Mujoco_WASM/python/mujoco/specs.cc

// Copyright 2024 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <array>
#include <cstddef>  // IWYU pragma: keep
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <string_view>  // IWYU pragma: keep
#include <unordered_map>
#include <vector>       // IWYU pragma: keep

#include <Eigen/Core>
#include <Eigen/Eigen>
#include <mujoco/mjspec.h>  // IWYU pragma: keep
#include <mujoco/mujoco.h>
#include "errors.h"
#include "indexers.h"  // IWYU pragma: keep
#include "raw.h"
#include "structs.h"  // IWYU pragma: keep
#include <pybind11/cast.h>
#include <pybind11/eigen.h>
#include <pybind11/eigen/matrix.h>
#include <pybind11/pybind11.h>
#include <pybind11/pytypes.h>
#include <pybind11/stl.h>

namespace py = ::pybind11;

namespace mujoco::python {
using MjInt2 = Eigen::Map<Eigen::Vector2i>;
using MjInt3 = Eigen::Map<Eigen::Vector3i>;
using MjFloat2 = Eigen::Map<Eigen::Vector2f>;
using MjFloat3 = Eigen::Map<Eigen::Vector3f>;
using MjFloat4 = Eigen::Map<Eigen::Vector4f>;
using MjDouble2 = Eigen::Map<Eigen::Vector2d>;
using MjDouble3 = Eigen::Map<Eigen::Vector3d>;
using MjDouble4 = Eigen::Map<Eigen::Vector4d>;
using MjDouble5 = Eigen::Map<Eigen::Matrix<double, 5, 1>>;
using MjDouble6 = Eigen::Map<Eigen::Matrix<double, 6, 1>>;
using MjDouble10 = Eigen::Map<Eigen::Matrix<double, 10, 1>>;
using MjDouble11 = Eigen::Map<Eigen::Matrix<double, 11, 1>>;
using MjDoubleVec = Eigen::Map<Eigen::VectorXd>;

using MjIntRef2 = Eigen::Ref<const Eigen::Vector2i>;
using MjIntRef3 = Eigen::Ref<const Eigen::Vector3i>;
using MjFloatRef2 = Eigen::Ref<const Eigen::Vector2f>;
using MjFloatRef3 = Eigen::Ref<const Eigen::Vector3f>;
using MjFloatRef4 = Eigen::Ref<const Eigen::Vector4f>;
using MjDoubleRef2 = Eigen::Ref<const Eigen::Vector2d>;
using MjDoubleRef3 = Eigen::Ref<const Eigen::Vector3d>;
using MjDoubleRef4 = Eigen::Ref<const Eigen::Vector4d>;
using MjDoubleRef5 = Eigen::Ref<const Eigen::Matrix<double, 5, 1>>;
using MjDoubleRef6 = Eigen::Ref<const Eigen::Matrix<double, 6, 1>>;
using MjDoubleRef10 = Eigen::Ref<const Eigen::Matrix<double, 10, 1>>;
using MjDoubleRef11 = Eigen::Ref<const Eigen::Matrix<double, 11, 1>>;
using MjDoubleRefVec = Eigen::Ref<const Eigen::VectorXd>;

struct MjSpec {
  MjSpec() : ptr(mj_makeSpec()) {}
  MjSpec(raw::MjSpec* ptr) : ptr(ptr) {}

  // copy constructor and assignment
  MjSpec(const MjSpec& other) : ptr(mj_copySpec(other.ptr)) {}
  MjSpec& operator=(const MjSpec& other) {
    ptr = mj_copySpec(other.ptr);
    return *this;
  }

  // move constructor and move assignment
  MjSpec(MjSpec&& other) : ptr(other.ptr) { other.ptr = nullptr; }
  MjSpec& operator=(MjSpec&& other) {
    ptr = other.ptr;
    other.ptr = nullptr;
    return *this;
  }

