Load FBX characters directly: in-app conversion to GLB

The model button now accepts .fbx too: a new model:convert IPC runs
Blender with scripts/fbx2modelglb.py (mesh + skin kept, animations
dropped, embedded diffuse recovered even when the FBX references
missing external textures) into userData/models3d, then the resulting
GLB loads as usual. anim/model conversion share one convertFbx helper.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/fbx2modelglb.py

@@ -0,0 +1,60 @@
+# Convert a character FBX (e.g. a Mixamo T-pose download) into a GLB model
+# for DJ Visualizer: mesh + skeleton/skin kept, animations dropped (the dance
+# library provides the moves), embedded diffuse texture recovered even when
+# the FBX references missing external files.
+#   blender -b -P fbx2modelglb.py -- input.fbx output.glb
+import bpy, sys, os
+argv = sys.argv[sys.argv.index('--')+1:]
+SRC, OUT = argv[0], argv[1]
+TMP = OUT + '.diffuse.png'
+bpy.ops.wm.read_factory_settings(use_empty=True)
+bpy.ops.import_scene.fbx(filepath=SRC)
+arm = None; meshes = []
+for o in bpy.data.objects:
+    if o.type == 'ARMATURE' and arm is None:
+        arm = o
+    if o.type == 'MESH':
+        meshes.append(o)
+if not meshes:
+    raise SystemExit('nessuna mesh nel file')
+# drop any animation, keep the rest pose
+for o in bpy.data.objects:
+    o.animation_data_clear()
+for a in list(bpy.data.actions):
+    bpy.data.actions.remove(a)
+if arm:
+    for pb in arm.pose.bones:
+        pb.location = (0, 0, 0)
+        pb.rotation_quaternion = (1, 0, 0, 0)
+        pb.scale = (1, 1, 1)
+# recover the diffuse: prefer an embedded image that actually has data
+valid = [i for i in bpy.data.images if i.has_data and i.size[0] > 0]
+diff = next((i for i in valid if 'Diffuse' in i.name), valid[0] if valid else None)
+if diff:
+    try:
+        diff.filepath_raw = TMP
+        diff.file_format = 'PNG'
+        diff.save()
+        diff = bpy.data.images.load(TMP)
+        diff.pack()
+        mat = bpy.data.materials.new('skin')
+        mat.use_nodes = True
+        bsdf = next(n for n in mat.node_tree.nodes if n.type == 'BSDF_PRINCIPLED')
+        tex = mat.node_tree.nodes.new('ShaderNodeTexImage')
+        tex.image = diff
+        mat.node_tree.links.new(bsdf.inputs['Base Color'], tex.outputs['Color'])
+        for m in meshes:
+            m.data.materials.clear()
+            m.data.materials.append(mat)
+    except Exception as e:
+        print('texture non recuperata:', e)
+try:
+    bpy.ops.export_scene.gltf(filepath=OUT, export_format='GLB', export_animations=False,
+        export_skins=True, export_rest_position_armature=True)
+except TypeError:
+    bpy.ops.export_scene.gltf(filepath=OUT, export_format='GLB', export_animations=False, export_skins=True)
+try:
+    os.remove(TMP)
+except OSError:
+    pass
+print('EXPORT_OK')