From 32e08f9507c9bdc5a1a5411c6fa9f0346542b038 Mon Sep 17 00:00:00 2001
From: Sam Haves <shaves@google.com>
Date: Thu, 2 Oct 2025 08:52:50 -0700
Subject: [PATCH] Expose userfacenormal to mjsMesh

PiperOrigin-RevId: 814253177
Change-Id: I644974feea0722f03e7c3b01be7b702dba233f0a
---
 doc/includes/references.h           | 1 +
 include/mujoco/mjspec.h             | 1 +
 python/mujoco/introspect/structs.py | 7 +++++++
 src/user/user_mesh.cc               | 2 ++
 4 files changed, 11 insertions(+)

diff --git a/doc/includes/references.h b/doc/includes/references.h
index 4a2344f3..80a8e766 100644
--- a/doc/includes/references.h
+++ b/doc/includes/references.h
@@ -2149,6 +2149,7 @@ typedef struct mjsMesh_ {          // mesh specification
   mjFloatVec* usernormal;          // user normal data
   mjFloatVec* usertexcoord;        // user texcoord data
   mjIntVec* userface;              // user vertex indices
+  mjIntVec* userfacenormal;        // user face normal indices
   mjIntVec* userfacetexcoord;      // user texcoord indices
   mjsPlugin plugin;                // sdf plugin
   mjString* material;              // name of material
diff --git a/include/mujoco/mjspec.h b/include/mujoco/mjspec.h
index eba3a66a..e84f5f33 100644
--- a/include/mujoco/mjspec.h
+++ b/include/mujoco/mjspec.h
@@ -479,6 +479,7 @@ typedef struct mjsMesh_ {          // mesh specification
   mjFloatVec* usernormal;          // user normal data
   mjFloatVec* usertexcoord;        // user texcoord data
   mjIntVec* userface;              // user vertex indices
+  mjIntVec* userfacenormal;        // user face normal indices
   mjIntVec* userfacetexcoord;      // user texcoord indices
   mjsPlugin plugin;                // sdf plugin
   mjString* material;              // name of material
diff --git a/python/mujoco/introspect/structs.py b/python/mujoco/introspect/structs.py
index 988a54ef..5d187cf3 100644
--- a/python/mujoco/introspect/structs.py
+++ b/python/mujoco/introspect/structs.py
@@ -9378,6 +9378,13 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  ),
                  doc='user vertex indices',
              ),
+             StructFieldDecl(
+                 name='userfacenormal',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjIntVec'),
+                 ),
+                 doc='user face normal indices',
+             ),
              StructFieldDecl(
                  name='userfacetexcoord',
                  type=PointerType(
diff --git a/src/user/user_mesh.cc b/src/user/user_mesh.cc
index 18d5db0a..9a69b2d6 100644
--- a/src/user/user_mesh.cc
+++ b/src/user/user_mesh.cc
@@ -277,6 +277,7 @@ void mjCMesh::PointToLocal() {
   spec.uservert = &spec_vert_;
   spec.usernormal = &spec_normal_;
   spec.userface = &spec_face_;
+  spec.userfacenormal = &spec_facenormal_;
   spec.usertexcoord = &spec_texcoord_;
   spec.userfacetexcoord = &spec_facetexcoord_;
   spec.material = &spec_material_;
@@ -288,6 +289,7 @@ void mjCMesh::PointToLocal() {
   uservert = nullptr;
   usernormal = nullptr;
   userface = nullptr;
+  userfacenormal = nullptr;
   usertexcoord = nullptr;
   userfacetexcoord = nullptr;
 }