Get Started Communicating with the Unreal Engine Visualization Environment

You can set up communication with Unreal Engine^® by using the Simulation 3D Message Get and Simulation 3D Message Set blocks:

• Simulation 3D Message Get receives data from the Unreal Engine environment.

• Simulation 3D Message Set sends data to the Unreal Engine environment.

To use the blocks and communicate with Unreal Engine, make sure you install the Vehicle Dynamics Blockset™ Interface for Unreal Engine Projects support package. For more information, see Install Support Package and Configure Environment.

Next, follow these workflow steps to set up the Simulink^® model and the Unreal Engine environment and run a simulation.

Workflow		Description
Set Up Simulink Model to Send and Receive Data		Configure the Simulation 3D Message Get and Simulation 3D Message Set blocks in Simulink to send and receive the cone location from Unreal® Editor. The steps provides the general workflow for communicating with the editor. The Simulation 3D Message Get and Simulation 3D Message Set blocks can send and receive these data types: double, single, int8, uint8, int16, uint16, int32, uint32, and Boolean. The Simulation 3D Actor Transform Set and Simulation 3D Actor Transform Get blocks can send and receive only the single data type.
Set Up Unreal Engine to Send and Receive Data	C++ Workflow: Set Up Unreal Engine to Send and Receive Data	Specific Unreal C++ workflow to send and receive Simulink cone location data. Simulation 3D Message Get receives data from an Unreal Engine environment C++ actor class. In this example workflow, you use the block to receive the cone location from Unreal Editor. Simulation 3D Message Set sends data to an Unreal Engine C++ actor class. In this example, you use the block to set the initial cone location in the Unreal Editor. To follow this workflow, you should be comfortable coding with C++ in Unreal Engine. Make sure that your environment meets the minimum software requirements described in Unreal Engine Simulation Environment Requirements and Limitations.
	Blueprint Workflow: Set Up Unreal Engine to Send and Receive Data	Generalized Unreal Editor blueprint workflow to send and receive Simulink data.
Run Simulation		After you set up the Simulink model and Unreal Editor environment, run a simulation.

Set Up Simulink Model to Send and Receive Data

Step 1: Install Support Package

If you have already downloaded and installed Unreal Engine and the Vehicle Dynamics Blockset Interface for Unreal Engine Projects support package, go to the next step.

To install and configure the support package, see Install Support Package and Configure Environment.

Before installing the support package, make sure that your environment meets the minimum software and hardware requirements described in Unreal Engine Simulation Environment Requirements and Limitations.

Note

Make sure to launch Unreal Engine from Simulink.

Step 2: Set Up Simulink Model

Open a new Simulink model. Connect the blocks as shown.

Step 3: Configure Blocks

Use these block settings to configure blocks to send and receive cone data from the Unreal Editor.

Block	Parameter Settings
Constant	Constant value — [100,10,50] Sets the initial cone location in the Unreal Editor coordinate system (in cm, left-handed, in Z-up coordinate system) Interpret vector parameters as 1-D — off Output data type — single
Data Type Conversion	Output data type — single
Simulation 3D Scene Configuration	Scene Source — Unreal Editor Project — Project path Path to project, for example the support package project.C:\Local\AutoVrtlEnv\AutoVrtlEnv.uproject Open Unreal Editor — Select to open the editor
Simulation 3D Message Get	Signal name, SigName — ConeLocGet Data type, DataType — single Message size, MsgSize — [1 3] Sample time — -1
Simulation 3D Message Set	Signal name, SigName — ConeLocSet Sample time — -1

C++ Workflow: Set Up Unreal Engine to Send and Receive Data

Step 4: Open Unreal Editor in Editor Mode

1. In your model, open the Simulation 3D Scene Configuration block. Select Open Unreal Editor.

2. Create an Unreal Engine C++ project. Name it TestSim3dGetSet. For steps on creating C++ projects, see Create Empty Project in Unreal Engine.

3. In the Unreal Editor, on the Edit tab, select Plugins. Make sure that the MathWorks Interface plugin is enabled. If it is disabled, enable it.

4. Close the Unreal Editor.

5. If Visual Studio^® is not open, open it.

6. In Visual Studio, add the MathWorksSimulation dependency to the TestSim3dGetSet project build file.

   • In the Solution Explorer, the project build file, TestSim3dGetSet.Build.cs, is located in this folder: ...Games\TestSim3dGetSet\Source\TestSim3dGetSet.

