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Engine Modules

Olympe Engine is organized into several major modules, each with specific responsibilities. This modular architecture makes the engine maintainable, testable, and extensible.

Core Engine​

GameEngine​

File: Source/GameEngine.h, Source/GameEngine.cpp

The GameEngine class is the top-level singleton that orchestrates the entire engine. It:

  • Manages the main game loop
  • Owns and coordinates major subsystems (InputsManager, VideoGame, DataManager)
  • Provides access to the main SDL renderer
  • Tracks frame delta time for smooth updates
GameEngine& engine = GameEngine::GetInstance();
engine.Initialize();
engine.Process(); // Called every frame

World​

File: Source/World.h, Source/World.cpp

The World class implements the ECS architecture and manages the game world state:

  • Entity Management: Creates, destroys, and tracks all entities
  • Component Storage: Manages component pools for all component types
  • System Registry: Registers and updates all ECS systems
  • Level Loading: Loads levels from Tiled TMX files via TiledLevelLoader
  • Prefab System: Instantiates entities from JSON blueprints
  • Tileset Management: Handles tile-based rendering

Key responsibilities:

  • Entity lifecycle management
  • Component registration and access
  • System execution ordering
  • Level state management
World& world = World::GetInstance();
EntityID entity = world.CreateEntity();
world.AddComponent<Position_data>(entity, position);

VideoGame​

File: Source/VideoGame.h, Source/VideoGame.cpp

Manages high-level game state and player management:

  • Player addition/removal
  • Game state transitions (play, pause, quit)
  • Event handling coordination
  • Game-specific logic coordination

ECS Systems​

All systems inherit from ECS_System and process entities with specific component signatures.

Rendering System​

Files: Source/ECS_Systems.cpp, Source/Rendering/IsometricRenderer.cpp

Handles all entity rendering:

  • Sprite rendering with transform
  • Multi-layer rendering with z-ordering
  • Camera-relative rendering
  • Isometric projection support
  • Tile layer rendering

Key functions:

  • RenderEntitiesForCamera(): Renders all visible entities for a camera
  • RenderMultiLayerForCamera(): Handles layered rendering with depth sorting

AI System​

Files: Source/ECS_Systems_AI.cpp, Source/ECS_Systems_AI.h

Processes AI entities using behavior trees:

  • Evaluates behavior tree nodes
  • Updates AI blackboard data
  • Handles AI state transitions
  • Processes patrol routes and waypoints

Requires components:

  • AIBlackboard_data
  • AIBehaviorTree_data
  • Position_data

Physics System​

Handles physics simulation and collision:

  • Velocity integration
  • Collision detection using bounding boxes
  • Collision response
  • Trigger volume detection

Requires components:

  • Position_data
  • Velocity_data
  • BoundingBox_data

Camera System​

Files: Source/ECS_Systems_Camera.cpp, Source/ECS_Systems_Camera.h

Manages camera behavior and viewport:

  • Camera following (follow player entities)
  • Camera bounds and constraints
  • Viewport transformation
  • Multi-camera support for split-screen

Requires components:

  • CameraFollow_data
  • CameraTransform_data

Input System​

Files: Source/ECS_Systems.cpp, Source/InputsManager.cpp

Processes player input and updates entity state:

  • InputEventConsumeSystem: Consumes input events and updates ECS components
  • InputSystem: Processes entities with Controller_data components
  • GameEventConsumeSystem: Handles gameplay events (pause, quit, etc.)

Integrates with:

  • Keyboard, mouse, and gamepad input
  • Player binding system
  • Input profiles and action mapping

Prefab Factory​

File: Source/PrefabFactory.cpp, Source/prefabfactory.h

Creates entities from JSON blueprint definitions:

  • Parses JSON blueprint files
  • Instantiates entities with specified components
  • Handles component overrides for level instances
  • Validates blueprint schemas

Used for data-driven entity creation without hardcoding in C++.

