Initial commit of glTF 2.0 importer/exporter

Official Khronos Group Blender glTF 2.0 importer and exporter.

glTF specification: https://github.com/KhronosGroup/glTF
The upstream repository can be found here:
https://github.com/KhronosGroup/glTF-Blender-IO

Reviewed By: Bastien, Campbell

Differential Revision: https://developer.blender.org/D3929

1 files changed, 60 insertions, 0 deletions

diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_cache.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_cache.py
new file mode 100755
index 00000000..5b00a98b
--- /dev/null
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_cache.py
@@ -0,0 +1,60 @@
+# Copyright 2018 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 functools
+
+
+def cached(func):
+    """
+    Decorate the cache gather functions results.
+
+    The gather function is only executed if its result isn't in the cache yet
+    :param func: the function to be decorated. It will have a static __cache member afterwards
+    :return:
+    """
+    @functools.wraps(func)
+    def wrapper_cached(*args, **kwargs):
+        assert len(args) >= 2 and 0 <= len(kwargs) <= 1, "Wrong signature for cached function"
+        cache_key_args = args
+        # make a shallow copy of the keyword arguments so that 'export_settings' can be removed
+        cache_key_kwargs = dict(kwargs)
+        if kwargs.get("export_settings"):
+            export_settings = kwargs["export_settings"]
+            # 'export_settings' should not be cached
+            del cache_key_kwargs["export_settings"]
+        else:
+            export_settings = args[-1]
+            cache_key_args = args[:-1]
+
+        # we make a tuple from the function arguments so that they can be used as a key to the cache
+        cache_key = tuple(cache_key_args + tuple(cache_key_kwargs.values()))
+
+        # invalidate cache if export settings have changed
+        if not hasattr(func, "__export_settings") or export_settings != func.__export_settings:
+            func.__cache = {}
+            func.__export_settings = export_settings
+        # use or fill cache
+        if cache_key in func.__cache:
+            return func.__cache[cache_key]
+        else:
+            result = func(*args)
+            func.__cache[cache_key] = result
+            return result
+    return wrapper_cached
+
+
+# TODO: replace "cached" with "unique" in all cases where the caching is functional and not only for performance reasons
+call_or_fetch = cached
+unique = cached
+