  ~MjSpec() { mj_deleteSpec(ptr); }
  raw::MjSpec* ptr;
};

template <typename LoadFunc>
static raw::MjSpec* LoadSpecFileImpl(
    const std::string& filename,
    const std::vector<_impl::VfsAsset>& assets,
    LoadFunc&& loadfunc) {
  mjVFS vfs;
  mjVFS* vfs_ptr = nullptr;
  if (!assets.empty()) {
    mj_defaultVFS(&vfs);
    vfs_ptr = &vfs;
    for (const auto& asset : assets) {
      std::string buffer_name = _impl::StripPath(asset.name);
      const int vfs_error = InterceptMjErrors(mj_addBufferVFS)(
          vfs_ptr, buffer_name.c_str(), asset.content, asset.content_size);
      if (vfs_error) {
        mj_deleteVFS(vfs_ptr);
        if (vfs_error == 2) {
          throw py::value_error("Repeated file name in assets dict: " +
                                buffer_name);
        } else {
          throw py::value_error("Asset failed to load: " + buffer_name);
        }
      }
    }
  }

  raw::MjSpec* spec = loadfunc(filename.c_str(), vfs_ptr);
  mj_deleteVFS(vfs_ptr);
  return spec;
}

PYBIND11_MODULE(_specs, m) {
  auto structs_m = py::module::import("mujoco._structs");
  py::function mjmodel_from_spec_ptr =
      structs_m.attr("MjModel").attr("_from_spec_ptr");
  py::function mjmodel_mjdata_from_spec_ptr =
      structs_m.attr("_recompile_spec_addr");

  py::class_<MjSpec> mjSpec(m, "MjSpec");
  py::class_<raw::MjsElement> mjsElement(m, "MjsElement");
  py::class_<raw::MjsDefault> mjsDefault(m, "MjsDefault");
  py::class_<raw::MjsBody> mjsBody(m, "MjsBody");
  py::class_<raw::MjsFrame> mjsFrame(m, "MjsFrame");
  py::class_<raw::MjsGeom> mjsGeom(m, "MjsGeom");
  py::class_<raw::MjsJoint> mjsJoint(m, "MjsJoint");
  py::class_<raw::MjsLight> mjsLight(m, "MjsLight");
  py::class_<raw::MjsMaterial> mjsMaterial(m, "MjsMaterial");
  py::class_<raw::MjsSite> mjsSite(m, "MjsSite");
  py::class_<raw::MjsMesh> mjsMesh(m, "MjsMesh");
  py::class_<raw::MjsSkin> mjsSkin(m, "MjsSkin");
  py::class_<raw::MjsTexture> mjsTexture(m, "MjsTexture");
  py::class_<raw::MjsText> mjsText(m, "MjsText");
  py::class_<raw::MjsTuple> mjsTuple(m, "MjsTuple");
  py::class_<raw::MjsCamera> mjsCamera(m, "MjsCamera");
  py::class_<raw::MjsFlex> mjsFlex(m, "MjsFlex");
  py::class_<raw::MjsHField> mjsHField(m, "MjsHField");
  py::class_<raw::MjsKey> mjsKey(m, "MjsKey");
  py::class_<raw::MjsNumeric> mjsNumeric(m, "MjsNumeric");
  py::class_<raw::MjsPair> mjsPair(m, "MjsPair");
  py::class_<raw::MjsExclude> mjsExclude(m, "MjsExclude");
  py::class_<raw::MjsEquality> mjsEquality(m, "MjsEquality");
  py::class_<raw::MjsTendon> mjsTendon(m, "MjsTendon");
  py::class_<raw::MjsSensor> mjsSensor(m, "MjsSensor");
  py::class_<raw::MjsActuator> mjsActuator(m, "MjsActuator");
  py::class_<raw::MjsPlugin> mjsPlugin(m, "MjsPlugin");
  py::class_<raw::MjsOrientation> mjsOrientation(m, "MjsOrientation");
  py::class_<raw::MjsWrap> mjsWrap(m, "MjsWrap");
  py::class_<raw::MjOption> mjOption(m, "MjOption");
  py::class_<raw::MjStatistic> mjStatistic(m, "MjStatistic");
  py::class_<raw::MjVisual> mjVisual(m, "MjVisual");

