glTF exporter: Various enhancements:

* reconect the double-sided flag from the old custom node system
* remove empty texture transform extensions
* Export of non-number array of custom properties

io_scene_gltf2/blender/exp/gltf2_blender_gather_material_normal_texture_info_class.py

@@ -67,6 +67,8 @@ def __gather_extensions(blender_shader_sockets_or_texture_slots, export_settings
 
     texture_node = texture_socket.links[0].from_node
     texture_transform = gltf2_blender_get.get_texture_transform_from_texture_node(texture_node)
+    if texture_transform is None:
+        return None
 
     extension = Extension("KHR_texture_transform", texture_transform)
     return {"KHR_texture_transform": extension}

io_scene_gltf2/blender/exp/gltf2_blender_gather_materials.py

@@ -88,6 +88,11 @@ def __gather_alpha_mode(blender_material, export_settings):
 
 
 def __gather_double_sided(blender_material, export_settings):
+    old_double_sided_socket = gltf2_blender_get.get_socket_or_texture_slot_old(blender_material, "DoubleSided")
+    if old_double_sided_socket is not None and\
+            not old_double_sided_socket.is_linked and\
+            old_double_sided_socket.default_value > 0.5:
+        return True
     return None
 
 

io_scene_gltf2/blender/exp/gltf2_blender_generate_extras.py

@@ -32,28 +32,9 @@ def generate_extras(blender_element):
         if custom_property in black_list:
             continue
 
-        value = blender_element[custom_property]
+        value = __to_json_compatible(blender_element[custom_property])
 
-        add_value = False
-
-        if isinstance(value, bpy.types.ID):
-            add_value = True
-
-        if isinstance(value, str):
-            add_value = True
-
-        if isinstance(value, (int, float)):
-            add_value = True
-
-        if hasattr(value, "to_list"):
-            value = value.to_list()
-            add_value = True
-
-        if hasattr(value, "to_dict"):
-            value = value.to_dict()
-            add_value = gltf2_blender_json.is_json_convertible(value)
-
-        if add_value:
+        if value is not None:
             extras[custom_property] = value
             count += 1
 
@@ -62,3 +43,36 @@ def generate_extras(blender_element):
 
     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 gltf2_blender_json.is_json_convertible(value):
+            return value
+
+    return None
+

io_scene_gltf2/blender/exp/gltf2_blender_get.py

@@ -372,6 +372,9 @@ def get_texture_transform_from_texture_node(texture_node):
     if texture_transform["rotation"] == 0:
         del(texture_transform["rotation"])
 
+    if len(texture_transform) == 0:
+        return None
+
     return texture_transform