Example of using custom messages in the ros project

ros_gz_example_gazebo/CMakeLists.txt

@@ -14,9 +14,30 @@ find_package(gz-plugin2 REQUIRED COMPONENTS register)
 set(GZ_PLUGIN_VER ${gz-plugin2_VERSION_MAJOR})
 find_package(gz-common5 REQUIRED COMPONENTS profiler)
 set(GZ_COMMON_VER ${gz-common5_VERSION_MAJOR})
-find_package(gz-sim7 REQUIRED)
-set(GZ_SIM_VER ${gz-sim7_VERSION_MAJOR})
 
+find_package(gz-sim8 REQUIRED)
+set(GZ_SIM_VER ${gz-sim8_VERSION_MAJOR})
+
+find_package(gz-msgs10 REQUIRED)
+set(GZ_MSGS_VER ${gz-msgs10_VERSION_MAJOR})
+
+# Example of custom messages that depend on gz.msgs
+set(MSGS_PROTOS
+   ${CMAKE_CURRENT_SOURCE_DIR}/proto/ros_gz_example_gazebo/msgs/foobar.proto
+)
+
+gz_msgs_generate_messages(
+  # The cmake target to be generated for libraries/executables to link
+  TARGET msgs
+  # The protobuf package to generate (Typically based on the path)
+  PROTO_PACKAGE "ros_gz_example_gazebo.msgs"
+  # The path to the base directory of the proto files
+  # All import paths should be relative to this (eg gz/custom_msgs/vector3d.proto)
+  MSGS_PATH ${CMAKE_CURRENT_SOURCE_DIR}/proto
+  # List of proto files to generate
+  MSGS_PROTOS ${MSGS_PROTOS}
+  DEPENDENCIES gz-msgs${GZ_MSGS_VER}::gz-msgs${GZ_MSGS_VER}
+)
 
 # Following 'add_library' directive defines a library target named 'BasicSystem'.
 # The 'SHARED' keyword indicates that a shared library should be compiled, and
@@ -34,11 +55,11 @@ target_include_directories(
   BasicSystem PRIVATE include
 )
 
-# Following 'target_link_libraries' directive specifies to use the 
+# Following 'target_link_libraries' directive specifies to use the
 # gz-sim library when linking the 'BasicSystem' target.
 # The 'PRIVATE' keyword stipulates that the gz-sim library will not
 # automatically be included if the 'BasicSystem' target were to
-# be linked to anoter target. 
+# be linked to anoter target.
 # ${GZ_SIM_VER} is substituted by the value that is was set to above.
 target_link_libraries(BasicSystem PRIVATE
   gz-sim${GZ_SIM_VER}::gz-sim${GZ_SIM_VER})
@@ -55,7 +76,10 @@ target_include_directories(
 )
 
 target_link_libraries(FullSystem PRIVATE
-  gz-sim${GZ_SIM_VER}::gz-sim${GZ_SIM_VER})
+  gz-sim${GZ_SIM_VER}::gz-sim${GZ_SIM_VER}
+  ros_gz_example_gazebo-msgs
+)
+
 
 
 

ros_gz_example_gazebo/hooks/ros_gz_example_gazebo.dsv.in

@@ -1,2 +1,3 @@
 prepend-non-duplicate;GZ_SIM_RESOURCE_PATH;share/@PROJECT_NAME@/worlds
 prepend-non-duplicate;GZ_SIM_SYSTEM_PLUGIN_PATH;lib/@PROJECT_NAME@/
+prepend-non-duplicate;GZ_DESCRIPTOR_PATH;share/gz/protos/

ros_gz_example_gazebo/hooks/ros_gz_example_gazebo.sh.in

@@ -1,2 +1,3 @@
 ament_prepend_unique_value GZ_SIM_RESOURCE_PATH "$AMENT_CURRENT_PREFIX/share/@PROJECT_NAME@/worlds"
 ament_prepend_unique_value GZ_SIM_PLUGIn_PATH "$AMENT_CURRENT_PREFIX/lib/@PROJECT_NAME@"
+ament_prepend_unique_value GZ_DESCRIPTOR_PATH "$AMENT_CURRENT_PREFIX/share/gz/protos/"

ros_gz_example_gazebo/include/ros_gz_example_gazebo/FullSystem.hh

@@ -23,6 +23,8 @@
 #include <gz/sim/EventManager.hh>
 #include <gz/sim/System.hh>
 