  // ============================= MJSPEC =====================================
  mjSpec.def(py::init<>());
  mjSpec.def_static(
      "from_file",
      [](std::string& filename,
         std::optional<std::unordered_map<std::string, py::bytes>>& assets)
          -> MjSpec {
        const auto converted_assets = _impl::ConvertAssetsDict(assets);
        raw::MjSpec* spec;
        {
          py::gil_scoped_release no_gil;
          char error[1024];
          spec = LoadSpecFileImpl(
              filename, converted_assets,
              [&error](const char* filename, const mjVFS* vfs) {
                return InterceptMjErrors(mj_parseXML)(
                    filename, vfs, error, sizeof(error));
              });
          if (!spec) {
            throw py::value_error(error);
          }
        }
        return MjSpec(spec);
      },
      py::arg("filename"), py::arg("assets") = py::none(), R"mydelimiter(
    Creates a spec from an XML file.

    Parameters
    ----------
    filename : str
        Path to the XML file.
    assets : dict, optional
        A dictionary of assets to be used by the spec. The keys are asset names
        and the values are asset contents.
  )mydelimiter", py::return_value_policy::move);
  mjSpec.def_static(
      "from_string",
      [](std::string& xml,
         std::optional<std::unordered_map<std::string, py::bytes>>& assets)
          -> MjSpec {
        auto converted_assets = _impl::ConvertAssetsDict(assets);
        raw::MjSpec* spec;
        {
          py::gil_scoped_release no_gil;
          std::string model_filename = "model_.xml";
          if (assets.has_value()) {
            while (assets->find(model_filename) != assets->end()) {
              model_filename =
                  model_filename.substr(0, model_filename.size() - 4) + "_.xml";
            }
          }
          converted_assets.emplace_back(
              model_filename.c_str(), xml.c_str(), xml.length());
          char error[1024];
          spec = LoadSpecFileImpl(
              model_filename, converted_assets,
              [&error](const char* filename, const mjVFS* vfs) {
                return InterceptMjErrors(mj_parseXML)(
                    filename, vfs, error, sizeof(error));
              });
          if (!spec) {
            throw py::value_error(error);
          }
        }
        return MjSpec(spec);
      },
      py::arg("xml"), py::arg("assets") = py::none(), R"mydelimiter(
    Creates a spec from an XML string.

    Parameters
    ----------
    xml : str
        XML string.
    assets : dict, optional
        A dictionary of assets to be used by the spec. The keys are asset names
        and the values are asset contents.
  )mydelimiter", py::return_value_policy::move);
  mjSpec.def("recompile", [mjmodel_mjdata_from_spec_ptr](
                              const MjSpec& self, py::object m, py::object d) {
    return mjmodel_mjdata_from_spec_ptr(reinterpret_cast<uintptr_t>(self.ptr),
                                        m, d);
  });
  mjSpec.def(
      "copy",
      [](const MjSpec& self) -> raw::MjSpec* { return mj_copySpec(self.ptr); },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "worldbody",
      [](MjSpec& self) -> raw::MjsBody* {
        return mjs_findBody(self.ptr, "world");
      },
      py::return_value_policy::reference_internal);
  mjSpec.def(
      "find_body",
      [](MjSpec& self, std::string& name) -> raw::MjsBody* {
        return mjs_findBody(self.ptr, name.c_str());
      },
      py::return_value_policy::reference_internal);
  mjSpec.def(
      "find_frame",
      [](MjSpec& self, std::string& name) -> raw::MjsFrame* {
        return mjs_findFrame(self.ptr, name.c_str());
      },
      py::return_value_policy::reference_internal);
  mjSpec.def(
      "find_default",
      [](MjSpec& self, std::string& classname) -> raw::MjsDefault* {
        return mjs_findDefault(self.ptr, classname.c_str());
      },
      py::return_value_policy::reference_internal);
  mjSpec.def("compile", [mjmodel_from_spec_ptr](MjSpec& self) {
    return mjmodel_from_spec_ptr(reinterpret_cast<uintptr_t>(self.ptr));
  });
  mjSpec.def(
      "compile",
      [mjmodel_from_spec_ptr](MjSpec& self, py::dict& assets) -> py::object {
        mjVFS vfs;
        mj_defaultVFS(&vfs);
        for (auto item : assets) {
          std::string buffer = py::cast<std::string>(item.second);
          mj_addBufferVFS(&vfs, py::cast<std::string>(item.first).c_str(),
                          buffer.c_str(), buffer.size());
        };
        auto model =
            mjmodel_from_spec_ptr(reinterpret_cast<uintptr_t>(self.ptr),
                                  reinterpret_cast<uintptr_t>(&vfs));
        mj_deleteVFS(&vfs);
        return model;
      }, R"mydelimiter(
    Compiles the spec and returns the compiled model.

