From 07a159e553a93411d023aba00277920beb307fdf Mon Sep 17 00:00:00 2001
From: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Date: Sat, 16 May 2026 13:42:29 -0700
Subject: [PATCH] docs: fix marching_cubes return type (unique vertex indices,
 not normals)

Fixes #422

Signed-off-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
---
 fvdb/functional/_meshing.py | 7 +++++--
 fvdb/grid.py                | 4 ++--
 fvdb/grid_batch.py          | 3 ++-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/fvdb/functional/_meshing.py b/fvdb/functional/_meshing.py
index 286ddee03..3affc03f2 100644
--- a/fvdb/functional/_meshing.py
+++ b/fvdb/functional/_meshing.py
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 """Functional API for meshing and TSDF integration on sparse grids."""
+
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
@@ -36,7 +37,8 @@ def marching_cubes_batch(
     Returns:
         vertices (JaggedTensor): Mesh vertex positions, shape ``(B, -1, 3)``.
         faces (JaggedTensor): Triangle face indices.
-        normals (JaggedTensor): Per-vertex normals.
+        unique_vertex_ids (JaggedTensor): Unique vertex IDs with int64 values,
+            shape ``(B, -1, 3)``.
 
     .. seealso:: :func:`marching_cubes_single`
     """
@@ -60,7 +62,8 @@ def marching_cubes_single(
     Returns:
         vertices (torch.Tensor): Mesh vertex positions, shape ``(N, 3)``.
         faces (torch.Tensor): Triangle face indices.
-        normals (torch.Tensor): Per-vertex normals.
+        unique_vertex_ids (torch.Tensor): Unique vertex IDs with dtype ``torch.int64``,
+            shape ``(N, 3)``.
 
     .. seealso:: :func:`marching_cubes_batch`
     """
diff --git a/fvdb/grid.py b/fvdb/grid.py
index 8623a205c..ab2efff4c 100644
--- a/fvdb/grid.py
+++ b/fvdb/grid.py
@@ -1470,8 +1470,8 @@ def marching_cubes(
                 ``(num_vertices, 3)``.
             faces (torch.Tensor): Triangle face indices of shape
                 ``(num_faces, 3)``.
-            normals (torch.Tensor): Vertex normals of shape
-                ``(num_vertices, 3)``.
+            unique_vertex_ids (torch.Tensor): Unique vertex IDs of shape
+                ``(num_vertices, 3)`` and dtype ``torch.int64``.
         """
         from . import functional
 
diff --git a/fvdb/grid_batch.py b/fvdb/grid_batch.py
index 06858bbcb..0d89969c4 100644
--- a/fvdb/grid_batch.py
+++ b/fvdb/grid_batch.py
@@ -1020,7 +1020,8 @@ def marching_cubes(
         Returns:
             vertex_positions (JaggedTensor): Mesh vertex positions. Shape: ``(batch_size, num_vertices_for_grid_b, 3)``.
             face_indices (JaggedTensor): Triangle face indices. Shape: ``(batch_size, num_faces_for_grid_b, 3)``.
-            vertex_normals (JaggedTensor): Vertex normals. Shape: ``(batch_size, num_vertices_for_grid_b, 3)``.
+            unique_vertex_ids (JaggedTensor): Unique vertex IDs with int64 values.
+                Shape: ``(batch_size, num_vertices_for_grid_b, 3)``.
 
         .. seealso:: :meth:`Grid.marching_cubes`
         """