cd UnrealEngine
./Setup.sh
./GenerateProjectFiles.sh
编译完成后，启动项目并接受重建
（如果不进行上述步骤可能会遇到虚幻引擎自建项目打不开或遇到engine modules are out of date and cannot be compiled while the engine is running的情况）
创建一个新的C++虚幻项目，或打开现有项目
在内容浏览器中查找（在内容浏览器的右下角启用“查看选项”>“显示插件内容”）
点击“添加/导入”按钮下方的三条线按钮，展开左侧区域
选中“ROSIntegration“>“Classes”，右键ROSIntegrationGameInstance，点击下图黄色选项
打开新的C++类/蓝图对象，并更改ROSBridgeSeverHost 和ROSBridgeServerPort，如果是本地运行的ROSBridge，则改为127.0.0.1即可
打开“地图和模式”>“项目设置”，并将游戏实例设置为与新的游戏实例对象匹配，比如MyROSIntegrationGameInstance，而不是插件中的ROSIntegrationGameInstance
使用Ctrl + Shift + S保存所有更改
3、使用ROSIntegration
要进行与 ROS 的简单发布/订阅通信，需要在创建一个新的C++ Actor，而非中文的角色（Charactor）。
接着创建 SamplePubliser
SamplePublisher.h
#include "ROSIntegration/Classes/RI/Topic.h"
#include "ROSIntegration/Classes/ROSIntegrationGameInstance.h"
#include "ROSIntegration/Public/std_msgs/String.h"
注意：上述代码必须在#include "SamplePublisher.generated.h"之前，否则会报错
SamplePublisher.cpp
// Initialize a topic
UTopic *ExampleTopic = NewObject<UTopic>(UTopic::StaticClass());
UROSIntegrationGameInstance* rosinst = Cast<UROSIntegrationGameInstance>(GetGameInstance());
ExampleTopic->Init(rosinst->ROSIntegrationCore, TEXT("/example_topic"), TEXT("std_msgs/String"));
// (Optional) Advertise the topic
ExampleTopic->Advertise();
// Publish a string to the topic
TSharedPtr<ROSMessages::std_msgs::String> StringMessage(new ROSMessages::std_msgs::String("This is an example"));
ExampleTopic->Publish(StringMessage);
注意：上述代码放置在BeginPlay()函数中
进入unreal_engine_project/Source/unreal_engine_project目录（替换 unreal_engine_project 为真实的项目名称），打开unreal_engine_project.Build.cs文件
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" });
添加ROSIntegrationy依赖，形如：
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "ROSIntegration" });
进入ROS工作空间的src目录，创建测试功能包：
catkin_create_pkg ue_test std_msgs rospy roscpp
编译并source：
catkin_make
source devel/setup.bash
创建一个监听者cpp文件：
cd ue_test/src
touch listener.cpp
打开cpp并键入如下代码：
#include "ros/ros.h"
#include "std_msgs/String.h"
* This tutorial demonstrates simple receipt of messages over the ROS system.
void chatterCallback(const std_msgs::String::ConstPtr& msg)
ROS_INFO("I heard: [%s]", msg->data.c_str());
int main(int argc, char **argv)
* The ros::init() function needs to see argc and argv so that it can perform
* any ROS arguments and name remapping that were provided at the command line.
* For programmatic remappings you can use a different version of init() which takes
* remappings directly, but for most command-line programs, passing argc and argv is
* the easiest way to do it. The third argument to init() is the name of the node.
* You must call one of the versions of ros::init() before using any other
* part of the ROS system.
ros::init(argc, argv, "listener");
* NodeHandle is the main access point to communications with the ROS system.
* The first NodeHandle constructed will fully initialize this node, and the last
* NodeHandle destructed will close down the node.
ros::NodeHandle n;
* The subscribe() call is how you tell ROS that you want to receive messages
* on a given topic. This invokes a call to the ROS
* master node, which keeps a registry of who is publishing and who
* is subscribing. Messages are passed to a callback function, here
* called chatterCallback. subscribe() returns a Subscriber object that you
* must hold on to until you want to unsubscribe. When all copies of the Subscriber
* object go out of scope, this callback will automatically be unsubscribed from
* this topic.
