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

PiperOrigin-RevId: 881488083
Change-Id: I3aa1c0562bf2fd27057b8056048e3156fc1b067c

doc/APIreference/functions.rst

@@ -4580,6 +4580,15 @@ Find and get utilities
 
 Get spec from body.
 
+.. _mjs_getCompiler:
+
+`mjs_getCompiler <#mjs_getCompiler>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mjs_getCompiler
+
+Get compiler associated with element's origin spec.
+
 .. _mjs_findSpec:
 
 `mjs_findSpec <#mjs_findSpec>`__

doc/changelog.rst

@@ -15,6 +15,9 @@ General
      ``ten_J_colind`` have been moved from :ref:`mjData` to :ref:`mjModel` and are no longer computed at run time by
      ``mj_tendon`` but at compile time.
 
+- Added :ref:`mjs_getCompiler` C API function and a ``compiler`` read-only property to all Python spec element types.
+  This allows querying the compiler settings (e.g., ``meshdir``) from any element, with the correct originating spec's
+  compiler preserved after attachment.
 - Added a new ``strain`` :ref:`equality constraint<flexcomp-edge-equality>` type for trilinear and quadratic
   :ref:`dofs<body-flexcomp-dof>`.
 - Flexes now support collisions with SDF geoms.

doc/includes/references.h

@@ -3643,6 +3643,7 @@ mjsTexture* mjs_addTexture(mjSpec* s);
 mjsMaterial* mjs_addMaterial(mjSpec* s, const mjsDefault* def);
 int mjs_makeMesh(mjsMesh* mesh, mjtMeshBuiltin builtin, double* params, int nparams);
 mjSpec* mjs_getSpec(mjsElement* element);
+mjsCompiler* mjs_getCompiler(mjsElement* element);
 mjSpec* mjs_findSpec(mjSpec* spec, const char* name);
 mjsBody* mjs_findBody(mjSpec* s, const char* name);
 mjsElement* mjs_findElement(mjSpec* s, mjtObj type, const char* name);

include/mujoco/mujoco.h

@@ -1734,6 +1734,9 @@ MJAPI int mjs_makeMesh(mjsMesh* mesh, mjtMeshBuiltin builtin, double* params, in
 // Get spec from body.
 MJAPI mjSpec* mjs_getSpec(mjsElement* element);
 
+// Get compiler associated with element's origin spec.
+MJAPI mjsCompiler* mjs_getCompiler(mjsElement* element);
+
 // Find spec (model asset) by name.
 MJAPI mjSpec* mjs_findSpec(mjSpec* spec, const char* name);
 

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'}

src/user/user_api.cc

@@ -1074,6 +1074,12 @@ mjSpec* mjs_getSpec(mjsElement* element) {
 
 
 
+mjsCompiler* mjs_getCompiler(mjsElement* element) {
+  return static_cast<mjCBase*>(element)->compiler;
+}
+
+
+
 // find spec (model asset) by name
 mjSpec* mjs_findSpec(mjSpec* s, const char* name) {
   mjCModel* model = static_cast<mjCModel*>(s->element);

wasm/codegen/generated/bindings.cc

@@ -9668,6 +9668,14 @@ std::optional<MjsElement> mjs_firstElement_wrapper(MjSpec& s, mjtObj type) {
   return MjsElement(result);
 }
 
+std::optional<MjsCompiler> mjs_getCompiler_wrapper(MjsElement& element) {
+  mjsCompiler* result = mjs_getCompiler(element.get());
+  if (result == nullptr) {
+    return std::nullopt;
+  }
+  return MjsCompiler(result);
+}
+
 std::optional<MjsDefault> mjs_getDefault_wrapper(MjsElement& element) {
   mjsDefault* result = mjs_getDefault(element.get());
   if (result == nullptr) {
@@ -13191,6 +13199,7 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
   function("mjs_findSpec", &mjs_findSpec_wrapper);
   function("mjs_firstChild", &mjs_firstChild_wrapper);
   function("mjs_firstElement", &mjs_firstElement_wrapper);
+  function("mjs_getCompiler", &mjs_getCompiler_wrapper);
   function("mjs_getDefault", &mjs_getDefault_wrapper);
   function("mjs_getError", &mjs_getError_wrapper);
   function("mjs_getFrame", &mjs_getFrame_wrapper);