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Falken C++ SDK

The C++ SDK is one of the two supported Falken SDKs (C++, Unity). Use the C++ SDK if you are integrating with a C++ game or a game built on a C++ game engine.

To use the SDK, you must be running the service, as described in the service instructions.

Download the C++ SDK on the Releases page, or if you make changes, build it yourself by following the Build the C++ SDK instructions.

Build and Run the Hello Falken Sample

The fastest way to ensure that your setup is working properly is by building and running the Hello Falken sample by following these instructions.

Integrate Falken

Once you verified your setup is working properly with Hello Falken, now it's time to integrate the Falken SDK with your game.

Make sure you've familiarized yourself with Falken Concepts.

Import the SDK

There are two options when importing the SDK: manually or by using cmake.

Import Manually

  1. Add falken_cpp_sdk/include to the include path
  2. Add falken_cpp_sdk library to the linker command line:
  3. Windows:
falken_sdk/libs/CONFIG/falken_cpp_sdk.dll
falken_sdk/libs/CONFIG/falken_cpp_sdk.lib (import library)
  1. macOS:
falken_sdk/libs/falken_cpp_sdk.dylib
  1. Linux:
falken_sdk/libs/falken_cpp_sdk.so
Import into Visual Studio project
  1. Add falken_cpp_sdk/include to the include path; example here.
  2. Add DLL import library falken_sdk/libs/CONFIG/falken_cpp_sdk.lib; example here.
  3. Copy the DLL falken_sdk/libs/CONFIG/falken_cpp_sdk.dll to the executable directory; example here.
Import into Xcode project
  1. Add falken_cpp_sdk/include to the include path; example here.
  2. Add falken_sdk/libs/falken_cpp_sdk.dylib to the link step; example here.

Import Using cmake

  1. Add the falken_sdk directory to CMAKE_MODULE_PATH then find the package using:
find_package(falken REQUIRED)
  1. Link the falken library using:
target_link_libraries(YOUR_TARGET falken_cpp_sdk)

Initialize Falken

For the SDK to properly specify the project ID, API key, and the certificate to connect to the service, the easiest way is to simply copy the falken_config.json that the service launcher generated into the directory where your game binary is located and call:

std::shared_ptr<falken::Service> service = falken::Service::Connect(
  nullptr, nullptr, nullptr);

You can also specify a raw JSON string containing the information from falken_config.json in the third argument of Connect:

std::shared_ptr<falken::Service> service = falken::Service::Connect(
  nullptr, nullptr, kJsonConfig);

Make sure to retain this pointer to the service. If the returned shared_ptr is deallocated or assigned to null, the Falken service will shutdown and destroy all active Sessions, Brains, etc.

Define Actions

Create a class that derives from falken::ActionBase. Members can be of type NumberAttribute, CategoryAttribute or JoystickAttribute.

struct MyActions : public falken::ActionsBase {
    MyActions()
        : FALKEN_NUMBER(throttle, -1.0f, 1.0f),
          FALKEN_JOYSTICK_DELTA_PITCH_YAW(joystick,
                                          falken::kControlledEntityPlayer) {}

    falken::NumberAttribute<float> throttle;
    falken::JoystickAttribute joystick;
};

Joystick attributes represent a 2-axis input device that either controls pitch and yaw or indicates a desired direction in the XZ plane of the controlled object. When joystick actions are present, entity position and rotation observations (see next section) are preprocessed to optimize agent learning. It is therefore important to correctly configure these action types to obtain good performance. Below are a few examples of common control schemes modeled as Joystick actions. Note that if any Joystick action references a camera, a camera entity needs to be provided as part of the observation; see next section.

Third Person Camera-relative controls (e.g., Dark Souls, Mario64 etc.)

// Tomb-raider style controls: left stick controls movement, right stick camera.
struct ThirdPersonAvatarControls : public falken::ActionsBase {
  ThirdPersonAvatarControls()
      : FALKEN_JOYSTICK_DIRECTION_XZ( // Controls player movement in XZ plane.
            move,
            falken::kControlledEntityPlayer,  // Controls player-XZ movement.
            falken::kControlFrameCamera),     // Input is relative to the camera.
        FALKEN_JOYSTICK_DELTA_PITCH_YAW( // Controls camera pitch and yaw.
            aim,
            falken::kControlledEntityCamera) // Input controls the camera.
   {}


  falken::JoystickAttribute move;
  falken::JoystickAttribute aim;
};

Twin Stick Controls (e.g., Geometry Wars)

struct TwinStickControls : public falken::ActionsBase {
  TwinStickControls()
      : FALKEN_JOYSTICK_DIRECTION_XZ( // Controls player movement in XZ plane.
            move,
            falken::kControlledEntityPlayer, // Controls player-XZ movement.
            falken::kControlFrameWorld),     // Input is world-relative.
        FALKEN_JOYSTICK_DIRECTION_XZ( // Controls XZ aim direction.
            aim,
            falken::kControlledEntityPlayer, // Controls player-XZ aim.
            falken::kControlFrameWorld)      // Input is world-relative.
  {}

  falken::JoystickAttribute move;
  falken::JoystickAttribute aim;
};

First-Person Shooter Controls (e.g., Quake)

struct FPSControls : public falken::ActionsBase {
  FPSControls()
      : FALKEN_JOYSTICK_DIRECTION_XZ( // Controls player-XZ movement.
            move,
            falken::kControlledEntityPlayer, // Controls player-XZ movement.
            falken::kControlFramePlayer),    // Input is relative to the player.
        FALKEN_JOYSTICK_DELTA_PITCH_YAW(
            aim,
            falken::kControlledEntityCamera) // Aims the first-person camera.
  {}

  falken::JoystickAttribute move;
  falken::JoystickAttribute aim;
};