    Parameters
    ----------
    assets : dict, optional
        A dictionary of assets to be used by the spec. The keys are asset names
        and the values are asset contents.
  )mydelimiter");
  mjSpec.def(
      "copy_back",
      [](MjSpec& self, raw::MjModel& model) {
        return mj_copyBack(self.ptr, &model);
      },
      py::return_value_policy::reference_internal);
  mjSpec.def("to_xml", [](MjSpec& self) -> std::string {
    int size = mj_saveXMLString(self.ptr, nullptr, 0, nullptr, 0);
    std::unique_ptr<char[]> buf(new char[size + 1]);
    std::array<char, 1024> err;
    buf[0] = '\0';
    err[0] = '\0';
    mj_saveXMLString(self.ptr, buf.get(), size + 1, err.data(), err.size());
    if (err[0] != '\0') {
      throw FatalError(std::string(err.data()));
    }
    return std::string(buf.get());
  });
  mjSpec.def(
      "add_default",
      [](MjSpec* spec, std::string& classname,
         raw::MjsDefault* parent) -> raw::MjsDefault* {
        return mjs_addDefault(spec->ptr, classname.c_str(), parent);
      },
      py::return_value_policy::reference_internal);
  mjSpec.def(
      "default",
      [](MjSpec& self) -> raw::MjsDefault* {
        return mjs_getSpecDefault(self.ptr);
      },
      py::return_value_policy::reference_internal);
  mjSpec.def("detach_body", [](MjSpec& self, raw::MjsBody& body) {
    mjs_detachBody(self.ptr, &body);
  });
    mjSpec.def_property_readonly(
      "plugins",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_PLUGIN);
        while (el) {
          list.append(mjs_asPlugin(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "actuators",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_ACTUATOR);
        while (el) {
          list.append(mjs_asActuator(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "sensors",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SENSOR);
        while (el) {
          list.append(mjs_asSensor(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "flexes",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_FLEX);
        while (el) {
          list.append(mjs_asFlex(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "pairs",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_PAIR);
        while (el) {
          list.append(mjs_asPair(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "equality",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EQUALITY);
        while (el) {
          list.append(mjs_asEquality(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "excludes",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_EXCLUDE);
        while (el) {
          list.append(mjs_asExclude(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "tendons",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TENDON);
        while (el) {
          list.append(mjs_asTendon(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "numeric",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_NUMERIC);
        while (el) {
          list.append(mjs_asNumeric(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "text",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXT);
        while (el) {
          list.append(mjs_asText(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "tuple",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TUPLE);
        while (el) {
          list.append(mjs_asTuple(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "key",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_KEY);
        while (el) {
          list.append(mjs_asKey(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "mesh",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MESH);
        while (el) {
          list.append(mjs_asMesh(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "hfield",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_HFIELD);
        while (el) {
          list.append(mjs_asHField(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "skin",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_SKIN);
        while (el) {
          list.append(mjs_asSkin(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "texture",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_TEXTURE);
        while (el) {
