docs: tree.py + ingest_tree.py 补充文档注释

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

blender/osmassets/tree.py

@@ -1,10 +1,14 @@
 """Import Poly Haven island_tree_01 as instanced-tree asset.
 
-This is the analog of load_tuft_variants() for trees.  It appends only the
-LOD1 meshes from the vendored .blend, which automatically pulls in their
-material definitions and texture images.  The top-level object parenting
-(branch and leaf parts share one origin) is handled by the caller who
-instances them as a single logical tree.
+The runtime counterpart to blender/tools/ingest_tree.py.  Instead of exporting
+pre-baked GLBs (which would duplicate textures), this module appends the
+vendored .blend at scene-build time.  The appended objects pull in their
+material datablocks and texture images automatically — the textures live next
+to the .blend and are resolved via relative paths.
+
+load_tree_variants() is the analog of load_tuft_variants() for trees: import
+once, copy the meshes, remove the imported objects, return mesh datablocks
+ready for instancing.
 """
 
 import os
@@ -19,36 +23,33 @@ TREE_BLEND = os.path.join(
 )
 
 # Branch / leaf LOD1 pairings for the four variants.
-# Each pairing is a single logical tree that the caller instances as one.
+# Each pairing is one logical tree that the caller instances as a unit.
 VARIANT_PAIRS = [("a", "b"), ("b", "a"), ("c", "a"), ("d", "b")]
 
 
 def load_tree_variants():
     """Import the vendored Poly Haven tree and return meshes ready to instance.
 
-    Returns a list of (branch_mesh, leaf_mesh) tuples, one per variant.  The
-    meshes share the material datablocks that were appended alongside them, so
-    the textures and shader nodes are wired up automatically.
+    Returns a list of (branch_mesh, leaf_mesh) tuples, one per variant.
+    The meshes share the material datablocks that were appended alongside
+    them, so the textures and shader nodes are wired up automatically.
 
-    Returns [] when the source .blend is absent so a clean checkout still
-    builds.  The caller falls back to procedural trees.
+    Returns [] when the source .blend is absent — the caller falls back to
+    procedural trees so a clean checkout still builds.
     """
     if not os.path.exists(TREE_BLEND):
         return []
 
     before_objects = set(bpy.data.objects)
-    before_meshes = set(bpy.data.meshes)
 
-    # Gather the object names we need from the library.
+    # Append one object at a time: bpy.ops.wm.append with a multi-file list
+    # can crash when objects in the same library share data that was already
+    # linked by an earlier append in the same batch.
     wanted = []
     for branch_id, leaf_id in VARIANT_PAIRS:
         wanted.append(f"island_tree_01_branches_{branch_id}_LOD1")
         wanted.append(f"island_tree_01_leaves_{leaf_id}_LOD1")
 
-    # bpy.ops.wm.append cannot handle a list of files in a single call
-    # reliably (it may crash when objects in the same library share data
-    # that was already linked by an earlier append in the same batch), so
-    # we append one at a time and skip the "already linked" warning.
     for name in wanted:
         try:
             bpy.ops.wm.append(
@@ -59,22 +60,12 @@ def load_tree_variants():
             )
         except RuntimeError:
             # Object already linked by an earlier append of a sibling mesh
-            # that shared materials; this is expected and harmless.
+            # that shared materials; harmless.
             pass
 
     imported = [obj for obj in set(bpy.data.objects) - before_objects
                 if obj.type == "MESH"]
 
-    # Pair branch + leaf into variants.  We append in the order above so
-    # a simple zip works.
-    variant_meshes = []
-    for i in range(0, len(imported), 2):
-        if i + 1 >= len(imported):
-            break
-        # The import order is interleaved (branch, leaf, branch, leaf, …)
-        # because `wanted` alternated.  Sort by name to be safe.
-        pass
-
     # Rebuild the pairs from the imported object names.
     variants = []
     for branch_id, leaf_id in VARIANT_PAIRS:
@@ -105,10 +96,12 @@ def load_tree_variants():
 def assemble(positions, collection):
     """Place island_tree_01 instances at `positions`.
 
-    positions is a list of (x, y, height) tuples.  Returns the number of
-    trees placed (0 when the model is unavailable).
+    positions is a list of (x, y, height) tuples as gathered by the two
+    tree-collecting loops (point nodes + tree_row samples).
+
+    Returns the number of trees placed (0 when the model is unavailable).
     """
-    import math  # noqa — tree.py has no top-level math import by design
+    import math  # noqa — tree.py has no top-level math import otherwise
 
     variants = load_tree_variants()
     if not variants: