -0.012, 0.762), skin, seg=10, rings=6,
                             scale=(0.80, 0.62, 0.88)))
         # Four bent, tapering fingers with rounded tips. The two segments keep
         # the hand readable at conversation distance without adding a full
         # finger skeleton; the outer fingers are slightly shorter.
         for index, offset in enumerate((-0.024, -0.008, 0.008, 0.024)):
             fx = x + offset * s
-            tip_z = (0.692, 0.681, 0.684, 0.694)[index]
+            tip_z = (0.712, 0.701, 0.704, 0.714)[index]
             radius = 0.0115 if index in (1, 2) else 0.0105
-            parts.append(tube("Finger", [(fx, -0.018, 0.758),
-                                         (fx, -0.030, 0.726),
+            parts.append(tube("Finger", [(fx, -0.018, 0.778),
+                                         (fx, -0.030, 0.746),
                                          (fx, -0.042, tip_z)],
                               radius, skin, seg=6, caps=False))
             parts.append(sphere("Fingertip", radius, (fx, -0.042, tip_z), skin,
                                 seg=6, rings=4))
-        parts.append(tube("Thumb", [(x - 0.010 * s, -0.018, 0.758),
-                                    (x - 0.028 * s, -0.040, 0.740),
-                                    (x - 0.034 * s, -0.055, 0.718)],
+        parts.append(tube("Thumb", [(x - 0.010 * s, -0.018, 0.778),
+                                    (x - 0.028 * s, -0.040, 0.760),
+                                    (x - 0.034 * s, -0.055, 0.738)],
                           0.012, skin, seg=6, caps=False))
-        parts.append(sphere("ThumbTip", 0.012, (x - 0.034 * s, -0.055, 0.718), skin,
+        parts.append(sphere("ThumbTip", 0.012, (x - 0.034 * s, -0.055, 0.738), skin,
                             seg=6, rings=4))
         parts.append(box("Shoe", (0.10, 0.25, 0.075), (0.12 * s, -0.045, 0.04), shoe,
                          bevel=0.028, segs=1))
@@ -1012,7 +1018,9 @@ def build_character(name):
                 return "Head" if p.z > 1.55 else "Neck"
             side = "L" if p.x < 0 else "R"
             if abs(p.x) > 0.26 and p.z > 0.8:
-                return f"Elbow{side}"
+                # Sleeve: the cuff follows the hand, the upper sleeve the elbow,
+                # so the sleeve does not separate from the hand at the wrist.
+                return f"Hand{side}" if p.z < 1.06 else f"Elbow{side}"
             if p.z < 0.25:
                 return f"Knee{side}"
             return None