objects example

Added simple demo that allows to spawn and move around objects at 
runtime.

Also, fixed format error in `unity_bridge.cpp`.

flightlib/src/bridges/unity_bridge.cpp

@@ -113,7 +113,8 @@ bool UnityBridge::getRender(const FrameID frame_id) {
     unity_quadrotors_[idx]->getState(&quad_state);
     pub_msg_.vehicles[idx].position = positionRos2Unity(quad_state.p);
     pub_msg_.vehicles[idx].rotation = quaternionRos2Unity(quad_state.q());
-    pub_msg_.vehicles[idx].size = scalarRos2Unity(unity_quadrotors_[idx]->getSize());
+    pub_msg_.vehicles[idx].size =
+      scalarRos2Unity(unity_quadrotors_[idx]->getSize());
   }
 
   // Update static objects as well

flightros/CMakeLists.txt

@@ -150,6 +150,20 @@ zmq
 zmqpp
 )
 
+# objects
+
+cs_add_executable(objects
+    src/objects/objects.cpp
+)
+
+target_link_libraries(objects
+${catkin_LIBRARIES}
+${OpenCV_LIBRARIES}
+stdc++fs
+zmq
+zmqpp
+)
+
 # Finish
 cs_install()
 cs_export()

flightros/launch/objects/objects.launch

@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<launch>
+    <arg name="debug" default="0" />
+    <arg name="use_unity_editor" default="false" />
+
+    <!-- RPG Flightmare Unity Render. -->
+    <node pkg="flightrender" type="RPG_Flightmare.x86_64" name="rpg_flightmare_render" unless="$(arg use_unity_editor)">
+    </node>
+
+    <node name="objects" pkg="flightros" type="objects" output="screen" launch-prefix="gdb -ex run --args" if="$(arg debug)" >
+    </node>
+
+    <node name="objects" pkg="flightros" type="objects" output="screen" unless="$(arg debug)">
+    </node>
+</launch>

