1 files changed, 91 insertions, 0 deletions
diff --git a/io_scene_gltf2/blender/com/gltf2_blender_extras.py b/io_scene_gltf2/blender/com/gltf2_blender_extras.py
new file mode 100644
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+++ b/io_scene_gltf2/blender/com/gltf2_blender_extras.py
@@ -0,0 +1,91 @@
+# Copyright 2018-2019 The glTF-Blender-IO authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import bpy
+from .gltf2_blender_json import is_json_convertible
+
+
+# Custom properties, which are in most cases present and should not be imported/exported.
+BLACK_LIST = ['cycles', 'cycles_visibility', 'cycles_curves', '_RNA_UI']
+
+
+def generate_extras(blender_element):
+    """Filter and create a custom property, which is stored in the glTF extra field."""
+    if not blender_element:
+        return None
+
+    extras = {}
+
+    for custom_property in blender_element.keys():
+        if custom_property in BLACK_LIST:
+            continue
+
+        value = __to_json_compatible(blender_element[custom_property])
+
+        if value is not None:
+            extras[custom_property] = value
+
+    if not extras:
+        return None
+
+    return extras
+
+
+def __to_json_compatible(value):
+    """Make a value (usually a custom property) compatible with json"""
+
+    if isinstance(value, bpy.types.ID):
+        return value
+
+    elif isinstance(value, str):
+        return value
+
+    elif isinstance(value, (int, float)):
+        return value
+
+    # for list classes
+    elif isinstance(value, list):
+        value = list(value)
+        # make sure contents are json-compatible too
+        for index in range(len(value)):
+            value[index] = __to_json_compatible(value[index])
+        return value
+
+    # for IDPropertyArray classes
+    elif hasattr(value, "to_list"):
+        value = value.to_list()
+        return value
+
+    elif hasattr(value, "to_dict"):
+        value = value.to_dict()
+        if is_json_convertible(value):
+            return value
+
+    return None
+
+
+def set_extras(blender_element, extras, exclude=[]):
+    """Copy extras onto a Blender object."""
+    if not extras or not isinstance(extras, dict):
+        return
+
+    for custom_property, value in extras.items():
+        if custom_property in BLACK_LIST:
+            continue
+        if custom_property in exclude:
+            continue
+
+        blender_element[custom_property] = value
+