Add mjs_getCompiler C API and compiler property to Python spec elements.

PiperOrigin-RevId: 881488083
Change-Id: I3aa1c0562bf2fd27057b8056048e3156fc1b067c

python/mujoco/codegen/generate_spec_bindings.py

@@ -947,6 +947,24 @@ def generate_name() -> None:
     print(code)
 
 
+def generate_compiler() -> None:
+  """Generate compiler property for all spec element types."""
+  for key, _, _, _, _ in SPECS:
+    elem = key.removeprefix('mjs')
+    titlecase = 'Mjs' + elem
+    code = f"""\n
+      {key}.def_property_readonly("compiler",
+      [](raw::{titlecase}& self) -> raw::MjsCompiler& {{
+        ::mjsCompiler* compiler = mjs_getCompiler(self.element);
+        if (!compiler) {{
+          throw pybind11::value_error("Element is not attached to a spec.");
+        }}
+        return *compiler;
+      }}, py::return_value_policy::reference_internal);
+    """
+    print(code)
+
+
 def main(argv: Sequence[str]) -> None:
   if len(argv) > 1:
     raise app.UsageError('Too many command-line arguments.')
@@ -956,6 +974,7 @@ def main(argv: Sequence[str]) -> None:
   generate_signature()
   generate_id()
   generate_name()
+  generate_compiler()
 
 
 if __name__ == '__main__':

python/mujoco/introspect/functions.py

@@ -10823,6 +10823,22 @@ FUNCTIONS: Mapping[str, FunctionDecl] = dict([
          ),
          doc='Get spec from body.',
      )),
+    ('mjs_getCompiler',
+     FunctionDecl(
+         name='mjs_getCompiler',
+         return_type=PointerType(
+             inner_type=ValueType(name='mjsCompiler'),
+         ),
+         parameters=(
+             FunctionParameterDecl(
+                 name='element',
+                 type=PointerType(
+                     inner_type=ValueType(name='mjsElement'),
+                 ),
+             ),
+         ),
+         doc="Get compiler associated with element's origin spec.",
+     )),
     ('mjs_findSpec',
      FunctionDecl(
          name='mjs_findSpec',

python/mujoco/specs_test.py

@@ -1188,6 +1188,36 @@ class SpecsTest(absltest.TestCase):
     model = parent.compile()
     np.testing.assert_almost_equal(model.body_quat[1], [1, 0, 0, 0])
 
+  def test_compiler_from_element(self):
+    child = mujoco.MjSpec()
+    child.meshdir = '/child/meshes'
+    child.texturedir = '/child/textures'
+    child_body = child.worldbody.add_body()
+    child_geom = child_body.add_geom()
+    child_geom.size[0] = 1
+    child_site = child_body.add_site()
+
+    parent = mujoco.MjSpec()
+    parent.meshdir = '/parent/meshes'
+    parent.texturedir = '/parent/textures'
+    parent_geom = parent.worldbody.add_geom()
+    parent_geom.size[0] = 1
+    parent_site = parent.worldbody.add_site()
+
+    self.assertEqual(parent_geom.compiler.meshdir, '/parent/meshes')
+    self.assertEqual(parent_geom.compiler.texturedir, '/parent/textures')
+    self.assertEqual(child_geom.compiler.meshdir, '/child/meshes')
+    self.assertEqual(child_site.compiler.meshdir, '/child/meshes')
+
+    frame = parent.worldbody.add_frame()
+    frame.attach_body(child_body, prefix='child-')
+
+    self.assertEqual(parent_geom.compiler.meshdir, '/parent/meshes')
+    self.assertEqual(parent_site.compiler.meshdir, '/parent/meshes')
+    self.assertEqual(child_geom.compiler.meshdir, '/child/meshes')
+    self.assertEqual(child_geom.compiler.texturedir, '/child/textures')
+    self.assertEqual(child_site.compiler.meshdir, '/child/meshes')
+
   def test_attach_to_site(self):
     parent = mujoco.MjSpec()
     parent.assets = {'path/cube.obj': 'cube_content'}