   • In the build file, edit line 11 to add the MathWorksSimulation dependency:

     PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", 
     "Engine", "InputCore", "MathWorksSimulation"}); 

7. Save the change and close the TestSim3dGetSet project.

8. Close Visual Studio.

9. In your model, open the Simulation 3D Scene Configuration block.

   1. Set Project to Your_Project_path\TestSim3dGetSet.uproject.

   2. Select Open Unreal Editor.

Step 5: Create Actor Class

1. In the Unreal Editor, on the Content Browser tab (located in the bottom left), under Settings, select Show Engine Content and Show Plugin Content.

   

2. In the Unreal Editor, from the MathWorks Interface C++ classes directory, select Sim3dActor.

   

   Right-click and select Create C++ class derived from Sim3dActor.

   

3. Name the new Sim3dActor SetGetActorLocation. Select Public. Click Create Class.

4. Close the Unreal Editor.

Step 6: Open SetGetActorLocation.h

Visual Studio opens with new C++ files in the project folder:

• SetGetActorLocation.h

• SetGetActorLocation.cpp

Make sure you close the Unreal Editor.

In Visual Studio, build the solution TestSim3dGetSet:

1. In the Solution Explorer, under the Games folder, right-click TestSim3dGetSet.

2. Select Build.

3. After the solution builds, open SetGetActorLocation.h. Edit the file as shown.

    Replacement Code: SetGetActorLocation.h

   This is the replacement code for SetGetActorLocation.h.

   // Copyright 2019-2022 The MathWorks, Inc.
   
   #pragma once
   
   #include "CoreMinimal.h"
   #include "Sim3dActor.h"
   #include "SetGetActorLocation.generated.h"
   
   UCLASS()
   class TESTSIM3DGETSET_API ASetGetActorLocation : public ASim3dActor
   {
   	GENERATED_BODY()
   	
   	void *SignalReader;
   	void *SignalWriter;
   
   public:	
   	// Sets default values for this actor's properties
   	ASetGetActorLocation();
   
   	virtual void Sim3dSetup() override;
   	virtual void Sim3dRelease() override;
   	virtual void Sim3dStep(float DeltaSeconds) override;
   };
   

   Note

   The class name must match the project name with _API appended to the end in SetGetActorLocation.h.

Step 7: Open SetGetActorLocation.cpp

Open SetGetActorLocation.cpp and replace the block of code.

 Replacement Code: Set Pointer to Parameter

This code allows you to set a pointer to the parameter Signal Name parameter for the Simulink blocks Simulation 3D Message Set and Simulation 3D Message Get, respectively.

// Sets default values
ASetGetActorLocation::ASetGetActorLocation():SignalReader(nullptr), SignalWriter(nullptr)
{
}

 Replacement Code: Access Actor Tag Name

The following code allows you to access the tag name of this actor after it is instantiated in the scene with an assigned tag name. The code also initializes the pointers SignalReader and SignalWriter, to initiate a link between Unreal Editor and Simulink. The variables represent these block Signal Name parameter values:

• SignalReaderTag — Simulation 3D Message Set

• SignalWriterTag — Simulation 3D Message Get

void ASetGetActorLocation::Sim3dSetup()
{
Super::Sim3dSetup();
       if (Tags.Num() != 0) {
              unsigned int numElements = 3;
              FString tagName = Tags.Top().ToString();

              FString SignalReaderTag = tagName;
              SignalReaderTag.Append(TEXT("Set"));
              SignalReader = StartSimulation3DMessageReader(TCHAR_TO_ANSI(*SignalReaderTag), sizeof(float)*numElements);

              FString SignalWriterTag = tagName;
              SignalWriterTag.Append(TEXT("Get"));
              SignalWriter = StartSimulation3DMessageWriter(TCHAR_TO_ANSI(*SignalWriterTag), sizeof(float)*numElements);
              }
}

 Additional Code: Read and Write Data During Run Time

Add this code to allow Unreal Engine to read the data value set by Simulation 3D Message Set and then write back to Simulation 3D Message Get during run time. Unreal Engine uses this data to set the location value of the actor.

void ASetGetActorLocation::Sim3dStep(float DeltaSeconds)
{
       unsigned int numElements = 3;
       float array[3];
       int statusR = ReadSimulation3DMessage(SignalReader, sizeof(float)*numElements, array);
       FVector NewLocation;
       NewLocation.X = array[0];
       NewLocation.Y = array[1];
       NewLocation.Z = array[2];
       SetActorLocation(NewLocation);
       float fvector[3] = { NewLocation.X, NewLocation.Y, NewLocation.Z };
       int statusW = WriteSimulation3DMessage(SignalWriter, sizeof(float)*numElements ,fvector);
}

 Additional Code: Stop Simulation

Add this code so that Unreal Engine stops when you press the Simulink stop button. The code destroys the pointer SignalReader and SignalWriter.

void ASetGetActorLocation::Sim3dRelease()
{
       Super::Sim3dRelease();
       if (SignalReader) {
              StopSimulation3DMessageReader(SignalReader);
       }
       SignalReader = nullptr;     

       if (SignalWriter) {
              StopSimulation3DMessageWriter(SignalWriter);
       }
       SignalWriter = nullptr;
}

 Entire Replacement Code: SetGetActorLocation.cpp

This is the entire replacement code for SetGetActorLocation.cpp.

