FBX Export: WIP attempt to have 'skip_export' objects.

This would allo us e.g. to not export armature object as a root for bone chains,
or to have a real 'only deform' export option, in each case by ignoring some
nodes and 'reparenting' their children to first exported parent.

Idea is simple, but as always when touching to FBX transform (and even worse,
FBX bones binding), it turns into nightmare (a bit like the 'apply transform' issue).

So stuffing this here for now, in case someone (or myself) feels like
wasting another day or two on this mess - with no guarantee of success...

1 files changed, 40 insertions, 24 deletions

diff --git a/io_scene_fbx/export_fbx_bin.py b/io_scene_fbx/export_fbx_bin.py
index cfb57689..35416831 100644
--- a/io_scene_fbx/export_fbx_bin.py
+++ b/io_scene_fbx/export_fbx_bin.py
@@ -714,7 +714,8 @@ def fbx_data_bindpose_element(root, me_obj, me, scene_data, arm_obj=None, mat_wo
 
     elem_data_single_string(fbx_pose, b"Type", b"BindPose")
     elem_data_single_int32(fbx_pose, b"Version", FBX_POSE_BIND_VERSION)
-    elem_data_single_int32(fbx_pose, b"NbPoseNodes", 1 + (1 if (arm_obj != me_obj) else 0) + len(bones))
+    elem_data_single_int32(fbx_pose, b"NbPoseNodes",
+                           1 + (1 if (arm_obj != me_obj and mat_world_arm) else 0) + len(bones))
 
     # First node is mesh/object.
     mat_world_obj = me_obj.fbx_object_matrix(scene_data, global_space=True)
@@ -722,7 +723,7 @@ def fbx_data_bindpose_element(root, me_obj, me, scene_data, arm_obj=None, mat_wo
     elem_data_single_int64(fbx_posenode, b"Node", me_obj.fbx_uuid)
     elem_data_single_float64_array(fbx_posenode, b"Matrix", matrix4_to_array(mat_world_obj))
     # Second node is armature object itself.
-    if arm_obj != me_obj:
+    if arm_obj != me_obj and mat_world_arm:
         fbx_posenode = elem_empty(fbx_pose, b"PoseNode")
         elem_data_single_int64(fbx_posenode, b"Node", arm_obj.fbx_uuid)
         elem_data_single_float64_array(fbx_posenode, b"Matrix", matrix4_to_array(mat_world_arm))
@@ -1400,10 +1401,10 @@ def fbx_data_armature_elements(root, arm_obj, scene_data):
         * Deformers (i.e. Skin), bind between an armature and a mesh.
         ** SubDeformers (i.e. Cluster), one per bone/vgroup pair.
         * BindPose.
-    Note armature itself has no data, it is a mere "Null" Model...
+    Note armature itself has no data, it is a mere "Null" Model (when exported)...
     """
-    mat_world_arm = arm_obj.fbx_object_matrix(scene_data, global_space=True)
-    bones = tuple(bo_obj for bo_obj in arm_obj.bones if bo_obj in scene_data.objects)
+    mat_world_arm = arm_obj.fbx_object_matrix(scene_data, global_space=True) if not arm_obj.skip_export else None
+    bones = tuple(bo_obj for bo_obj in arm_obj.bones if bo_obj in scene_data.objects and not bo_obj.skip_export)
 
     bone_radius_scale = 33.0
 
@@ -1489,7 +1490,8 @@ def fbx_data_armature_elements(root, arm_obj, scene_data):
                 elem_data_single_float64_array(fbx_clstr, b"Transform",
                                                matrix4_to_array(mat_world_bones[bo_obj].inverted_safe() * mat_world_obj))
                 elem_data_single_float64_array(fbx_clstr, b"TransformLink", matrix4_to_array(mat_world_bones[bo_obj]))
-                elem_data_single_float64_array(fbx_clstr, b"TransformAssociateModel", matrix4_to_array(mat_world_arm))
+                if mat_world_arm:
+                    elem_data_single_float64_array(fbx_clstr, b"TransformAssociateModel", matrix4_to_array(mat_world_arm))
 
 
 def fbx_data_leaf_bone_elements(root, scene_data):
@@ -1753,8 +1755,11 @@ def fbx_skeleton_from_armature(scene, settings, arm_obj, objects, data_meshes,
     Also supports "parent to bone" (simple parent to Model/LimbNode).
     arm_parents is a set of tuples (armature, object) for all successful armature bindings.
     """
-    # We need some data for our armature 'object' too!!!
-    data_empties[arm_obj] = get_blender_empty_key(arm_obj.bdata)
+    if (settings.use_armature_as_root):
+        # We need some data for our armature 'object' too!!!
+        data_empties[arm_obj] = get_blender_empty_key(arm_obj.bdata)
+    else:
+        arm_obj.skip_export = True
 
     arm_data = arm_obj.bdata.data
     bones = OrderedDict()
@@ -1812,11 +1817,14 @@ def fbx_skeleton_from_armature(scene, settings, arm_obj, objects, data_meshes,
 
 
 def fbx_generate_leaf_bones(settings, data_bones):
-    # find which bons have no children
+    # find which bones have no children.
     child_count = {bo: 0 for bo, _bo_key in data_bones.items()}
     for bo, _bo_key in data_bones.items():
-        if bo.parent and bo.parent.is_bone:
-            child_count[bo.parent] += 1
+        if bo.skip_export:
+            continue
+        bo_par = bo.fbx_parent
+        if bo_par and bo_par.is_bone:
+            child_count[bo_par] += 1
 
