Horizon Engine

A modern C++20 game engine built for FPS games, featuring an Entity-Component-System architecture, PBR rendering pipeline, and action-based input system.

I’m learning OpenGL, so this is a work in progress. Planning to migrate (or from zero)to Vulkan in the future. I’m using this project to learn and experiment with new technologies. Strictly keeping up with learnopengl.com

Features

Core Systems

• Entity-Component-System (ECS) - Data-oriented architecture for high performance
• Physics Integration - Rigid body dynamics using Jolt Physics
• Audio System - 3D spatial audio using miniaudio
• Action-Based Input - Abstract input mapping for keyboard, mouse, and gamepad
• Fixed-Timestep Game Loop - Deterministic physics at 60 Hz
• Memory Arena Allocator - Efficient memory management with std::pmr

Rendering

• OpenGL 4.1 PBR Renderer - Cross-platform graphics (macOS, Windows, Linux)
• Material System - First-class PBR materials with texture handles
• GLTF Model Loading - Full 3D model support via tinygltf
• HDR Pipeline - Bloom, tone mapping, exposure control
• SSAO - Screen-space ambient occlusion
• Shadow Mapping - Directional light shadows
• HDRI Skybox - Equirectangular environment maps

Tools & Editor

• Scene Serialization - JSON-based scene save/load (F5/F6)
• In-Game Editor - Entity hierarchy, material inspector, scene settings
• Debug Overlay - FPS, frame time, entity count (F3)
• ImGui Interface - Full debug tooling

Asset Management

• Handle-Based Registry - Textures, Models, Materials, Sounds
• Automatic Caching - Prevents duplicate asset loads
• Hot Reload Ready - Asset reloading infrastructure

Quick Start

Prerequisites

• CMake 3.21+
• C++20 compiler (Clang 14+, GCC 11+, MSVC 2022+)
• Git

Build

# Clone
git clone https://github.com/jackthepunished/horizon-engine.git
cd horizon-engine

# Configure & Build
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --parallel

# Run
./build/bin/horizon_game

Controls

Key	Action
W/A/S/D	Move
Mouse	Look around
Shift	Sprint
Space	Jump/Up
Ctrl	Crouch/Down
Tab	Toggle cursor
F3	Debug overlay
F5	Save scene
F6	Load scene
Esc	Quit/Menu

Architecture

horizon-engine/
├── engine/               # Core engine library
│   ├── assets/           # Textures, Models, Materials, Cubemaps
│   ├── audio/            # Spatial audio system
│   ├── core/             # Logging, memory, game loop
│   ├── ecs/              # Entity-Component-System
│   ├── physics/          # Jolt Physics integration
│   ├── platform/         # Window, input abstraction
│   ├── renderer/         # OpenGL renderer, shaders, framebuffers
│   ├── scene/            # Components, serialization
│   └── ui/               # ImGui integration
├── game/                 # Sample FPS game
│   └── src/              # Main loop, editor UI
├── assets/               # Shaders, textures, models
├── tests/                # Unit tests (Catch2)
└── third_party/          # External dependencies

Dependencies

All dependencies are fetched automatically via CMake FetchContent:

Library	Version	Purpose
GLFW	3.4	Windowing & Input
GLM	1.0.1	Math Library
spdlog	1.14.1	Logging
Catch2	3.5.2	Testing
Jolt	5.0.0	Physics Engine
miniaudio	0.11.21	Audio Engine
Dear ImGui	1.90.4	UI Library
stb_image	master	Image Loading
tinyobjloader	2.0.0	OBJ Model Loading
tinygltf	2.8.x	GLTF Model Loading
nlohmann/json	3.11.x	JSON Parsing

Testing

cd build && ctest --output-on-failure

100% tests passed, 0 tests failed out of 7

Roadmap

• Milestone 0: Repository & Build System

• Milestone 1: Core Systems (ECS, Input, Game Loop)

• Milestone 2: OpenGL Rendering (Shaders, Meshes, Camera)

• Milestone 3: Assets & Hot Reload

• Milestone 4: Physics (Jolt Integration)

• Milestone 5: Audio, AI, UI (Dear ImGui)

• Milestone 6: PBR Rendering, Materials, GLTF Loading

• Milestone 7: Skeletal Animation & Advanced Lighting

• Bone hierarchy & animation clips

• GPU skinning

• IBL (irradiance, prefiltered environment maps)

• Cascaded Shadow Maps

• Milestone 8: Render Architecture & Optimization

• Render pass system (Geometry, Shadow, Lighting, Post)

• Frustum culling & instanced rendering

• GLTF material extraction

• Milestone 9: Networking & Multiplayer (optional)

License

MIT License - see LICENSE for details.