Added Python interfaces to some Ignition Gazebo methods (#1219)

Signed-off-by: ahcorde <[email protected]>
Co-authored-by: Louise Poubel <[email protected]>
Co-authored-by: Jose Luis Rivero <[email protected]>

.github/ci/packages-focal.apt

@@ -3,3 +3,4 @@ libdart-dev
 libdart-external-ikfast-dev
 libdart-external-odelcpsolver-dev
 libdart-utils-urdf-dev
+python3-ignition-math6

.github/ci/packages.apt

@@ -22,6 +22,8 @@ libsdformat12-dev
 libtinyxml2-dev
 libxi-dev
 libxmu-dev
+python3-distutils
+python3-pybind11
 qml-module-qt-labs-folderlistmodel
 qml-module-qt-labs-settings
 qml-module-qtqml-models2

CMakeLists.txt

@@ -15,6 +15,7 @@ find_package(ignition-cmake2 2.8.0 REQUIRED)
 # Configure the project
 #============================================================================
 ign_configure_project(VERSION_SUFFIX)
+set (CMAKE_CXX_STANDARD 17)
 
 #============================================================================
 # Set project-specific options
@@ -37,6 +38,14 @@ endif()
 include(test/find_dri.cmake)
 FindDRI()
 
+option(USE_SYSTEM_PATHS_FOR_PYTHON_INSTALLATION
+      "Install python modules in standard system paths in the system"
+      OFF)
+
+option(USE_DIST_PACKAGES_FOR_PYTHON
+      "Use dist-packages instead of site-package to install python modules"
+      OFF)
+
 #============================================================================
 # Search for project-specific dependencies
 #============================================================================
@@ -167,6 +176,26 @@ ign_find_package(IgnProtobuf
                  PRETTY Protobuf)
 set(Protobuf_IMPORT_DIRS ${ignition-msgs8_INCLUDE_DIRS})
 
+#--------------------------------------
+# Find python
+include(IgnPython)
+find_package(PythonLibs QUIET)
+if (NOT PYTHONLIBS_FOUND)
+  IGN_BUILD_WARNING("Python is missing: Python interfaces are disabled.")
+  message (STATUS "Searching for Python - not found.")
+else()
+  message (STATUS "Searching for Python - found version ${PYTHONLIBS_VERSION_STRING}.")
+
+  set(PYBIND11_PYTHON_VERSION 3)
+  find_package(pybind11 2.2 QUIET)
+
+  if (${pybind11_FOUND})
+    message (STATUS "Searching for pybind11 - found version ${pybind11_VERSION}.")
+	else()
+		IGN_BUILD_WARNING("pybind11 is missing: Python interfaces are disabled.")
+		message (STATUS "Searching for pybind11 - not found.")
+	endif()
+endif()
 # Plugin install dirs
 set(IGNITION_GAZEBO_PLUGIN_INSTALL_DIR
   ${CMAKE_INSTALL_PREFIX}/${IGN_LIB_INSTALL_DIR}/ign-${IGN_DESIGNATION}-${PROJECT_VERSION_MAJOR}/plugins
@@ -187,6 +216,9 @@ add_subdirectory(examples)
 #============================================================================
 ign_create_packages()
 
+if (${pybind11_FOUND})
+	add_subdirectory(python)
+endif()
 #============================================================================
 # Configure documentation
 #============================================================================

examples/scripts/python_api/README.md

@@ -0,0 +1,6 @@
+# Gazebo Python API
+
+This example shows how to use Gazebo's Python API.
+
+For more information, see the
+[Python interfaces](https://ignitionrobotics.org/api/gazebo/6.4/python_interfaces.html) tutorial.