* The second parameter to the subscribe() function is the size of the message
* queue. If messages are arriving faster than they are being processed, this
* is the number of messages that will be buffered up before beginning to throw
* away the oldest ones.
ros::Subscriber sub = n.subscribe("/example_topic", 1000, chatterCallback);
* ros::spin() will enter a loop, pumping callbacks. With this version, all
* callbacks will be called from within this thread (the main one). ros::spin()
* will exit when Ctrl-C is pressed, or the node is shutdown by the master.
ros::spin();
return 0;
在CMakeLists.txt添加：
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
add_dependencies(listener listener)
4、测试ROSIntegration
启动rosbridge
roslaunch rosbridge_server rosbridge_tcp.launch bson_only_mode:=True
运行新建功能包的监听者
# rosrun <your package> talker
rosrun ue_test talker
将在UE中新建的SamplePublisher托入三维世界中，并点击运行
此时可以看到：
[INFO] [1588662504.536355639]: I heard: [This is an example]
恭喜你成功配置并运行了ROSIntegration！！！
三、ROSIntegrationVision下载与配置运行
1、虚幻引擎配置修改
在PATH_TO_UNREAL/Engine/Source/Programs/UnrealBuildTool/Platform/Linux/LinuxToolChain.cs中找到GetCLArguments_Global函数，并在其中添加语句Result += " -mf16c";，形如：
protected virtual string GetCLArguments_Global(CppCompileEnvironment CompileEnvironment)
string Result = "";
// build up the commandline common to C and C++
Result += " -c";
Result += " -pipe";
Result += " -mf16c";
if (ShouldUseLibcxx(CompileEnvironment.Architecture))
Result += " -nostdinc++";
Result += " -I" + "ThirdParty/Linux/LibCxx/include/";
Result += " -I" + "ThirdParty/Linux/LibCxx/include/c++/v1";
而后重新编译虚幻引擎（注意如下语句必须都执行才算是重新编译）：
cd UnrealEngine
./Setup.sh
./GenerateProjectFiles.sh
2、配置ROSIntegrationVision
使用git命令下载ROSIntegrationVision，放置在虚幻引擎项目文件Plugins文件夹下
cd unreal_engine_project # 替换 unreal_engine_project 为项目目录文件夹路径
mkdir Plugins # 如果没有 Plugins 文件夹则手动创建
cd Plugins
git clone https://github.com/code-iai/ROSIntegrationVision/.git
如果你是在Linux上编译虚幻引擎4而非Windows，则在打开项目时可能会遇到
Building forest2Editor...
Performing 3 actions (6 in parallel)
[1/3] Compile Module.ROSIntegrationVision.cpp
In file included from .../Plugins/ROSIntegrationVision/Intermediate/Build/Linux/B4D820EA/UE4Editor/Development/ROSIntegrationVision/Module.ROSIntegrationVision.cpp:6:
.../Plugins/ROSIntegrationVision/Source/ROSIntegrationVision/Private/VisionComponent.cpp:754:4: error: use of undeclared identifier '_mm_div_epi16'; did you mean '_mm_min_epi16'?
_mm_div_epi16(
^~~~~~~~~~~~~
_mm_min_epi16
/home/pisces/Gitware/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/lib/clang/10.0.1/include/emmintrin.h:2412:1: note: '_mm_min_epi16' declared here
_mm_min_epi16(__m128i __a, __m128i __b)
1 error generated.
LogInit: Warning: Still incompatible or missing module: ROSIntegrationVision
这是由于官方参考了Windows for UVisionComponent上的编译问题：：convertDepth #28这一问题的回答，将源码改为了适配Windows的环境，但在Ubuntu18.04中并不存在_mm_div_epi16这一函数
因而，改变代码
void UVisionComponent::convertDepth(const uint16_t *in, __m128 *out) const
const size_t size = (Width * Height) / 4;
for (size_t i = 0; i < size; ++i, in += 4, ++out)
// Divide by 100 here in order to convert UU (cm) into ROS units (m)
*out = _mm_cvtph_ps(
_mm_div_epi16(
_mm_set_epi16(0, 0, 0, 0, *(in + 3), *(in + 2), *(in + 1), *(in + 0)),
_mm_set_epi16(100, 100, 100, 100, 100, 100, 100, 100)
);// / 100;
void UVisionComponent::convertDepth(const uint16_t *in, __m128 *out) const
const size_t size = (Width * Height) / 4;
for (size_t i = 0; i < size; ++i, in += 4, ++out)
// Divide by 100 here in order to convert UU (cm) into ROS units (m)
*out = _mm_cvtph_ps(_mm_set_epi16(
0, 0, 0, 0, *(in + 3), *(in + 2), *(in + 1), *(in + 0))) / 100;
即可成功自动编译打开项目
3、使用ROSIntegrationVision
在内容浏览器ROSIntegrationVision/ROSIntegrationVision/Private中包含VisionActor C++文件，将其托入三维世界中即可现实摄像头图像信息
注意：使用时需要先在VisionActor.cpp中作如下修改
AVisionActor::AVisionActor() : AActor()
UE_LOG(LogTemp, Warning, TEXT("VisionActor CTOR"));
// Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it.
