Bumblebee

Bumblebee is a 2D game engine powered by C++, Box2D, SDL and IMGui and aims to provide a simple interface to create 2D games for the Windows platform.

Engine Architecture

GameObject Class

The gameobject should be used to construct all visible gameobjects in the scene. Gameobject is final because unique game objects should be constructed by adding different components to the game object that provide logic and functionality to set game object. For objects that don't require rendering or a transform, you can use a SceneObject instead of GameObject.

namespace BTEngine
{
	class BaseComponent;
	class Texture2D;

	class GameObject final : public SceneObject
	{
	public:
		GameObject();
		~GameObject(); // no virtual because class is final
		GameObject(const GameObject & other) = delete;
		GameObject(GameObject && other) = delete;
		GameObject& operator=(const GameObject & other) = delete;
		GameObject& operator=(GameObject && other) = delete;

		void Update() override;
		void FixedUpdate() override;
		void Render() const override;
		void Initialize() override;
		void OnAttached();
		void OnDetached();
		void SetTag(const std::string& tag);
		const std::string& GetTag() const;

		template <typename T> T* AddComponent();
		template <typename T> T* GetComponent() const;
		template <typename T> void RemoveComponent();

		GameObject* GetParent() const;

		size_t GetAmountOfChildren() const;
		GameObject* GetChildAt(int index);
		void RemoveChild(int index);
		void AddChild(GameObject* gameObject);
		bool HasBeenInitialized() const;

	private:
		std::string m_Tag;
		void SetParent(GameObject* parent);
		GameObject* m_pParent;
		std::vector<BaseComponent*> m_Components;
		std::vector<GameObject*> m_Children;
		bool m_HasBeenInitialized;
	};

// ...

Component System

The engine supports a component system where components inherit from the BaseComponent class. These components are added to a gameobject to provide logic for rendering, player input or adding animation etc..

Examples

Creating a scene with physics enabled

auto& scene = SceneManager::GetInstance().CreateScene("Demo");
auto font = ResourceManager::GetInstance().LoadFont("Lingua.otf", 36);
AudioSystemLocator::GetAudio().LoadAudioClip(0, "Navi - Hey.mp3", true);

auto physics = std::make_shared<PhysicsManager>();
scene.Add(physics);

Creating a player game object

auto mrPepper = std::make_shared<GameObject>();
mrPepper->SetTag("Peter");

Adding components

auto pepperComp = mrPepper->AddComponent<MrPepperComponent>();
	
auto pepperTransform = mrPepper->AddComponent<TransformComponent>();
pepperTransform->SetSize(50.0f, 50.0f);
pepperTransform->Translate(150.0f, 100.0f);
	
mrPepper->AddComponent<RenderComponent>()->SetTexture("spritesheet.png");
mrPepper->AddComponent<AnimationComponent>();
mrPepper->AddComponent<RigidBodyComponent>();
auto collider = mrPepper->AddComponent<CircleCollider>();
collider->SetRadius(25.0f);

Mapping Controller Buttons

InputManager::GetInstance().AddButtonMapping(ControllerButton::DPad_Right, std::make_shared<MoveRightCommand>(pepperComp), ButtonBehaviour::Pressed, 0);
InputManager::GetInstance().AddButtonMapping(ControllerButton::DPad_Left, std::make_shared<MoveLeftCommand>(pepperComp), ButtonBehaviour::Pressed, 0);
InputManager::GetInstance().AddButtonMapping(ControllerButton::DPad_Up, std::make_shared<MoveUpCommand>(pepperComp), ButtonBehaviour::Pressed, 0);
InputManager::GetInstance().AddButtonMapping(ControllerButton::DPad_Down, std::make_shared<MoveDownCommand>(pepperComp), ButtonBehaviour::Pressed, 0);
InputManager::GetInstance().AddButtonMapping(ControllerButton::ButtonA, std::make_shared<PlaySoundCommand>(), ButtonBehaviour::DownThisFrame);

Mapping Keyboard Buttons

InputManager::GetInstance().AddKeyboardMapping(KeyboardButton::RightArrow, std::make_shared<MoveRightCommand>(pepperComp), ButtonBehaviour::Pressed);
InputManager::GetInstance().AddKeyboardMapping(KeyboardButton::LeftArrow, std::make_shared<MoveLeftCommand>(pepperComp), ButtonBehaviour::Pressed);
InputManager::GetInstance().AddKeyboardMapping(KeyboardButton::UpArrow, std::make_shared<MoveUpCommand>(pepperComp), ButtonBehaviour::Pressed);
InputManager::GetInstance().AddKeyboardMapping(KeyboardButton::DownArrow, std::make_shared<MoveDownCommand>(pepperComp), ButtonBehaviour::Pressed);

Adding the created object to the scene

scene.Add(mrPepper);

Building using CMAKE

Bumblebee supports CMAKE builds for both x86 and x64.

WIP Features

• Scripting via LUA
• Visual Game Editor
• Unit Tests