examples/scripts/python_api/gravity.sdf

@@ -0,0 +1,22 @@
+<?xml version="1.0" ?>
+<sdf version="1.6">
+  <world name="gravity">
+    <plugin
+      filename="ignition-gazebo-physics-system"
+      name="ignition::gazebo::systems::Physics">
+    </plugin>
+
+    <model name="falling">
+      <link name="link">
+        <inertial>
+          <inertia>
+            <ixx>0.4</ixx>
+            <iyy>0.4</iyy>
+            <izz>0.4</izz>
+          </inertia>
+          <mass>1.0</mass>
+        </inertial>
+      </link>
+    </model>
+  </world>
+</sdf>

examples/scripts/python_api/testFixture.py

@@ -0,0 +1,85 @@
+#!/usr/bin/python3
+# Copyright (C) 2021 Open Source Robotics Foundation
+#
+# 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.
+
+# If you compiled Ignition Gazebo from source you should modify your
+# `PYTHONPATH`:
+#
+# export PYTHONPATH=$PYTHONPATH:<path to ws>/install/lib/python
+#
+# Now you can run the example:
+#
+# python3 examples/scripts/python_api/helperFixture.py
+
+import os
+import time
+
+from ignition.common import set_verbosity
+from ignition.gazebo import TestFixture, World, world_entity
+from ignition.math import Vector3d
+from sdformat import Element
+
+set_verbosity(4)
+
+file_path = os.path.dirname(os.path.realpath(__file__))
+
+helper = TestFixture(os.path.join(file_path, 'gravity.sdf'))
+
+post_iterations = 0
+iterations = 0
+pre_iterations = 0
+first_iteration = True
+
+
+def on_pre_udpate_cb(_info, _ecm):
+    global pre_iterations
+    global first_iteration
+    pre_iterations += 1
+    if first_iteration:
+        first_iteration = False
+        world_e = world_entity(_ecm);
+        print('World entity is ', world_e)
+        w = World(world_e)
+        v = w.gravity(_ecm)
+        print('Gravity ', v)
+        modelEntity = w.model_by_name(_ecm, 'falling')
+        print('Entity for falling model is: ', modelEntity)
+
+
+def on_udpate_cb(_info, _ecm):
+    global iterations
+    iterations += 1
+
+
+def on_post_udpate_cb(_info, _ecm):
+    global post_iterations
+    post_iterations += 1
+    if _info.sim_time.seconds == 1:
+        print('Post update sim time: ', _info.sim_time)
+
+
+helper.on_post_update(on_post_udpate_cb)
+helper.on_update(on_udpate_cb)
+helper.on_pre_update(on_pre_udpate_cb)
+helper.finalize()
+
+server = helper.server()
+server.run(False, 1000, False)
+
+while(server.is_running()):
+    time.sleep(0.1)
+
+print('iterations ', iterations)
+print('post_iterations ', post_iterations)
+print('pre_iterations ', pre_iterations)

