converter: Add flatten_nodes option

This option attempts to optimize the node tree and remove unneeded
nodes. This will generate a different hierarchy than the input glTF
file, so it is off by default.

Fixes #101

gltf/cli.py

@@ -90,6 +90,12 @@ def main():
         help='control what to do with animation data'
     )
 
+    parser.add_argument(
+        '--flatten-nodes',
+        action='store_true',
+        help='attempt to flatten resulting node structure'
+    )
+
     args = parser.parse_args()
 
     settings = gltf.GltfSettings(
@@ -99,6 +105,7 @@ def main():
         textures=args.textures,
         legacy_materials=args.legacy_materials,
         skip_animations=args.animations == 'skip',
+        flatten_nodes=args.flatten_nodes,
     )
 
     src = p3d.Filename(args.src)

gltf/converter.py

@@ -32,6 +32,7 @@ class GltfSettings:
     textures: str = 'ref'
     legacy_materials: bool = False
     skip_animations: bool = False
+    flatten_nodes: bool = False
 
 
 class Converter():
@@ -378,6 +379,9 @@ def visible_recursive(node, visible):
             for nodeid in node_list:
                 add_node(scene_root, gltf_scene, nodeid, {}, {})
 
+            if self.settings.flatten_nodes:
+                scene_root.flatten_medium()
+
             self.scenes[sceneid] = scene_root
 
         # Set the active scene

tests/conftest.py

@@ -2,6 +2,24 @@
 
 import pytest
 import panda3d.core as p3d
+from direct.showbase.ShowBase import ShowBase
+
+@pytest.fixture(scope='session')
+def showbase():
+    prcdata = (
+        'window-type none\n'
+        'audio-library-name null\n'
+        'model-cache-dir\n'
+    )
+    p3d.load_prc_file_data('', prcdata)
+    base = ShowBase()
+
+    type_registry = p3d.LoaderFileTypeRegistry.get_global_ptr()
+    ftype = type_registry.get_type_from_extension('gltf')
+    assert ftype.getName() == 'Python loader'
+
+    return base
+
 
 @pytest.fixture
 def modelroot():

tests/test_cli.py

@@ -2,6 +2,9 @@
 import subprocess
 
 
+import panda3d.core as p3d
+
+
 def test_cli_basic(modelroot, tmp_path):
     src = (modelroot / 'BoxTextured.gltf').to_os_specific()
     dst = tmp_path / 'tmp.bam'
@@ -26,3 +29,22 @@ def test_cli_copy_textures(modelroot, tmp_path):
 
     assert os.path.exists(dst)
     assert os.path.exists(tmp_path / 'CesiumLogoFlat.png')
+
+def test_cli_flatten_nodes(modelroot, tmp_path, showbase):
+    # Load showbase to ensure using the loader does not mess with the type registry
+    assert showbase
+
+    src = (modelroot / 'Fox.glb').to_os_specific()
+    dst = tmp_path / 'tmp.bam'
+    subprocess.check_call([
+        'gltf2bam',
+        '--flatten-nodes',
+        src,
+        dst,
+    ])
+
+    loader = p3d.Loader.get_global_ptr()
+    scene = p3d.NodePath(loader.load_sync(dst, p3d.LoaderOptions.LF_no_cache))
+
+    panda_nodes = scene.find_all_matches('**/*/-PandaNode')
+    assert not panda_nodes

tests/test_load.py

@@ -1,26 +1,8 @@
 import panda3d.core as p3d
-from direct.showbase.ShowBase import ShowBase
 import pytest #pylint:disable=wrong-import-order
 
-#pylint:disable=redefined-outer-name
-
-
-@pytest.fixture(scope='session')
-def showbase():
-    prcdata = (
-        'window-type none\n'
-        'audio-library-name null\n'
-        'model-cache-dir\n'
-    )
-    p3d.load_prc_file_data('', prcdata)
-    base = ShowBase()
-
-    type_registry = p3d.LoaderFileTypeRegistry.get_global_ptr()
-    ftype = type_registry.get_type_from_extension('gltf')
-    assert ftype.getName() == 'Python loader'
-
-    return base
 
+#pylint:disable=redefined-outer-name
 @pytest.fixture
 def modelpath(modelroot):
     return p3d.Filename(modelroot, 'test.gltf')