add a specific tutorial for plugins

examples/CMakeLists.txt

@@ -36,3 +36,15 @@ endif()
 CompileExample("ex01_wrap_legacy")
 CompileExample("ex02_runtime_ports")
 CompileExample("ex04_waypoints")
+
+CompileExample("t13_plugin_executor")
+
+############ Create plugin for tutorial 13 ##########
+# library must be SHARED
+add_library(t13_plugin_action SHARED t13_plugin_action.cpp )
+# you must set the definition BT_PLUGIN_EXPORT
+target_compile_definitions(t13_plugin_action PRIVATE  BT_PLUGIN_EXPORT )
+# remove the "lib" prefix. Name of the file will be t13_plugin_action.so
+set_target_properties(t13_plugin_action PROPERTIES PREFIX "")
+# link dependencies as usual
+target_link_libraries(t13_plugin_action ${BTCPP_LIBRARY} )

examples/t13_custom_type.hpp

@@ -0,0 +1,45 @@
+#pragma once
+
+#include "behaviortree_cpp/behavior_tree.h"
+#include "behaviortree_cpp/json_export.h"
+
+// my custom type
+struct Vector4D
+{
+  double w;
+  double x;
+  double y;
+  double z;
+};
+
+// add this just in case, if it is necessary to register it with
+// Groot2 publisher.
+// You will need to add `RegisterJsonDefinition<Vector4D>(ToJson);` in you main
+inline void ToJson(nlohmann::json& dest, const Vector4D& pose)
+{
+  dest["w"] = pose.w;
+  dest["x"] = pose.x;
+  dest["y"] = pose.y;
+  dest["z"] = pose.z;
+}
+
+namespace BT {
+
+template <> inline
+    Vector4D convertFromString(StringView key)
+{
+  const auto parts = BT::splitString(key, ',');
+  if (parts.size() != 4)
+  {
+    throw BT::RuntimeError("invalid input)");
+  }
+
+  Vector4D output;
+  output.w = convertFromString<double>(parts[0]);
+  output.x     = convertFromString<double>(parts[1]);
+  output.y     = convertFromString<double>(parts[2]);
+  output.z = convertFromString<double>(parts[3]);
+  return output;
+}
+
+}

examples/t13_plugin_action.cpp

@@ -0,0 +1,35 @@
+#include "t13_custom_type.hpp"
+#include "behaviortree_cpp/bt_factory.h"
+
+class ShowVector : public BT::SyncActionNode
+{
+public:
+  ShowVector(const std::string& name, const BT::NodeConfig& config)
+    : BT::SyncActionNode(name, config)
+  {
+  }
+
+  BT::NodeStatus tick() override
+  {
+    const auto v = getInput<Vector4D>("value").value();
+    printf("x:%f  y:%f  z:%f  w:%f\n", v.x, v.y, v.z, v.w);
+    return BT::NodeStatus::SUCCESS;
+  }
+
+  // It is mandatory to define this static method.
+  static BT::PortsList providedPorts()
+  {
+    return{ BT::InputPort<Vector4D>("value") };
+  }
+};
+
+// Function used to register ShowVector automatically, when
+// loading the plugin.
+// Remember that is mandatory to add to toy CMakeLists.txtx file
+// this:
+//    target_compile_definitions(<target_name> PRIVATE  BT_PLUGIN_EXPORT)
+//
+BT_REGISTER_NODES(factory)
+{
+  factory.registerNodeType<ShowVector>("ShowVector");
+}

examples/t13_plugin_executor.cpp

@@ -0,0 +1,37 @@
+#include "behaviortree_cpp/bt_factory.h"
+#include "t13_custom_type.hpp"
+
+static const char* xml_text = R"(
+
+// clang-format off
+ <root BTCPP_format="4" main_tree_to_execute="MainTree" >
+  <BehaviorTree ID="MainTree">
+    <Sequence>
+        <Script   code="vect:='1,2,3,4'"/>
+        <ShowVector value="{vect}"/>;
+        <SubTree ID="MySub" v4="{vect}"/>
+    </Sequence>
+  </BehaviorTree>
+
+  <BehaviorTree ID="MySub">
+    <ShowVector value="{v4}"/>;
+  </BehaviorTree>
+ </root>
+ )";
+// clang-format on
+
+int main(int argc, char** argv)
+{
+  using namespace BT;
+  BehaviorTreeFactory factory;
+  factory.registerFromPlugin("t13_plugin_action.so");
+
+  // Not mandatory, since we don't have a Groot2 publisher
+  RegisterJsonDefinition<Vector4D>(ToJson);
+
+  auto tree = factory.createTreeFromText(xml_text);
+  tree.tickWhileRunning();
+
+  return 0;
+}
+