          list.append(mjs_asTexture(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);
  mjSpec.def_property_readonly(
      "material",
      [](MjSpec& self) -> py::list {
        py::list list;
        raw::MjsElement* el = mjs_firstElement(self.ptr, mjOBJ_MATERIAL);
        while (el) {
          list.append(mjs_asMaterial(el));
          el = mjs_nextElement(self.ptr, el);
        }
        return list;
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSBODY =====================================
  mjsBody.def_property_readonly(
      "id", [](raw::MjsBody& self) -> int { return mjs_getId(self.element); });
  mjsBody.def(
      "add_freejoint",
      [](raw::MjsBody& self, py::kwargs kwargs) -> raw::MjsJoint* {
        auto out = mjs_addFreeJoint(&self);
        py::dict kwarg_dict = kwargs;
        for (auto item : kwarg_dict) {
          std::string key = py::str(item.first);
          if (key == "align") {
            try {
              out->align = kwargs["align"].cast<int>();
            } catch (const py::cast_error& e) {
              throw pybind11::value_error("align is the wrong type.");
            }
          } else if (key == "name") {
            try {
              *out->name = kwargs["name"].cast<std::string>();
            } catch (const py::cast_error& e) {
              throw pybind11::value_error("name is the wrong type.");
            }
          } else if (key == "group") {
            try {
              out->group = kwargs["group"].cast<int>();
            } catch (const py::cast_error& e) {
              throw pybind11::value_error("group is the wrong type.");
            }
          } else {
            throw pybind11::type_error(
                "Invalid " + key +
                " keyword argument. Valid options are: align, group, name.");
          }
        }
        return out;
      },
      py::return_value_policy::reference_internal);
  mjsBody.def("set_frame",
              [](raw::MjsBody& self, raw::MjsFrame& frame) -> void {
                mjs_setFrame(self.element, &frame);
              });
  mjsBody.def("set_default",
              [](raw::MjsBody& self, raw::MjsDefault& default_) -> void {
                mjs_setDefault(self.element, &default_);
              });
  mjsBody.def(
      "default",
      [](raw::MjsBody& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "find_child",
      [](raw::MjsBody& self, std::string& name) -> raw::MjsBody* {
        return mjs_findChild(&self, name.c_str());
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_body",
      [](raw::MjsBody& self) -> raw::MjsBody* {
        return mjs_asBody(mjs_firstChild(&self, mjOBJ_BODY));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_body",
      [](raw::MjsBody& self, raw::MjsBody& child) -> raw::MjsBody* {
        return mjs_asBody(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_camera",
      [](raw::MjsBody& self) -> raw::MjsCamera* {
        return mjs_asCamera(mjs_firstChild(&self, mjOBJ_CAMERA));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_camera",
      [](raw::MjsBody& self, raw::MjsCamera& child) -> raw::MjsCamera* {
        return mjs_asCamera(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_light",
      [](raw::MjsBody& self) -> raw::MjsLight* {
        return mjs_asLight(mjs_firstChild(&self, mjOBJ_LIGHT));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_light",
      [](raw::MjsBody& self, raw::MjsLight& child) -> raw::MjsLight* {
        return mjs_asLight(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_joint",
      [](raw::MjsBody& self) -> raw::MjsJoint* {
        return mjs_asJoint(mjs_firstChild(&self, mjOBJ_JOINT));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_joint",
      [](raw::MjsBody& self, raw::MjsJoint& child) -> raw::MjsJoint* {
        return mjs_asJoint(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_geom",
      [](raw::MjsBody& self) -> raw::MjsGeom* {
        return mjs_asGeom(mjs_firstChild(&self, mjOBJ_GEOM));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_geom",
      [](raw::MjsBody& self, raw::MjsGeom& child) -> raw::MjsGeom* {
        return mjs_asGeom(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_site",
