upright_sprite: Fix walk animation in first person (minetest#12194)

src/client/content_cao.cpp

@@ -1974,20 +1974,17 @@ void GenericCAO::updateMeshCulling()
 
  const bool hidden = m_client->getCamera()->getCameraMode() == CAMERA_MODE_FIRST;
 
- if (m_meshnode && m_prop.visual == "upright_sprite") {
- u32 buffers = m_meshnode->getMesh()->getMeshBufferCount();
- for (u32 i = 0; i < buffers; i++) {
- video::SMaterial &mat = m_meshnode->getMesh()->getMeshBuffer(i)->getMaterial();
- // upright sprite has no backface culling
- mat.setFlag(video::EMF_FRONT_FACE_CULLING, hidden);
- }
- return;
- }
-
  scene::ISceneNode *node = getSceneNode();
+
  if (!node)
  return;
 
+ if (m_prop.visual == "upright_sprite") {
+ // upright sprite has no backface culling
+ node->setMaterialFlag(video::EMF_FRONT_FACE_CULLING, hidden);
+ return;
+ }
+
  if (hidden) {
  // Hide the mesh by culling both front and
  // back faces. Serious hackyness but it works for our