     bone_radius_scale = settings.global_scale * 33.0
 
@@ -2317,7 +2325,8 @@ def fbx_data_from_scene(scene, settings):
         templates[b"Camera"] = fbx_template_def_camera(scene, settings, nbr_users=len(data_cameras))
 
     if data_bones:
-        templates[b"Bone"] = fbx_template_def_bone(scene, settings, nbr_users=len(data_bones))
+        nbr_users = sum(1 for db in data_bones if not db.skip_export)
+        templates[b"Bone"] = fbx_template_def_bone(scene, settings, nbr_users=nbr_users)
 
     if data_meshes:
         nbr = len(data_meshes)
@@ -2326,7 +2335,8 @@ def fbx_data_from_scene(scene, settings):
         templates[b"Geometry"] = fbx_template_def_geometry(scene, settings, nbr_users=nbr)
 
     if objects:
-        templates[b"Model"] = fbx_template_def_model(scene, settings, nbr_users=len(objects))
+        nbr_users = sum(1 for ob in objects if not ob.skip_export)
+        templates[b"Model"] = fbx_template_def_model(scene, settings, nbr_users=nbr_users)
 
     if arm_parents:
         # Number of Pose|BindPose elements should be the same as number of meshes-parented-to-armatures
@@ -2389,22 +2399,25 @@ def fbx_data_from_scene(scene, settings):
     for ob_obj in objects:
         # Bones are handled later.
         if not ob_obj.is_bone:
-            par_obj = ob_obj.parent
+            par_obj = ob_obj.fbx_parent
             # Meshes parented to armature are handled separately, yet we want the 'no parent' connection (0).
-            if par_obj and ob_obj.has_valid_parent(objects) and (par_obj, ob_obj) not in arm_parents:
+            if par_obj and ob_obj.has_valid_fbx_parent(objects) and (par_obj, ob_obj) not in arm_parents:
                 connections.append((b"OO", ob_obj.fbx_uuid, par_obj.fbx_uuid, None))
             else:
                 connections.append((b"OO", ob_obj.fbx_uuid, 0, None))
 
     # Armature & Bone chains.
     for bo_obj in data_bones.keys():
-        par_obj = bo_obj.parent
-        if par_obj not in objects:
-            continue
-        connections.append((b"OO", bo_obj.fbx_uuid, par_obj.fbx_uuid, None))
+        par_obj = bo_obj.fbx_parent
+        if par_obj is None:
+            connections.append((b"OO", bo_obj.fbx_uuid, 0, None))
+        elif par_obj in objects:
+            connections.append((b"OO", bo_obj.fbx_uuid, par_obj.fbx_uuid, None))
 
     # Object data.
     for ob_obj in objects:
+        if ob_obj.skip_export:
+            continue
         if ob_obj.is_bone:
             bo_data_key = data_bones[ob_obj]
             connections.append((b"OO", get_fbx_uuid_from_key(bo_data_key), ob_obj.fbx_uuid, None))
@@ -2729,7 +2742,7 @@ def fbx_objects_elements(root, scene_data):
     perfmon.step("FBX export fetch objects (%d)..." % len(scene_data.objects))
 
     for ob_obj in scene_data.objects:
-        if ob_obj.is_dupli:
+        if ob_obj.is_dupli or ob_obj.skip_export:
             continue
         fbx_data_object_elements(objects, ob_obj, scene_data)
         ob_obj.dupli_list_create(scene_data.scene, 'RENDER')
@@ -2802,6 +2815,7 @@ def fbx_takes_elements(root, scene_data):
 # ##### "Main" functions. #####
 
 # This func can be called with just the filepath
+# Warning! Arg order is not guaranteed, only use keyargs!
 def save_single(operator, scene, filepath="",
                 global_matrix=Matrix(),
                 apply_unit_scale=False,
@@ -2811,7 +2825,11 @@ def save_single(operator, scene, filepath="",
                 object_types=None,
                 use_mesh_modifiers=True,
                 mesh_smooth_type='FACE',
+                use_armature_as_root=True,
                 use_armature_deform_only=False,
+                add_leaf_bones=False,
+                primary_bone_axis='Y',
+                secondary_bone_axis='X',
                 bake_anim=True,
                 bake_anim_use_all_bones=True,
                 bake_anim_use_nla_strips=True,
@@ -2819,9 +2837,6 @@ def save_single(operator, scene, filepath="",
                 bake_anim_step=1.0,
                 bake_anim_simplify_factor=1.0,
                 bake_anim_force_startend_keying=True,
-                add_leaf_bones=False,
-                primary_bone_axis='Y',
-                secondary_bone_axis='X',
                 use_metadata=True,
                 path_mode='AUTO',
                 use_mesh_edges=True,
@@ -2881,7 +2896,8 @@ def save_single(operator, scene, filepath="",
         bake_space_transform, global_matrix_inv, global_matrix_inv_transposed,
         context_objects, object_types, use_mesh_modifiers,
         mesh_smooth_type, use_mesh_edges, use_tspace,
-        use_armature_deform_only, add_leaf_bones, bone_correction_matrix, bone_correction_matrix_inv,
+        use_armature_as_root, use_armature_deform_only, add_leaf_bones,
+        bone_correction_matrix, bone_correction_matrix_inv,
         bake_anim, bake_anim_use_all_bones, bake_anim_use_nla_strips, bake_anim_use_all_actions,
         bake_anim_step, bake_anim_simplify_factor, bake_anim_force_startend_keying,
         False, media_settings, use_custom_props,