PrimaryActorTick.bCanEverTick = true;
RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("Root"));
SetRootComponent(RootComponent);
vision = CreateDefaultSubobject<UVisionComponent>(TEXT("Vision"));
vision->DisableTFPublishing = true; // 添加
//vision->ParentLink = "/world"; 注释掉
vision->ParentLink = "desired_link"; // 添加
vision->SetupAttachment(RootComponent);
将ROSIntegrationVision插件中的Binaries和Intermediate文件夹删除，重新打开项目，使引擎重新编译插件
如果在运行rosbridge时遇到如下问题
可以修改ROSIntegration/Source/ROSIntegration/Private/Conversion/Messages/sensor_msgs/SensorMsgsCameraInfoConverter.h文件
static void _bson_append_camera_info(bson_t *b, const ROSMessages::sensor_msgs::CameraInfo *msg)
// assert(CastMsg->D.Num() == 5); // TODO: use Unreal assertions
assert(CastMsg->K.Num() == 9); // TODO: use Unreal assertions
assert(CastMsg->R.Num() == 9);
assert(CastMsg->P.Num() == 12);
UStdMsgsHeaderConverter::_bson_append_child_header(b, "header", &msg->header);
BSON_APPEND_INT32(b, "height", msg->height);
BSON_APPEND_INT32(b, "width", msg->width);
BSON_APPEND_UTF8(b, "distortion_model", TCHAR_TO_UTF8(*msg->distortion_model));
_bson_append_double_tarray(b, "d", msg->D);
_bson_append_double_tarray(b, "k", msg->K);
_bson_append_double_tarray(b, "r", msg->R);
_bson_append_double_tarray(b, "p", msg->P);
BSON_APPEND_INT32(b, "binning_x", msg->binning_x);
BSON_APPEND_INT32(b, "binning_y", msg->binning_y);
USensorMsgsRegionOfInterestConverter::_bson_append_child_roi(b, "roi", &msg->roi);
static void _bson_append_camera_info(bson_t *b, const ROSMessages::sensor_msgs::CameraInfo *msg)
// assert(CastMsg->D.Num() == 5); // TODO: use Unreal assertions
assert(CastMsg->K.Num() == 9); // TODO: use Unreal assertions
assert(CastMsg->R.Num() == 9);
assert(CastMsg->P.Num() == 12);
UStdMsgsHeaderConverter::_bson_append_child_header(b, "header", &msg->header);
BSON_APPEND_INT32(b, "height", msg->height);
BSON_APPEND_INT32(b, "width", msg->width);
BSON_APPEND_UTF8(b, "distortion_model", TCHAR_TO_UTF8(*msg->distortion_model));
_bson_append_double_tarray(b, "D", msg->D); // 替换
_bson_append_double_tarray(b, "K", msg->K); // 替换
_bson_append_double_tarray(b, "R", msg->R); // 替换
_bson_append_double_tarray(b, "P", msg->P); // 替换
BSON_APPEND_INT32(b, "binning_x", msg->binning_x);
BSON_APPEND_INT32(b, "binning_y", msg->binning_y);
USensorMsgsRegionOfInterestConverter::_bson_append_child_roi(b, "roi", &msg->roi);
如果相机图象FPS较低，可以考虑修改VisionComponent.cpp中 Framerate(1) 为 Framerate(100)
UVisionComponent::UVisionComponent() :
Width(640),
Height(480),
Framerate(100), // change 1 to 100
UseEngineFramerate(false),
ServerPort(10000),
FrameTime(1.0f / Framerate),
TimePassed(0),
ColorsUsed(0)
四、参考资料
[1] code-iai/ROSIntegration markdown说明文档及issues
[2] code-iai/ROSIntegrationVision markdown说明文档及issues
[3] ROS Communication Sample on Unreal Engine Using ROSIntegration
[4] upgrade c++ project from ue 4.24 to 4.25 under Linux
部分图片来源于网络
转载请注明出处！
本篇发布在以下博客或网站：
双鱼座羊驼 - 知乎 (zhihu.com)
双鱼座羊驼的博客_CSDN博客
双鱼座羊驼 - SegmentFault 思否
双鱼座羊驼 的个人主页 - 动态 - 掘金 (juejin.cn)
双鱼座羊驼 - 博客园 (cnblogs.com)