flightros/src/objects/objects.cpp

@@ -0,0 +1,155 @@
+// ros
+#include <geometry_msgs/PoseStamped.h>
+#include <ros/ros.h>
+// flightlib
+#include "flightlib/bridges/unity_bridge.hpp"
+#include "flightlib/bridges/unity_message_types.hpp"
+#include "flightlib/common/types.hpp"
+#include "flightlib/objects/static_object.hpp"
+
+using namespace flightlib;
+
+// Split the string "[pre][sep][post]" into the pair ("[pre]","[post]").
+// Example: split("hello/world", "/") will result into ("hello","world").
+std::pair<std::string, std::string> split(const std::string& s,
+                                          const std::string& sep) {
+  auto idx = s.find(sep);
+  if (idx == std::string::npos)
+    return {s, ""};
+  else
+    return {s.substr(0, idx), s.substr(idx + 1)};
+}
+
+Vector<3> ros2flightmare(const geometry_msgs::Point& p) {
+  return Vector<3>(p.x, p.y, p.z);
+}
+
+Quaternion ros2flightmare(const geometry_msgs::Quaternion& q) {
+  return Quaternion(q.w, q.x, q.y, q.z);
+}
+
+
+// This class allows to add and move objects in Unity3D.
+class ObjectDatabase {
+ public:
+  // Connect to the pose topic.
+  ObjectDatabase(ros::NodeHandle& nh,
+                 std::shared_ptr<UnityBridge> unity_bridge_ptr) {
+    if (unity_bridge_ptr == nullptr) {
+      throw std::runtime_error("ObjectDatabase: unity_bridge_ptr is nullptr");
+    }
+    bridge_ = unity_bridge_ptr;
+    sub_ = nh.subscribe("update_object", 1, &ObjectDatabase::poseCB, this);
+  }
+
+  std::string getTopic() const { return sub_.getTopic(); }
+
+ private:
+  std::shared_ptr<UnityBridge> bridge_;
+  std::map<std::string, std::shared_ptr<StaticObject>> database_;
+  ros::Subscriber sub_;
+
+  // Update the database.
+  void poseCB(const geometry_msgs::PoseStamped& msg) {
+    // discard messages with empty frame_id
+    if (msg.header.frame_id.empty()) {
+      ROS_WARN("Received pose message with empty frame_id");
+      return;
+    }
+    // split the header, which should be in the form "name/type" or at least
+    // "name" or "name/".
+    auto id = split(msg.header.frame_id, "/");
+    // discard messages with missing object name
+    if (id.first.empty()) {
+      ROS_WARN_STREAM("Failed to deduce an object name from the frame_id "
+                      << msg.header.frame_id);
+      return;
+    }
+    // try to locate the object in the database
+    std::shared_ptr<StaticObject> object;
+    auto obj_it = database_.find(id.first);
+    if (obj_it == database_.end()) {
+      // create the object if it does not exist yet
+      const auto& prefab = id.second.empty() ? id.first : id.second;
+      object.reset(new StaticObject(id.first, prefab));
+      database_[id.first] = object;
+      bridge_->addStaticObject(object);
+    } else {
+      // since the object exists, just grab it
+      object = obj_it->second;
+    }
+    // update the object
+    object->setPosition(ros2flightmare(msg.pose.position));
+    object->setQuaternion(ros2flightmare(msg.pose.orientation));
+  }
+};
+
+
+int main(int argc, char* argv[]) {
+  // initialize ROS
+  ros::init(argc, argv, "objects_example");
+  ros::NodeHandle nh("");
+  ros::NodeHandle pnh("~");
+  ros::Rate rate(30.0);
+
+  // Flightmare(Unity3D)
+  std::shared_ptr<UnityBridge> unity_bridge_ptr = UnityBridge::getInstance();
+  unity_bridge_ptr->addQuadrotor(std::make_shared<Quadrotor>());
+  SceneID scene_id{UnityScene::INDUSTRIAL};
+  bool unity_ready = unity_bridge_ptr->connectUnity(scene_id);
+  ROS_WARN_COND(!unity_ready, "Failed to connect to Unity3D");
+
+  ObjectDatabase db(pnh, unity_bridge_ptr);
+
+  // Print the usage instructions since the way this node works is
+  // not that intuitive (at least the first time!)
+  ROS_INFO_STREAM(
+    "\n\n------------- USAGE -------------\n\n"
+    "You can publish on the topic " +
+      db.getTopic() +
+      " messages of type "
+      "geometry_msgs/PoseStamped in order to add and move static objects "
+      "around.\n"
+      "To select an object, you must use the frame_id of the message, which "
+      "should "
+      "take the form 'name[/prefab]'. If the object does not exist yet, it is "
+      "created and added to the simulation. If only the name is given, then it "
+      "is "
+      "also used as type. Otherwise, the explicit type gien after the '/' is "
+      "used."
+      "\n\nA couple of example messages:\n\n"
+      "Add object 'cube' of type 'Transparen_Cube':\n"
+      "rostopic pub -1 "
+    << db.getTopic()
+    << " geometry_msgs/PoseStamped \"{header: "
+       "{seq: 0, stamp: {secs: 0, nsecs: 0}, frame_id: "
+       "'cube/Transparen_Cube'}, "
+       "pose: {position: {x: -3, y: 0, z: 1.5}, orientation: {x: 0, y: 0, z: "
+       "0, w: 1}"
+       "}}\""
+       "\n\nChange the position of 'cube':\n"
+       "rostopic pub -1 "
+    << db.getTopic()
+    << " geometry_msgs/PoseStamped \"{header: "
+       "{seq: 0, stamp: {secs: 0, nsecs: 0}, frame_id: 'cube'}, pose: "
+       "{position: "
+       "{x: -1.5, y: 0, z: 1.5}, orientation: {x: 0, y: 0, z: 0, w: 1}}}\""
+       "\n\nAdd object 'rpg_gate' of type 'rpg_gate':\n"
+       "rostopic pub -1 "
+    << db.getTopic()
+    << " geometry_msgs/PoseStamped \"{header: "
+       "{seq: 0, stamp: {secs: 0, nsecs: 0}, frame_id: 'rpg_gate'}, pose: "
+       "{position: "
+       "{x: 3, y: 0, z: 1.5}, orientation: {x: 0, y: 0, z: 0, w: 1}}}\"");
+
+  FrameID frame_id = 0;
+  while (ros::ok() && unity_ready) {
+    ros::spinOnce();
+    unity_bridge_ptr->getRender(frame_id);
+    unity_bridge_ptr->handleOutput();
+    frame_id += 1;
+    rate.sleep();
+  }
+
+  return 0;
+}