python/CMakeLists.txt

@@ -0,0 +1,99 @@
+if(WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug")
+  # pybind11 logic for setting up a debug build when both a debug and release
+  # python interpreter are present in the system seems to be pretty much broken.
+  # This works around the issue.
+  set(PYTHON_LIBRARIES "${PYTHON_DEBUG_LIBRARIES}")
+endif()
+
+
+if(USE_SYSTEM_PATHS_FOR_PYTHON_INSTALLATION)
+  if(${CMAKE_VERSION} VERSION_LESS "3.12.0")
+    execute_process(
+      COMMAND "${PYTHON_EXECUTABLE}" -c "if True:
+  from distutils import sysconfig as sc
+  print(sc.get_python_lib(plat_specific=True))"
+      OUTPUT_VARIABLE Python3_SITEARCH
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+  else()
+    # Get install variable from Python3 module
+    # Python3_SITEARCH is available from 3.12 on, workaround if needed:
+    find_package(Python3 COMPONENTS Interpreter)
+  endif()
+
+  if(USE_DIST_PACKAGES_FOR_PYTHON)
+    string(REPLACE "site-packages" "dist-packages" IGN_PYTHON_INSTALL_PATH ${Python3_SITEARCH})
+  endif()
+else()
+  # If not a system installation, respect local paths
+  set(IGN_PYTHON_INSTALL_PATH ${IGN_LIB_INSTALL_DIR}/python)
+endif()
+
+# Set the build location and install location for a CPython extension
+function(configure_build_install_location _library_name)
+  # Install library for actual use
+  install(TARGETS ${_library_name}
+    DESTINATION "${IGN_PYTHON_INSTALL_PATH}/ignition"
+  )
+endfunction()
+
+pybind11_add_module(gazebo SHARED
+  src/ignition/gazebo/_ignition_gazebo_pybind11.cc
+  src/ignition/gazebo/EntityComponentManager.cc
+  src/ignition/gazebo/EventManager.cc
+  src/ignition/gazebo/TestFixture.cc
+  src/ignition/gazebo/Server.cc
+  src/ignition/gazebo/ServerConfig.cc
+  src/ignition/gazebo/UpdateInfo.cc
+  src/ignition/gazebo/Util.cc
+  src/ignition/gazebo/World.cc
+)
+
+target_link_libraries(gazebo PRIVATE
+  ${PROJECT_LIBRARY_TARGET_NAME}
+  sdformat${SDF_VER}::sdformat${SDF_VER}
+  ignition-common${IGN_COMMON_VER}::ignition-common${IGN_COMMON_VER}
+)
+
+# TODO(ahcorde): Move this module to ign-common
+pybind11_add_module(common SHARED
+  src/ignition/common/_ignition_common_pybind11.cc
+  src/ignition/common/Console.cc
+)
+
+target_link_libraries(common PRIVATE
+  ignition-common${IGN_COMMON_VER}::ignition-common${IGN_COMMON_VER}
+)
+
+# TODO(ahcorde): Move this module to sdformat
+pybind11_add_module(sdformat SHARED
+  src/ignition/sdformat/_sdformat_pybind11.cc
+  src/ignition/sdformat/Element.cc
+)
+
+target_link_libraries(sdformat PRIVATE
+	sdformat${SDF_VER}::sdformat${SDF_VER}
+)
+
+install(TARGETS sdformat
+	DESTINATION "${IGN_PYTHON_INSTALL_PATH}"
+)
+
+configure_build_install_location(gazebo)
+configure_build_install_location(common)
+
+if (BUILD_TESTING)
+  set(python_tests
+    testFixture_TEST
+  )
+
+  foreach (test ${python_tests})
+    add_test(NAME ${test}.py COMMAND
+      "${PYTHON_EXECUTABLE}" "${CMAKE_SOURCE_DIR}/python/test/${test}.py")
+
+    set(_env_vars)
+    list(APPEND _env_vars "PYTHONPATH=${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/python/")
+    list(APPEND _env_vars "LD_LIBRARY_PATH=${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}:$ENV{LD_LIBRARY_PATH}")
+    set_tests_properties(${test}.py PROPERTIES
+      ENVIRONMENT "${_env_vars}")
+  endforeach()
+endif()

python/src/ignition/common/Console.cc

@@ -0,0 +1,31 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// 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 <ignition/common/Console.hh>
+
+#include "Console.hh"
+
+namespace ignition
+{
+  namespace common
+  {
+    namespace python
+    {
+      void SetVerbosity(int _verbosity)
+      {
+        ignition::common::Console::SetVerbosity(_verbosity);
+      }
+    }
+  }
+}

python/src/ignition/common/Console.hh

@@ -0,0 +1,31 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// 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.
+
+#ifndef IGNITION_GAZEBO_PYTHON__CONSOLE_HH_
+#define IGNITION_GAZEBO_PYTHON__CONSOLE_HH_
+
+#include <pybind11/pybind11.h>
+
+namespace ignition
+{
+  namespace common
+  {
+    namespace python
+    {
+      void SetVerbosity(int _verbosity);
+    }
+  }
+}
+
+#endif

python/src/ignition/common/_ignition_common_pybind11.cc

@@ -0,0 +1,25 @@
+// Copyright 2021 Open Source Robotics Foundation, Inc.
+//
+// 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 <pybind11/pybind11.h>
+
+#include "Console.hh"
+
+PYBIND11_MODULE(common, m) {
+  m.doc() = "Ignition Common Python Library.";
+
+  m.def(
+    "set_verbosity", &ignition::common::python::SetVerbosity,
+    "Set verbosity level.");
+}