// Copyright 2019-2022 The MathWorks, Inc.
#include "SetGetActorLocation.h"

// Sets default values
ASetGetActorLocation::ASetGetActorLocation():SignalReader(nullptr), SignalWriter(nullptr)
{
}

void ASetGetActorLocation::Sim3dSetup()
{
Super::Sim3dSetup();
       if (Tags.Num() != 0) {
              unsigned int numElements = 3;
              FString tagName = Tags.Top().ToString();

              FString SignalReaderTag = tagName;
              SignalReaderTag.Append(TEXT("Set"));
              SignalReader = StartSimulation3DMessageReader(TCHAR_TO_ANSI(*SignalReaderTag), sizeof(float)*numElements);

              FString SignalWriterTag = tagName;
              SignalWriterTag.Append(TEXT("Get"));
              SignalWriter = StartSimulation3DMessageWriter(TCHAR_TO_ANSI(*SignalWriterTag), sizeof(float)*numElements);
              }
}

void ASetGetActorLocation::Sim3dStep(float DeltaSeconds)
{
       unsigned int numElements = 3;
       float array[3];
       int statusR = ReadSimulation3DMessage(SignalReader, sizeof(float)*numElements, array);
       FVector NewLocation;
       NewLocation.X = array[0];
       NewLocation.Y = array[1];
       NewLocation.Z = array[2];
       SetActorLocation(NewLocation);
       float fvector[3] = { NewLocation.X, NewLocation.Y, NewLocation.Z };
       int statusW = WriteSimulation3DMessage(SignalWriter, sizeof(float)*numElements ,fvector);
}

void ASetGetActorLocation::Sim3dRelease()
{
       Super::Sim3dRelease();
       if (SignalReader) {
              StopSimulation3DMessageReader(SignalReader);
       }
       SignalReader = nullptr;     

       if (SignalWriter) {
              StopSimulation3DMessageWriter(SignalWriter);
       }
       SignalWriter = nullptr;
}

Step 8: Build the Visual Studio Project and Open Unreal Editor

In Visual Studio, select Debug > Start Debugging or press F5 to run the TestSim3dGetSet solution. The Unreal Editor opens.

Note

In the Unreal Editor, save the current level by clicking Save Current (located in the top left) and name it TestMap. Add this level as default to Project Settings by clicking on Edit > Project Settings > Maps&Modes. Then select TestMap as the default value for the Editor Startup Map and Game Default Map. Close Project Settings to save the default values.

Step 9: Place and Check Actor

1. In the Unreal Editor, find the Set Get Actor Location in the Place Actor tab, and place it in the TestMap.

   

2. On the Outliner tab, check that the new instantiated actor, SetGetActorLocation, is listed.

   

Step 10: Add Mesh

Click the actor that you created in Step 9: Place and Check Actor.

1. In the Details panel, click Add, to add a mesh to the actor SetGetActorLocation. Choose Cone as the default mesh.

   

2. Find the property Tags for actor SetGetActorLocation. Add a tag by clicking on the plus sign next to 0 Array elements. Name it ConeLoc.

   

   Tip

   For Simulink to communicate with the Unreal Engine environment, the C++ code appends Get and Set to the tag name to match the Signal name parameter set in the Simulation 3D Message Get and Simulation 3D Message Set blocks.

Step 11: Set Cone Location

On the Details tab, click Cone. Set the cone to X = 0.0, Y = 0.0, and Z = 0.0. Also set the actor Mobility property to Movable.

Step 12: Set Parent Class and Save Scene

Set the parent class.

1. Under Blueprints, click Open Level Blueprint, and select Class Settings.

   

2. In the Class Options, set Parent Class to Sim 3d Level Script Actor.

   

Save the Unreal Editor scene.

Step 13: Run Simulation

Run the simulation. Go to Run Simulation.

Reference: C++ Functions for Sending and Receiving Simulink Data

Call these C++ functions from Sim3dSetup, Sim3dStep, and Sim3dRelease to send and receive Simulink data.

