glTF exporter: add some checks on animation data, fixing error with weird files

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (0, 9, 44),
+    "version": (0, 9, 45),
     'blender': (2, 80, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_channels.py

@@ -148,6 +148,9 @@ def __gather_target(channels: typing.Tuple[bpy.types.FCurve],
 def __get_channel_groups(blender_action: bpy.types.Action, blender_object: bpy.types.Object, export_settings):
     targets = {}
     for fcurve in blender_action.fcurves:
+        # In some invalid files, channel hasn't any keyframes ... this channel need to be ignored
+        if len(fcurve.keyframe_points) == 0:
+            continue
         try:
             target_property = get_target_property_name(fcurve.data_path)
         except:

io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_sampler_keyframes.py

@@ -181,6 +181,8 @@ def gather_keyframes(blender_object_if_armature: typing.Optional[bpy.types.Objec
     else:
         # Just use the keyframes as they are specified in blender
         frames = [keyframe.co[0] for keyframe in channels[0].keyframe_points]
+        # some weird files have duplicate frame at same time, removed them
+        frames = sorted(set(frames))
         for i, frame in enumerate(frames):
             key = Keyframe(channels, frame, bake_channel)
             # key.value = [c.keyframe_points[i].co[0] for c in action_group.channels]