Fix assigning bytes to texture data.

PiperOrigin-RevId: 706747323
Change-Id: I6b0ee67d4f35db3a149ba8d9979546d3c712bb8b

python/mujoco/codegen/generate_spec_bindings.py

@@ -170,11 +170,12 @@ def _ptr_binding_code(
         return MjTypeVec<std::byte>(self.{fullvarname}->data(),
                                     self.{fullvarname}->size());
       }},
-    []({rawclassname}& self, py::object rhs) {{
+    []({rawclassname}& self, py::bytes& rhs) {{
         self.{fullvarname}->clear();
         self.{fullvarname}->reserve(py::len(rhs));
-        for (auto val : rhs) {{
-          self.{fullvarname}->push_back(py::cast<const std::byte>(val));
+        std::string_view rhs_view = py::cast<std::string_view>(rhs);
+        for (auto val : rhs_view) {{
+          self.{fullvarname}->push_back(static_cast<std::byte>(val));
         }}
     }}, py::return_value_policy::move);"""
   elif vartype == 'mjStringVec':

python/mujoco/specs_test.py

@@ -891,6 +891,12 @@ class SpecsTest(absltest.TestCase):
     with self.assertRaises(IndexError):
       material.textures[-1] = 'x'
 
+  def test_assign_texture(self):
+    spec = mujoco.MjSpec()
+    texture = spec.add_texture(name='texture', height=2, width=2)
+    texture.data = np.zeros((2, 2, 3), dtype=np.uint8).tobytes()
+    spec.compile()
+
   def test_attach_units(self):
     child = mujoco.MjSpec()
     parent = mujoco.MjSpec()