      [](raw::MjsBody& self) -> raw::MjsSite* {
        return mjs_asSite(mjs_firstChild(&self, mjOBJ_SITE));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_site",
      [](raw::MjsBody& self, raw::MjsSite& child) -> raw::MjsSite* {
        return mjs_asSite(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "first_frame",
      [](raw::MjsBody& self) -> raw::MjsFrame* {
        return mjs_asFrame(mjs_firstChild(&self, mjOBJ_FRAME));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "next_frame",
      [](raw::MjsBody& self, raw::MjsFrame& child) -> raw::MjsFrame* {
        return mjs_asFrame(mjs_nextChild(&self, child.element));
      },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "spec",
      [](raw::MjsBody& self) -> raw::MjSpec* { return mjs_getSpec(&self); },
      py::return_value_policy::reference_internal);
  mjsBody.def(
      "attach_frame",
      [](raw::MjsBody& self, raw::MjsFrame& frame, std::string& prefix,
         std::string& suffix) -> raw::MjsFrame* {
        return mjs_attachFrame(&self, &frame, prefix.c_str(), suffix.c_str());
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSFRAME ====================================
  mjsFrame.def_property_readonly(
      "id", [](raw::MjsFrame& self) -> int { return mjs_getId(self.element); });
  mjsFrame.def("delete", [](raw::MjsFrame& self) { mjs_delete(self.element); });
  mjsFrame.def("set_frame", [](raw::MjsFrame& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsFrame.def(
      "attach_body",
      [](raw::MjsFrame& self, raw::MjsBody& body, std::string& prefix,
         std::string& suffix) -> raw::MjsBody* {
        return mjs_attachBody(&self, &body, prefix.c_str(), suffix.c_str());
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSGEOM =====================================
  mjsGeom.def_property_readonly(
      "id", [](raw::MjsGeom& self) -> int { return mjs_getId(self.element); });
  mjsGeom.def("delete", [](raw::MjsGeom& self) { mjs_delete(self.element); });
  mjsGeom.def("set_frame", [](raw::MjsGeom& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsGeom.def("set_default", [](raw::MjsGeom& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsGeom.def(
      "default",
      [](raw::MjsGeom& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSJOINT ====================================
  mjsJoint.def_property_readonly(
      "id", [](raw::MjsJoint& self) -> int { return mjs_getId(self.element); });
  mjsJoint.def("delete", [](raw::MjsJoint& self) { mjs_delete(self.element); });
  mjsJoint.def("set_frame", [](raw::MjsJoint& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsJoint.def("set_default", [](raw::MjsJoint& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsJoint.def(
      "default",
      [](raw::MjsJoint& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSSITE =====================================
  mjsSite.def_property_readonly(
      "id", [](raw::MjsSite& self) -> int { return mjs_getId(self.element); });
  mjsSite.def("delete", [](raw::MjsSite& self) { mjs_delete(self.element); });
  mjsSite.def("set_frame", [](raw::MjsSite& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsSite.def("set_default", [](raw::MjsSite& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsSite.def(
      "default",
      [](raw::MjsSite& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSCAMERA ===================================
  mjsCamera.def_property_readonly("id", [](raw::MjsCamera& self) -> int {
    return mjs_getId(self.element);
  });
  mjsCamera.def("delete",
                [](raw::MjsCamera& self) { mjs_delete(self.element); });
  mjsCamera.def("set_frame", [](raw::MjsCamera& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsCamera.def("set_default", [](raw::MjsCamera& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsCamera.def(
      "default",
      [](raw::MjsCamera& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSLIGHT ====================================
  mjsLight.def_property_readonly(
      "id", [](raw::MjsLight& self) -> int { return mjs_getId(self.element); });
  mjsLight.def("delete", [](raw::MjsLight& self) { mjs_delete(self.element); });
  mjsLight.def("set_frame", [](raw::MjsLight& self, raw::MjsFrame& frame) {
