glTF exporter: Reset pose bone between each action

io_scene_gltf2/__init__.py

@@ -4,7 +4,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (3, 4, 21),
+    "version": (3, 4, 22),
     'blender': (3, 3, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
@@ -418,6 +418,15 @@ class ExportGLTF2_Base:
         default=True
     )
 
+    export_reset_pose_bones: BoolProperty(
+        name='Reset pose bones between actions',
+        description=(
+            "Reset pose bones between each action exported. "
+            "This is needed when some bones are not keyed on some animations"
+        ),
+        default=True
+    )
+
     export_current_frame: BoolProperty(
         name='Use Current Frame',
         description='Export the scene in the current animation frame',
@@ -597,12 +606,14 @@ class ExportGLTF2_Base:
             export_settings['gltf_nla_strips_merged_animation_name'] = self.export_nla_strips_merged_animation_name
             export_settings['gltf_optimize_animation'] = self.export_optimize_animation_size
             export_settings['gltf_export_anim_single_armature'] = self.export_anim_single_armature
+            export_settings['gltf_export_reset_pose_bones'] = self.export_reset_pose_bones
         else:
             export_settings['gltf_frame_range'] = False
             export_settings['gltf_move_keyframes'] = False
             export_settings['gltf_force_sampling'] = False
             export_settings['gltf_optimize_animation'] = False
             export_settings['gltf_export_anim_single_armature'] = False
+            export_settings['gltf_export_reset_pose_bones'] = False
         export_settings['gltf_skins'] = self.export_skins
         if self.export_skins:
             export_settings['gltf_all_vertex_influences'] = self.export_all_influences
@@ -957,6 +968,7 @@ class GLTF_PT_export_animation_export(bpy.types.Panel):
             layout.prop(operator, 'export_nla_strips_merged_animation_name')
         layout.prop(operator, 'export_optimize_animation_size')
         layout.prop(operator, 'export_anim_single_armature')
+        layout.prop(operator, 'export_reset_pose_bones')
 
 
 class GLTF_PT_export_animation_shapekeys(bpy.types.Panel):

io_scene_gltf2/blender/exp/gltf2_blender_gather_animations.py

@@ -11,6 +11,7 @@ from ..com.gltf2_blender_extras import generate_extras
 from io_scene_gltf2.io.exp.gltf2_io_user_extensions import export_user_extensions
 from io_scene_gltf2.blender.exp.gltf2_blender_gather_tree import VExportNode
 from ..com.gltf2_blender_data_path import is_bone_anim_channel
+from mathutils import Matrix
 
 
 def gather_animations(  obj_uuid: int,
@@ -91,6 +92,7 @@ def gather_animations(  obj_uuid: int,
                 if blender_object.animation_data.is_property_readonly('action'):
                     blender_object.animation_data.use_tweak_mode = False
                 try:
+                    __reset_bone_matrix(blender_object, export_settings)
                     blender_object.animation_data.action = blender_action
                 except:
                     error = "Action is readonly. Please check NLA editor"
@@ -117,9 +119,11 @@ def gather_animations(  obj_uuid: int,
         if blender_object.animation_data.action is not None:
             if current_action is None:
                 # remove last exported action
+                __reset_bone_matrix(blender_object, export_settings)
                 blender_object.animation_data.action = None
             elif blender_object.animation_data.action.name != current_action.name:
                 # Restore action that was active at start of exporting
+                __reset_bone_matrix(blender_object, export_settings)
                 blender_object.animation_data.action = current_action
         if solo_track is not None:
             solo_track.is_solo = True
@@ -323,4 +327,20 @@ def __is_armature_action(blender_action) -> bool:
     for fcurve in blender_action.fcurves:
         if is_bone_anim_channel(fcurve.data_path):
             return True
-    return False
+    return False
\ No newline at end of file
+
+def __reset_bone_matrix(blender_object, export_settings) -> None:
+    if export_settings['gltf_export_reset_pose_bones'] is False:
+        return
+
+    # Only for armatures
+    if blender_object.type != "ARMATURE":
+        return
+
+    # Remove current action if any
+    if blender_object.animation_data and blender_object.animation_data.action:
+        blender_object.animation_data.action = None
+
+    # Resetting bones TRS to avoid to keep not keyed value on a future action set
+    for bone in blender_object.pose.bones:
+        bone.matrix_basis = Matrix()