Define Observations

Create a struct that derives from falken::ObservationBase. You can add members of type NumberAttribute, CategoryAttribute, and FeelersAttribute and they will be treated as part of the default Player entity. ObservationBase has fields for position and rotation, which indicate the position and rotation of the player. Falken expects a left-handed coordinate system in which the y axis points up, the x-axis points towards the right, and the z-axis is aligned with the forward direction of entities.

struct MyObservations : public falken::ObservationsBase {
    MyObservations()
      : FALKEN_NUMBER(my_float, -1.0f, 1.0f) {}

    falken::NumberAttribute<float> my_float;
};

You can also define new types of Entity (like Enemy or Goal) by creating classes that derive from falken::EntityBase. Note that entities have default attributes for position and rotation.

struct Enemy : public falken::EntityBase {
    Enemy(falken::EntityContainer& container, const char* name)
      : falken::EntityBase(container, name),
        FALKEN_NUMBER(my_float, -1.0f, 1.0f) {}

    falken::NumberAttribute<float> my_float;
};

And add instances of them as attributes for your observations.

struct MyObservations : public falken::ObservationsBase {
    MyObservations()
      : FALKEN_NUMBER(my_float, -1.0f, 1.0f),
        FALKEN_ENTITY(my_enemy) {}

    falken::NumberAttribute<float> my_float;
    Enemy my_enemy;
};

Note that if you used Joystick actions that reference a camera, either by defining a Joystick action that controls the camera or by using a camera reference frame, you will need to add an entity named camera to your observations, so Falken can know about the position and orientation of the camera as well as the player (note that position and rotation of the player are set using the position and orientation members of ObservationsBase):

struct MyObservations : public falken::ObservationsBase {
    MyObservations()
      : FALKEN_NUMBER(unrelated_observation, -1.0f, 1.0f),
        FALKEN_ENTITY(camera) {}

    falken::NumberAttribute<float> unrelated_observation;
    falken::EntityBase camera;
};

Create a Brain

Define a BrainSpec type that binds your Actions and Observations.

using MyBrainSpec = falken::BrainSpec<MyObservations, MyActions>;

Call Falken to create an instance of the Brain.

std::unique_ptr<falken::Brain<MyBrainSpec>> brain =
    service->CreateBrain<BrainSpec>("MyBrain");

Make sure to retain this pointer to the brain. If the returned unique_ptr is deallocated or assigned to null, the Brain will be unloaded.

Start a Session. Start an Episode.

Start a new Session using the Brain instance you created above and then use the Session to start your first Episode.

std::unique_ptr<falken::Session> session =
    brain->StartSession(falken::Session::kTypeInteractiveTraining, kMaxSteps);

std::unique_ptr<falken::Episode> episode = session->StartEpisode();

Step the Episode

auto& brain_spec = brain->brain_spec();
// Set attributes in brain_spec.observations from game state.
if (human_control) {
  // Set attributes in brain_spec.actions.
}

episode->Step();

if (episode->completed()) {
  episode = nullptr;
  // Reset your game as we've hit the maximum number of steps.
} else if (!human_control) {
  // Apply brain_spec.actions to your game.
}

End the Episode. Reset the Game.

episode->Complete(falken::Episode::kCompletionStateSuccess);
// Game specific reset logic.

Ending one Session.

session->Stop();

Build the C++ SDK

Desktop Platforms

  1. Make a new subdirectory called build in the sdk/cpp directory and go into that directory:

    cd sdk/cpp
mkdir build
cd build

  2. Configure cmake:

    1. Windows
    cmake -A x64 ..
    1. macOS:
    cmake -GXcode ..
    1. Linux:
    cmake ..

  3. Build the SDK: Note the number of parallel build tasks 4 is required on macOS when building with Xcode other platforms this can be omitted.

    This can be changed to a number that matches the number of CPUs in your system to speed up builds.

    1. Windows
    cmake --build . --config Release -j
    1. macOS
    cmake --build . --config Release -j 4
    1. Linux
    cmake --build . -j

  4. Package the SDK

Package the SDK to generate a zip file that contains build artifacts to use in your projects.

  1. Windows
cpack -G ZIP -C Release
  1. macOS (Xcode)
cpack -G ZIP -C Release
  1. Linux
cpack -G ZIP -C Release
  1. Make sure to unzip the zip file before including the SDK using cmake.

Build artifacts are stored under build/lib (Linux / macOS) and build/bin (Windows DLL)

On macOS and Windows it's also possible to open the generated Xcode or Visual Studio project and build from the IDE by selecting the falken_cpp_sdk build target.

Android Platforms

  1. Open the sdk/cpp folder with Android Studio.
  2. Set FALKEN_PYTHON with the path of the installed Python3 interpreter in sdk/cpp/gradle.properties.
  3. Set FALKEN_CMAKE_VERSION with the semantic version number of the installed CMake in sdk/cpp/gradle.properties.
  4. Sync project.
  5. Build project.
  6. Close Android Studio.
  7. Package the SDK to generate a zip file that contains build artifacts to use in your projects. From a terminal located in sdk/cpp, execute the following commands: 
    cd .cxx/cmake/release/arm64-v8a
cpack -G ZIP -C Release

Build artifacts are stored under .cxx/cmake/release/arm64-v8a/build/packaging/ (Linux / macOS) and .cxx\cmake\release\arm64-v8a\build\packaging\ (Windows).