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/tools/ingest_tree.py

@@ -1,8 +1,8 @@
 """Import Poly Haven island_tree_01 and export decimated GLBs.
 
-Each output GLB contains exactly one tree variant (1 branch mesh + 1 leaf
-mesh) with shared material references so the main generator can instance them
-the same way it instances grass tufts.
+Each output GLB is a single tree variant (branch + leaf) with shared
+material references. This is the offline ingest tool; the runtime module
+(osmassets/tree.py) loads directly from the vendored .blend via wm.append.
 """
 
 import math
@@ -13,14 +13,18 @@ import bpy
 
 
 TREE_BLEND = os.path.join(
-    os.path.dirname(__file__), "..", "..",
+    os.path.dirname(os.path.abspath(__file__)), "..", "..",
     "assets", "models", "polyhaven", "island_tree_01",
     "island_tree_01_1k.blend",
 )
 
+# Target triangle counts for the decimated per-tree mesh.
+# LOD1 branches are 135-570 tris, LOD1 leaves 380-1531 tris.
+# 180 + 220 = 400 per tree, on par with the procedural trees.
 TARGET_BRANCH_TRIS = 180
 TARGET_LEAF_TRIS = 220
 
+# Branch / leaf LOD1 pairings for the four variants.
 PAIRS = [("a", "b"), ("b", "a"), ("c", "a"), ("d", "b")]
 
 
@@ -40,11 +44,13 @@ def cli_args():
 
 
 def decimate_to_target(obj, target_tris):
+    """Decimate a mesh to roughly target_tris, return new mesh datablock."""
     source = obj.data
     source.calc_loop_triangles()
     source_tris = len(source.loop_triangles)
     if source_tris <= target_tris:
         return source.copy()
+
     modifier = obj.modifiers.new("TreeDecimate", "DECIMATE")
     modifier.ratio = max(0.05, target_tris / source_tris)
     bpy.context.view_layer.update()
@@ -56,10 +62,7 @@ def decimate_to_target(obj, target_tris):
 
 
 def export_one(out_path, b_mesh, l_mesh, materials):
-    """Export a single tree variant to a clean GLB.
-
-    Works in a fresh, empty scene so nothing from the source blend leaks in.
-    """
+    """Export a single tree variant to a clean GLB in a fresh temp scene."""
     scene = bpy.data.scenes.new("_TreeIngest")
     bpy.context.window.scene = scene
     col = bpy.data.collections.new("_Tree")
@@ -104,6 +107,7 @@ def main():
     branch_mat = bpy.data.materials.get("island_tree_01_branches")
     leaf_mat = bpy.data.materials.get("island_tree_01_leaves")
     if not branch_mat or not leaf_mat:
+        print("Missing materials in source blend")
         return 1
 
     decimated = []
@@ -113,6 +117,7 @@ def main():
         leaf_obj = bpy.data.objects.get(
             f"island_tree_01_leaves_{leaf_id}_LOD1")
         if not branch_obj or not leaf_obj:
+            print(f"Skipping variant {vi}: missing LOD1 objects")
             continue
 
         b_mesh = decimate_to_target(branch_obj, TARGET_BRANCH_TRIS)