+#include <gz/utils/ImplPtr.hh>
+
 namespace ros_gz_example_gazebo
 {
   // This is the main plugin's class. It must inherit from System and at least
@@ -38,8 +40,11 @@ namespace ros_gz_example_gazebo
     public gz::sim::ISystemPostUpdate,
     public gz::sim::ISystemReset
   {
-    // Plugins inheriting ISystemConfigure must implement the Configure 
-    // callback. This is called when a system is initially loaded. 
+    // Construtor
+    public: FullSystem();
+
+    // Plugins inheriting ISystemConfigure must implement the Configure
+    // callback. This is called when a system is initially loaded.
     // The _entity variable contains the entity that the system is attached to
     // The _element variable contains the sdf Element with custom configuration
     // The _ecm provides an interface to all entities and components
@@ -74,10 +79,12 @@ namespace ros_gz_example_gazebo
     public: void PostUpdate(const gz::sim::UpdateInfo &_info,
                 const gz::sim::EntityComponentManager &_ecm) override;
 
-    // Plugins inheriting ISystemReset must implement the Reset callback. 
+    // Plugins inheriting ISystemReset must implement the Reset callback.
     // This is called when simulation is reset/rewound to initial conditions.
     public: void Reset(const gz::sim::UpdateInfo &_info,
                 gz::sim::EntityComponentManager &_ecm) override;
+
+    GZ_UTILS_UNIQUE_IMPL_PTR(dataPtr)
   };
 }
 #endif

ros_gz_example_gazebo/proto/ros_gz_example_gazebo/msgs/foobar.proto

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2023 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.
+ *
+*/
+
+syntax = "proto3";
+
+package ros_gz_example_gazebo.msgs;
+
+import "gz/msgs/header.proto";
+
+message Foobar
+{
+  double value = 1;
+}
+
+message FoobarStamped
+{
+  gz.msgs.Header header = 1;
+  Foobar foobar = 2;
+}

ros_gz_example_gazebo/src/FullSystem.cc

@@ -24,6 +24,10 @@
 // in the cc file, like it's done here.
 #include <gz/plugin/Register.hh>
 
+#include <ros_gz_example_gazebo/msgs/foobar.pb.h>
+
+#include <gz/transport/Node.hh>
+
 // Don't forget to include the plugin's header.
 #include "ros_gz_example_gazebo/FullSystem.hh"
 
@@ -39,9 +43,23 @@ GZ_ADD_PLUGIN(
     ros_gz_example_gazebo::FullSystem::ISystemReset
 )
 
-namespace ros_gz_example_gazebo 
+namespace ros_gz_example_gazebo
 {
 
+class FullSystem::Implementation
+{
+  public: gz::transport::Node node;
+
+  public: gz::transport::Node::Publisher pub;
+};
+
+FullSystem::FullSystem()
+: dataPtr(gz::utils::MakeUniqueImpl<Implementation>())
+{
+  this->dataPtr->pub =
+    this->dataPtr->node.Advertise<ros_gz_example_gazebo::msgs::FoobarStamped>("foobar");
+}
+
 void FullSystem::Configure(const gz::sim::Entity &_entity,
                 const std::shared_ptr<const sdf::Element> &_element,
                 gz::sim::EntityComponentManager &_ecm,
@@ -56,6 +74,14 @@ void FullSystem::PreUpdate(const gz::sim::UpdateInfo &_info,
   if (!_info.paused && _info.iterations % 1000 == 0)
   {
     gzdbg << "ros_gz_example_gazebo::FullSystem::PreUpdate" << std::endl;
+
+    ros_gz_example_gazebo::msgs::FoobarStamped msg;
+    auto *header = msg.mutable_header();
+    auto simTime = gz::math::durationToSecNsec(_info.simTime);
+    header->mutable_stamp()->set_sec(simTime.first);
+    header->mutable_stamp()->set_nsec(simTime.second);
+    msg.mutable_foobar()->set_value(_info.iterations % 1000);
+    this->dataPtr->pub.Publish(msg);
   }
 }
 
@@ -69,7 +95,7 @@ void FullSystem::Update(const gz::sim::UpdateInfo &_info,
 }
 
 void FullSystem::PostUpdate(const gz::sim::UpdateInfo &_info,
-                            const gz::sim::EntityComponentManager &_ecm) 
+                            const gz::sim::EntityComponentManager &_ecm)
 {
   if (!_info.paused && _info.iterations % 1000 == 0)
   {