    mjs_setFrame(self.element, &frame);
  });
  mjsLight.def("set_default", [](raw::MjsLight& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsLight.def(
      "default",
      [](raw::MjsLight& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSMATERIAL =================================
  mjsMaterial.def_property_readonly("id", [](raw::MjsMaterial& self) -> int {
    return mjs_getId(self.element);
  });
  mjsMaterial.def("delete",
                  [](raw::MjsMaterial& self) { mjs_delete(self.element); });
  mjsMaterial.def("set_default",
                  [](raw::MjsMaterial& self, raw::MjsDefault& def) {
                    mjs_setDefault(self.element, &def);
                  });
  mjsMaterial.def(
      "default",
      [](raw::MjsMaterial& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSMESH =====================================
  mjsMesh.def_property_readonly(
      "id", [](raw::MjsMesh& self) -> int { return mjs_getId(self.element); });
  mjsMesh.def("delete", [](raw::MjsMesh& self) { mjs_delete(self.element); });
  mjsMesh.def("set_default", [](raw::MjsMesh& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsMesh.def(
      "default",
      [](raw::MjsMesh& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSPAIR =====================================
  mjsPair.def_property_readonly(
      "id", [](raw::MjsPair& self) -> int { return mjs_getId(self.element); });
  mjsPair.def("delete", [](raw::MjsPair& self) { mjs_delete(self.element); });
  mjsPair.def("set_default", [](raw::MjsPair& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsPair.def(
      "default",
      [](raw::MjsPair& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSEQUAL ====================================
  mjsEquality.def_property_readonly("id", [](raw::MjsEquality& self) -> int {
    return mjs_getId(self.element);
  });
  mjsEquality.def("delete",
                  [](raw::MjsEquality& self) { mjs_delete(self.element); });
  mjsEquality.def("set_default",
                  [](raw::MjsEquality& self, raw::MjsDefault& def) {
                    mjs_setDefault(self.element, &def);
                  });
  mjsEquality.def(
      "default",
      [](raw::MjsEquality& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSACTUATOR =================================
  mjsActuator.def_property_readonly("id", [](raw::MjsActuator& self) -> int {
    return mjs_getId(self.element);
  });
  mjsActuator.def("delete",
                  [](raw::MjsActuator& self) { mjs_delete(self.element); });
  mjsActuator.def("set_default",
                  [](raw::MjsActuator& self, raw::MjsDefault& def) {
                    mjs_setDefault(self.element, &def);
                  });
  mjsActuator.def(
      "default",
      [](raw::MjsActuator& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSTENDON ===================================
  mjsTendon.def_property_readonly("id", [](raw::MjsTendon& self) -> int {
    return mjs_getId(self.element);
  });
  mjsTendon.def("delete",
                [](raw::MjsTendon& self) { mjs_delete(self.element); });
  mjsTendon.def("set_default", [](raw::MjsTendon& self, raw::MjsDefault& def) {
    mjs_setDefault(self.element, &def);
  });
  mjsTendon.def(
      "default",
      [](raw::MjsTendon& self) -> raw::MjsDefault* {
        return mjs_getDefault(self.element);
      },
      py::return_value_policy::reference_internal);
  mjsTendon.def(
      "wrap_site",
      [](raw::MjsTendon& self, std::string& name) {
        return mjs_wrapSite(&self, name.c_str());
      },
      py::return_value_policy::reference_internal);
  mjsTendon.def(
      "wrap_geom",
      [](raw::MjsTendon& self, std::string& name, std::string& sidesite) {
        return mjs_wrapGeom(&self, name.c_str(), sidesite.c_str());
      },
      py::return_value_policy::reference_internal);
  mjsTendon.def(
      "wrap_joint",
      [](raw::MjsTendon& self, std::string& name, double coef) {
        return mjs_wrapJoint(&self, name.c_str(), coef);
      },
      py::return_value_policy::reference_internal);
  mjsTendon.def(
      "wrap_pulley",
      [](raw::MjsTendon& self, double divisor) {
        return mjs_wrapPulley(&self, divisor);
      },
      py::return_value_policy::reference_internal);

