python: expose scenetools.filter_objects().

doc/python/magnum.scenetools.rst

@@ -35,6 +35,10 @@
     :raise AssertionError: If size of any array in :p:`entries_to_keep` does
         not match :ref:`trade.SceneData.field_size()` for given field
 
+.. py:function:: magnum.scenetools.filter_objects
+    :raise AssertionError: If size of :p:`objects_to_keep` is different than
+        :ref:`trade.SceneData.mapping_bound`
+
 .. py:function:: magnum.scenetools.absolute_field_transformations2d
     :raise KeyError: If :p:`field` does not exist in :p:`scene`
     :raise IndexError: If :p:`field_id` negative or not less than

src/python/magnum/scenetools.cpp

@@ -150,6 +150,17 @@ void scenetools(py::module_& m) {
 
             return SceneTools::filterFieldEntries(scene, entriesToKeep);
         }, "Filter individual entries of fields in a scene", py::arg("scene"), py::arg("entries_to_keep"))
+        .def("filter_objects", [](const Trade::SceneData& scene, const Containers::BitArrayView objectsToKeep) {
+            if(objectsToKeep.size() != scene.mappingBound()) {
+                PyErr_Format(PyExc_AssertionError, "expected %llu bits but got %zu", scene.mappingBound(), objectsToKeep.size());
+                throw py::error_already_set{};
+            }
+            /** @todo this will blow up if any objects have a bit / string
+                field, implement that already so it's not needed to check
+                here */
+
+            return SceneTools::filterObjects(scene, objectsToKeep);
+        }, "Filter objects in a scene", py::arg("scene"), py::arg("objects_to_keep"))
         .def("absolute_field_transformations2d", [](const Trade::SceneData& scene, Trade::SceneField field, const Matrix3& globalTransformation) {
             const Containers::Optional<UnsignedInt> fieldId = scene.findFieldId(field);
             if(!fieldId) {

src/python/magnum/test/test_scenetools.py

@@ -274,6 +274,44 @@ class Filter(unittest.TestCase):
                 (importer.scene_field_for_name('yes'), containers.BitArray.value_init(2))
             ])
 
+    def test_objects(self):
+        importer = trade.ImporterManager().load_and_instantiate('GltfImporter')
+        importer.open_file(os.path.join(os.path.dirname(__file__), "scene.gltf"))
+
+        scene = importer.scene(0)
+        scene_refcount = sys.getrefcount(scene)
+        self.assertEqual(scene.mapping_bound, 4)
+        self.assertEqual(scene.field_count, 8)
+        self.assertEqual(scene.field_size(trade.SceneField.PARENT), 4)
+        self.assertEqual(scene.field_size(trade.SceneField.TRANSFORMATION), 4)
+        self.assertEqual(scene.field_size(trade.SceneField.TRANSLATION), 3)
+        self.assertEqual(scene.field_size(trade.SceneField.CAMERA), 2)
+
+        # Two parents, transformations and translations gone
+        objects_to_keep = containers.BitArray.direct_init(scene.mapping_bound, True)
+        objects_to_keep[0] = False
+        objects_to_keep[1] = False
+
+        filtered = scenetools.filter_objects(scene, objects_to_keep)
+        self.assertEqual(filtered.mapping_bound, 4)
+        self.assertEqual(filtered.field_count, 8)
+        self.assertEqual(filtered.field_size(trade.SceneField.PARENT), 2)
+        self.assertEqual(filtered.field_size(trade.SceneField.TRANSFORMATION), 2)
+        self.assertEqual(filtered.field_size(trade.SceneField.TRANSLATION), 1)
+        self.assertEqual(filtered.field_size(trade.SceneField.CAMERA), 2)
+        # The original scene isn't referenced by this one, it's a full copy
+        self.assertEqual(sys.getrefcount(scene), scene_refcount)
+
+    def test_objects_invalid_size(self):
+        importer = trade.ImporterManager().load_and_instantiate('GltfImporter')
+        importer.open_file(os.path.join(os.path.dirname(__file__), "scene.gltf"))
+
+        scene = importer.scene(0)
+        self.assertEqual(scene.mapping_bound, 4)
+
+        with self.assertRaisesRegex(AssertionError, "expected 4 bits but got 3"):
+            scenetools.filter_objects(scene, containers.BitArray.value_init(3))
+
 class Hierarchy(unittest.TestCase):
     def test_absolute_field_transformations2d(self):
         # Static builds with non-static plugins cause assertions with non-owned