Attempt to use new plugin format for tree nodes.

Crude support for gazebo ignition

src/ign_actor_plugin/CMakeLists.txt

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.24)
+project(ActorPlugin)
+
+set(IGN_PLUGIN_VER 0)
+find_package(ignition-cmake2 REQUIRED)
+find_package(ignition-gazebo5 REQUIRED)
+ign_find_package(ignition-plugin1 REQUIRED COMPONENTS register)
+set(IGN_PLUGIN_VER ${ignition-plugin1_VERSION_MAJOR})
+# Add sources for each plugin to be registered.
+add_library(SampleSystem src/ActorSystem.cpp)
+set_property(TARGET SampleSystem PROPERTY CXX_STANDARD 17)
+target_link_libraries(SampleSystem
+        ignition-plugin${IGN_PLUGIN_VER}::ignition-plugin${IGN_PLUGIN_VER}
+        ignition-gazebo5::ignition-gazebo5
+        )

src/ign_actor_plugin/src/ActorSystem.cpp

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+//
+// Created by bastian on 31.08.22.
+//
+
+#include "ActorSystem.h"
+
+IGNITION_ADD_PLUGIN(
+        ActorSystem,
+        ignition::gazebo::System,
+        ActorSystem::ISystemPreUpdate)
+
+ActorSystem::ActorSystem() = default;
+
+ActorSystem::~ActorSystem() = default;
+
+void ActorSystem::PreUpdate(const ignition::gazebo::UpdateInfo &_info, ignition::gazebo::EntityComponentManager &_ecm) {
+
+}

src/ign_actor_plugin/src/ActorSystem.h

@@ -0,0 +1,26 @@
+//
+// Created by bastian on 31.08.22.
+//
+
+#ifndef BUILD_ACTORSYSTEM_H
+#define BUILD_ACTORSYSTEM_H
+
+#include <ignition/gazebo/System.hh>
+#include <ignition/plugin/Register.hh>
+
+class ActorSystem:
+        public ignition::gazebo::System,
+        public ignition::gazebo::ISystemPreUpdate {
+
+public:
+    ActorSystem();
+
+public:
+    ~ActorSystem() override;
+
+public: void PreUpdate(const ignition::gazebo::UpdateInfo &_info,
+            ignition::gazebo::EntityComponentManager &_ecm) override;
+};
+
+
+#endif //BUILD_ACTORSYSTEM_H