Support datablocks used as default values in nodes

Follow pointers of input sockets of nodes that can reference ID datablocks.

CHANGELOG.md

@@ -6,6 +6,7 @@ changed functionality, fixed bugs).
 ## Version 1.6 (in development)
 
 - Support linked collections used as input in a Geometry Nodes modifier.
+- Support collections, objects, images, and textures used as default values in nodes.
 
 
 ## Version 1.5.1 (2021-07-22)

blender_asset_tracer/cdefs.py

@@ -72,6 +72,23 @@ IDP_DOUBLE = 8
 IDP_IDPARRAY = 9
 IDP_NUMTYPES = 10
 
+# DNA_node_types.h
+SOCK_CUSTOM = -1  # socket has no integer type
+SOCK_FLOAT = 0
+SOCK_VECTOR = 1
+SOCK_RGBA = 2
+SOCK_SHADER = 3
+SOCK_BOOLEAN = 4
+SOCK_MESH = 5  # deprecated
+SOCK_INT = 6
+SOCK_STRING = 7
+SOCK_OBJECT = 8
+SOCK_IMAGE = 9
+SOCK_GEOMETRY = 10
+SOCK_COLLECTION = 11
+SOCK_TEXTURE = 12
+SOCK_MATERIAL = 13
+
 # BKE_pointcache.h
 PTCACHE_FILE_PTCACHE = 0
 PTCACHE_FILE_OPENVDB = 1

blender_asset_tracer/trace/expanders.py

@@ -93,15 +93,35 @@ def _expand_generic_nodetree(block: blendfile.BlendFileBlock):
     assert block.dna_type.dna_type_id == b"bNodeTree"
 
     nodes = block.get_pointer((b"nodes", b"first"))
+
+    # See DNA_node_types.h
+    socket_types_with_value_pointer = {
+        cdefs.SOCK_OBJECT,  #  bNodeSocketValueObject
+        cdefs.SOCK_IMAGE,  #  bNodeSocketValueImage
+        cdefs.SOCK_COLLECTION,  #  bNodeSocketValueCollection
+        cdefs.SOCK_TEXTURE,  #  bNodeSocketValueTexture
+        cdefs.SOCK_MATERIAL,  #  bNodeSocketValueMaterial
+    }
+
     for node in iterators.listbase(nodes):
         if node[b"type"] == cdefs.CMP_NODE_R_LAYERS:
             continue
-        yield node
 
         # The 'id' property points to whatever is used by the node
         # (like the image in an image texture node).
         yield node.get_pointer(b"id")
 
+        # Default values of inputs can also point to ID datablocks.
+        inputs = node.get_pointer((b"inputs", b"first"))
+        for input in iterators.listbase(inputs):
+            if input[b"type"] not in socket_types_with_value_pointer:
+                continue
+            value_container = input.get_pointer(b"default_value")
+            if not value_container:
+                continue
+            value = value_container.get_pointer(b"value")
+            yield value
+
 
 def _expand_generic_idprops(block: blendfile.BlendFileBlock):
     """Yield ID datablocks and their libraries referenced from ID properties."""

tests/test_tracer.py

@@ -464,6 +464,34 @@ class DepsTest(AbstractTracerTest):
             },
         )
 
+    def test_geometry_nodes_node_input(self):
+        """Test linked collection as input to a geom node.
+
+        Here a Geometry Nodes node references a collection that is not instanced
+        into the scene, which caused it to be missed.
+        """
+        self.assert_deps(
+            "geometry-nodes-3/shot_file.blend",
+            {
+                b"LIset_file.blend": Expect(
+                    type="Library",
+                    full_field="name[1024]",
+                    dirname_field=None,
+                    basename_field=None,
+                    asset_path=b"//set_file.blend",
+                    is_sequence=False,
+                ),
+                b"LIlib_trash.blend": Expect(
+                    type="Library",
+                    full_field="name[1024]",
+                    dirname_field=None,
+                    basename_field=None,
+                    asset_path=b"//lib_trash.blend",
+                    is_sequence=False,
+                ),
+            },
+        )
+
     def test_usage_abspath(self):
         deps = [
             dep