Fix T45157: FBX Import could do with better bone alignment in pure-joints armature case.

Note that, since I do not have any skinned zero-aligned bones FBX file at hands, I do not
know whether this option breaks skinning or not (hard to predict, we are playing with
at least four different matrices/transforms here)... Time will say.

3 files changed, 19 insertions, 12 deletions

diff --git a/io_scene_fbx/__init__.py b/io_scene_fbx/__init__.py
index ece5f976..92b32af3 100644
--- a/io_scene_fbx/__init__.py
+++ b/io_scene_fbx/__init__.py
@@ -21,7 +21,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier",
-    "version": (3, 3, 3),
+    "version": (3, 3, 4),
     "blender": (2, 74, 0),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UV's, vertex colors, materials, textures, cameras, lamps and actions",
@@ -100,40 +100,40 @@ class ImportFBX(bpy.types.Operator, ImportHelper, IOFBXOrientationHelper):
             name="Alpha Decals",
             description="Treat materials with alpha as decals (no shadow casting)",
             default=False,
-            options={'HIDDEN'}
             )
     decal_offset = FloatProperty(
             name="Decal Offset",
             description="Displace geometry of alpha meshes",
             min=0.0, max=1.0,
             default=0.0,
-            options={'HIDDEN'}
             )
 
     use_custom_props = BoolProperty(
             name="Import User Properties",
             description="Import user properties as custom properties",
             default=True,
-            options={'HIDDEN'},
             )
     use_custom_props_enum_as_string = BoolProperty(
             name="Import Enums As Strings",
             description="Store enumeration values as strings",
             default=True,
-            options={'HIDDEN'},
             )
 
     ignore_leaf_bones = BoolProperty(
             name="Ignore Leaf Bones",
             description="Ignore the last bone at the end of each chain (used to mark the length of the previous bone)",
             default=False,
-            options={'HIDDEN'},
+            )
+    force_connect_children = BoolProperty(
+            name="Force Connect Children",
+            description="Force connection of children bones to their parent, even if their computed head/tail "
+                        "positions do not match (can be useful with pure-joints-type armatures)",
+            default=False,
             )
     automatic_bone_orientation = BoolProperty(
             name="Automatic Bone Orientation",
             description="Try to align the major bone axis with the bone children",
             default=False,
-            options={'HIDDEN'},
             )
     primary_bone_axis = EnumProperty(
             name="Primary Bone Axis",
@@ -186,6 +186,7 @@ class ImportFBX(bpy.types.Operator, ImportHelper, IOFBXOrientationHelper):
 
         layout.prop(self, "ignore_leaf_bones")
 
+        layout.prop(self, "force_connect_children"),
         layout.prop(self, "automatic_bone_orientation"),
         sub = layout.column()
         sub.enabled = not self.automatic_bone_orientation
diff --git a/io_scene_fbx/fbx_utils.py b/io_scene_fbx/fbx_utils.py
index f5a8e1dd..1058150e 100644
--- a/io_scene_fbx/fbx_utils.py
+++ b/io_scene_fbx/fbx_utils.py
@@ -1227,5 +1227,6 @@ FBXImportSettings = namedtuple("FBXImportSettings", (
     "use_alpha_decals", "decal_offset",
     "use_custom_props", "use_custom_props_enum_as_string",
     "cycles_material_wrap_map", "image_cache",
-    "ignore_leaf_bones", "automatic_bone_orientation", "bone_correction_matrix", "use_prepost_rot",
+    "ignore_leaf_bones", "force_connect_children", "automatic_bone_orientation", "bone_correction_matrix",
+    "use_prepost_rot",
 ))
diff --git a/io_scene_fbx/import_fbx.py b/io_scene_fbx/import_fbx.py
index 7a2808db..2eaf2f95 100644
--- a/io_scene_fbx/import_fbx.py
+++ b/io_scene_fbx/import_fbx.py
@@ -1762,7 +1762,7 @@ class FbxImportHelperNode:
             for child in self.children:
                 child.collect_armature_meshes()
 
-    def build_skeleton(self, arm, parent_matrix, parent_bone_size=1):
+    def build_skeleton(self, arm, parent_matrix, parent_bone_size=1, force_connect_children=False):
         # ----
         # Now, create the (edit)bone.
         bone = arm.bl_data.edit_bones.new(name=self.fbx_name)
@@ -1802,11 +1802,15 @@ class FbxImportHelperNode:
             if child.ignore:
                 continue
             if child.is_bone:
-                child_bone = child.build_skeleton(arm, bone_matrix, bone_size)
+                child_bone = child.build_skeleton(arm, bone_matrix, bone_size,
+                                                  force_connect_children=force_connect_children)
                 # Connection to parent.
                 child_bone.parent = bone
                 if similar_values_iter(bone.tail, child_bone.head):
                     child_bone.use_connect = True
+                elif force_connect_children:
+                    bone.tail = child_bone.head
+                    child_bone.use_connect = True
 
         return bone
 
@@ -1977,7 +1981,7 @@ class FbxImportHelperNode:
                 if child.ignore:
                     continue
                 if child.is_bone:
-                    child_obj = child.build_skeleton(self, Matrix())
+                    child.build_skeleton(self, Matrix(), force_connect_children=settings.force_connect_children)
 
             bpy.ops.object.mode_set(mode='OBJECT')
 
@@ -2075,6 +2079,7 @@ def load(operator, context, filepath="",
          use_custom_props=True,
          use_custom_props_enum_as_string=True,
          ignore_leaf_bones=False,
+         force_connect_children=False,
          automatic_bone_orientation=False,
          primary_bone_axis='Y',
          secondary_bone_axis='X',
@@ -2199,7 +2204,7 @@ def load(operator, context, filepath="",
         use_alpha_decals, decal_offset,
         use_custom_props, use_custom_props_enum_as_string,
         cycles_material_wrap_map, image_cache,
-        ignore_leaf_bones, automatic_bone_orientation, bone_correction_matrix,
+        ignore_leaf_bones, force_connect_children, automatic_bone_orientation, bone_correction_matrix,
         use_prepost_rot,
     )