To	C++ Functions
Receive data	StartSimulation3DMessageReader
	ReadSimulation3DMessage
	StopSimulation3DMessageReader
Send data	StartSimulation3DMessageWriter
	WriteSimulation3DMessage
	StopSimulation3DMessageWriter

Blueprint Workflow: Set Up Unreal Engine to Send and Receive Data

Step 4: Configure Scenes to Receive Data

To use the Simulation 3D Message Set block, you must configure scenes in the Unreal Engine environment to receive data from the Simulink model:

1. In the Unreal Editor, instantiate the Sim3DGet actor that corresponds to the data type you want to receive from the Simulink model. This example shows the Unreal Editor Sim3DGet data types. Select Sim 3d Get Float.

   

2. In the Details panel, specify an actor tag name that matches the Simulation 3D Message Set block Signal name parameter.

3. In the Details panel, set Read Array Float Max Num Element to 3.

   

4. Navigate to the Level Blueprint.

5. Right-click the graph and find the blueprint method for the Sim3DGet actor class based on the data type and size that you want to receive from the Simulink model.

   For this example, the array size is 3. The unreal editor diagram shows that Read Vector Float is the method for Sim3dGetFloat actor class that receives float data type of array size 3.

   

   Note

   Depending on the number of elements you need to read, use one of these methods:

   • Read Scalar <DATA_TYPE> — To read 1 element.

   • Read Vector <DATA_TYPE> — To read a vector of 3 elements.

   • Read Array <DATA_TYPE> — To read an array of X elements.

6. Compile and save the scene.

Step 5: Configure Scenes to Send Data

To configure scenes in the Unreal Engine environment to send data to the Simulink model:

1. In the Unreal Editor, instantiate the Sim3DSet actor that corresponds to the data type you want to send to the Simulink model. This example shows the Unreal Editor Sim3DSet data types. Select Sim 3d Set Float.

   

2. Specify an actor tag name that matches the Simulation 3D Message Get block Signal name parameter and set Write Array Float Max Num Element to 3.

3. Navigate to the Level Blueprint.

4. Find the blueprint method for the Sim3DSet actor class based on the data type and size specified by the Simulation 3D Message Get block Data type and Message size parameters.

   For this example, the array size is 3. The Unreal Editor diagram shows that Write Vector Float is the method for the Sim3DSetFloat actor class that sends float data type of array size 3.

   

   Depending on the number of elements you need to write, use one of these methods:

   Note

   • Write Scalar <DATA_TYPE> — To write 1 element.

   • Write Vector <DATA_TYPE> — To write a vector of 3 elements.

   • Write Array <DATA_TYPE> — To write an array of X elements.

5. Compile and save the scene.

Step 6: Create Blueprint

In the Unreal Editor, create a level blueprint connecting the Get and Set actors.

1. Set the actor tag values.

   • Sim3dGetFloat — Simulation 3D Message Set block Signal name, SigName parameter value, for example ConeLocSet

   • Sim3dSetFloat — Simulation 3D Message Get block Signal name, SigName parameter value, for example ConeLocGet

2. Set the parent class.

   1. Under Blueprints, click Open Level Blueprint, and select Class Settings.

      

   2. In the Class Options, set Parent Class to Sim 3d Level Script Actor.

      

3. In the level blueprint, make the connections, for example:

   

Step 7: Run Simulation

Run the simulation. Go to Run Simulation.

Run Simulation

After you configure the Simulink model and Unreal Editor environment, you can run the simulation. Change the Constant value in the Simulink model during run time to see the corresponding cone location change in the Unreal Editor environment.

Note

At the BeginPlay event, Simulink does not receive data from the Unreal Editor. Simulink receives data at Tick events. In pause mode, Read Vector Float is still invoked at Tick events, but Simulink does not send messages.

Run the simulation.

1. In the Simulink model, click Run.

   Because the source of the scenes is the project opened in the Unreal Editor, the simulation does not start.

2. Verify that the Diagnostic Viewer window in Simulink displays this message:

   In the Simulation 3D Scene Configuration block, you set the scene source to 'Unreal Editor'. In Unreal Editor, select 'Play' to view the scene.

   This message confirms that Simulink has instantiated the vehicles and other assets in the Unreal Engine 3D environment.

3. In the Unreal Editor, click Play. The simulation runs in the scene currently open in the Unreal Editor.

You can send and receive these data types: double, single, int8, uint8, int16, uint16, int32, uint32, boolean. The code in Step 7: Open SetGetActorLocation.cpp reads single data type values (or float values) from Simulink.