EntityID guard = PrefabFactory::CreateEntityFromBlueprint(
    "Blueprints/EntityPrefab/guard.json"
);

PrefabScanner​

File: Source/PrefabScanner.cpp, Source/PrefabScanner.h

Scans directories for blueprint files and maintains a registry:

  • Discovers available blueprints
  • Validates blueprint files
  • Provides blueprint metadata to editors
  • Supports hot-reloading of blueprints

Blueprint Editor​

Files: Source/BlueprintEditor/*.cpp, OlympeBlueprintEditor/

Visual editor for creating and modifying entity blueprints:

  • ImGui-based interface
  • Component editing
  • Blueprint validation
  • Real-time preview
  • Dependency scanning (for behavior trees)

Standalone application: OlympeBlueprintEditor.exe

Tiled Level Loader​

Files: Source/TiledLevelLoader/*

Loads and parses Tiled TMX map files:

  • Parses Tiled TMX XML format
  • Loads tilesets and tile layers
  • Extracts entity instances from object layers
  • Handles layer properties (z-order, visibility)
  • Converts Tiled coordinates to engine coordinates

Integration:

  • Called by World::LoadLevel()
  • Creates tile chunks for rendering
  • Instantiates entity prefabs from Tiled objects

Input System​

Files: Source/InputsManager.cpp, Source/InputDevice.cpp, Source/InputConfigLoader.cpp

Multi-device input management:

Device Management​

  • Keyboard input via KeyboardManager
  • Gamepad input via JoystickManager
  • Mouse input via MouseManager
  • Hot-plug support (add/remove controllers at runtime)

Input Mapping​

  • JSON-based input profiles (Config/olympe-config.json)
  • Action mapping (jump, attack, move, etc.)
  • Player binding to devices
  • Context-aware input (gameplay vs UI)

Integration​

  • Publishes input events to EventQueue
  • Systems consume events via InputEventConsumeSystem
  • Updates Controller_data components on entities

Files: Source/AI/*.cpp, Source/system/NavigationGrid.h

Provides pathfinding and navigation:

  • Grid-based pathfinding (A* algorithm)
  • Navigation mesh support
  • Dynamic obstacle avoidance
  • Waypoint and patrol route systems

Used by:

  • AI behavior trees for movement
  • Player character for click-to-move
  • Projectiles for homing behavior

Pathfinding Integration​

  • PathfindingSystem: Processes pathfinding requests
  • MoveIntent_data: Component for movement intentions
  • NavigationGrid: Grid representation for pathfinding

Behavior Trees​

Files: Source/AI/BehaviorTree.cpp, Source/AI/BehaviorTree.h

Data-driven AI decision-making:

  • Node types: Selector, Sequence, Condition, Action
  • JSON-based tree definitions
  • Built-in conditions: target detection, range checks, health
  • Built-in actions: move, attack, patrol, wander
  • Blackboard for AI memory

Common behaviors:

  • Wander: Random exploration
  • Patrol: Follow waypoint routes
  • Chase: Pursue target
  • Flee: Escape from threat

See Behavior Trees Overview for details.

Data Manager​

File: Source/DataManager.cpp, Source/DataManager.h

Centralized data and resource management:

  • Texture loading and caching
  • Asset lifetime management
  • Resource path resolution
  • Shared resource access
DataManager& dm = DataManager::GetInstance();
SDL_Texture* texture = dm.LoadTexture("Resources/sprite.png");

Module Dependencies​

GameEngine
  ├── InputsManager
  │     ├── KeyboardManager
  │     ├── JoystickManager
  │     └── MouseManager
  ├── VideoGame
  │     └── World
  │           ├── ECS Systems
  │           │     ├── InputSystem
  │           │     ├── AISystem
  │           │     ├── PhysicsSystem
  │           │     ├── CameraSystem
  │           │     └── RenderingSystem
  │           ├── PrefabFactory
  │           │     └── PrefabScanner
  │           ├── TiledLevelLoader
  │           └── TilesetManager
  ├── DataManager
  └── OptionsManager

Build Configuration​

From CMakeLists.txt:

  • C++ Standard: C++14
  • Main Targets:
    • OlympeEngine: Runtime game executable
    • OlympeBlueprintEditor: Standalone blueprint editor
    • OlympeCore: Shared library for editor functionality
    • TiledLevelLoader: Static library for Tiled integration

Build options:

option(BUILD_RUNTIME_ENGINE "Build runtime engine executable" ON)
option(BUILD_BLUEPRINT_EDITOR_STANDALONE "Build Blueprint Editor Standalone executable" ON)

Next Steps​