  // ============================= MJSSENSOR ===================================
  mjsSensor.def_property_readonly("id", [](raw::MjsSensor& self) -> int {
    return mjs_getId(self.element);
  });
  mjsSensor.def("delete",
                [](raw::MjsSensor& self) { mjs_delete(self.element); });

  // ============================= MJSFLEX =====================================
  mjsFlex.def_property_readonly(
      "id", [](raw::MjsFlex& self) -> int { return mjs_getId(self.element); });
  mjsFlex.def("delete", [](raw::MjsFlex& self) { mjs_delete(self.element); });

  // ============================= MJSHFIELD ===================================
  mjsHField.def_property_readonly("id", [](raw::MjsHField& self) -> int {
    return mjs_getId(self.element);
  });
  mjsHField.def("delete",
                [](raw::MjsHField& self) { mjs_delete(self.element); });

  // ============================= MJSSKIN =====================================
  mjsSkin.def_property_readonly(
      "id", [](raw::MjsSkin& self) -> int { return mjs_getId(self.element); },
      py::return_value_policy::reference_internal);
  mjsSkin.def("delete", [](raw::MjsSkin& self) { mjs_delete(self.element); });

  // ============================= MJSTEXTURE ==================================
  mjsTexture.def_property_readonly("id", [](raw::MjsTexture& self) -> int {
    return mjs_getId(self.element);
  });
  mjsTexture.def("delete",
                 [](raw::MjsTexture& self) { mjs_delete(self.element); });

  // ============================= MJSKEY ======================================
  mjsKey.def_property_readonly(
      "id", [](raw::MjsKey& self) -> int { return mjs_getId(self.element); });
  mjsKey.def("delete", [](raw::MjsKey& self) { mjs_delete(self.element); });

  // ============================= MJSTEXT =====================================
  mjsText.def_property_readonly(
      "id", [](raw::MjsText& self) -> int { return mjs_getId(self.element); });
  mjsText.def("delete", [](raw::MjsText& self) { mjs_delete(self.element); });

  // ============================= MJSNUMERIC ==================================
  mjsNumeric.def_property_readonly("id", [](raw::MjsNumeric& self) -> int {
    return mjs_getId(self.element);
  });
  mjsNumeric.def("delete",
                 [](raw::MjsNumeric& self) { mjs_delete(self.element); });

  // ============================= MJSEXCLUDE ==================================
  mjsExclude.def_property_readonly("id", [](raw::MjsExclude& self) -> int {
    return mjs_getId(self.element);
  });
  mjsExclude.def("delete",
                 [](raw::MjsExclude& self) { mjs_delete(self.element); });

  // ============================= MJSTUPLE ====================================
  mjsTuple.def_property_readonly(
      "id", [](raw::MjsTuple& self) -> int { return mjs_getId(self.element); });
  mjsTuple.def("delete", [](raw::MjsTuple& self) { mjs_delete(self.element); });

  // ============================= MJSPLUGIN ===================================
  mjsPlugin.def_property(
      "id",
      [](raw::MjsPlugin& self) -> int { return mjs_getId(self.element); },
      [](raw::MjsPlugin& self, raw::MjsPlugin* other) {
        self.element = other->element;
      });
  mjsPlugin.def("delete",
                [](raw::MjsPlugin& self) { mjs_delete(self.element); });

#include "specs.cc.inc"
}  // PYBIND11_MODULE // NOLINT
}  // namespace mujoco::python