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1. What is Overload

1.1. Description

Overload is an alternative game engine, inspired by industry standards, initiated by Benjamin VIRANIN, Max BRUN and Adrien GIVRY. Overload is now a community project, opened to any contribution.

Overload pillars are:

Simplicity
Documentation
High-quality modern C++ code

1.2. Modules

Overload is divided into 12 modules (10 DLLs and 2 executables):

1.2.1. Overload SDK

The Overload SDK is the core of the engine. It is a set of libraries that our applications (OvGame and OvEditor) are using. We designed theses libraries with reusability in mind. They are extremely modular and easy to extract from a game engine context.

OvAnalytics: Code and hardware profiling
OvDebug: Logging, assertions
OvTools: Serialization, ini files, events, time
OvMaths: Vectors, Matrices, Quaternion, Transform
OvAudio: Wraps irrKlang
OvPhysics: Wraps Bullet3
OvRendering: Rendering engine using OpenGL
OvWindowing: GLFW + Windows API wrapper
OvUI: Dear imGui wrapped into an event-based and component-based UI system
OvCore: Mediator, resource management, scripting, component-based scene system

1.2.2. Overload Applications

OvGame: Uses OvCore, asset dependent, generic executable for any game built with Overload
OvEditor: Uses OvCore, expose game development to the end-user (From creation to building)

2. History of Overload

2.1. Context

Initially, Overload was a graduation project. We were 3 (Benjamin VIRANIN, Max BRUN and Adrien GIVRY) working on it for 5 months. We had to create a game engine from scratch, using the fewest libraries possible.

2.2. Goals

Our goals for this project were:

Understanding how to architect a game engine
Designing an application thinking of end-users
Making a game engine as simple as possible
Producing high-quality modern code
Creating a game with our engine
Dealing with a long-term project
Developping documentation for developers and end-users

2.3. Pre-production

We spent about a month designing our initial architecture. We tried to provide a technical solution with UML diagrams, flowcharts, package diagrams and use-case diagrams. This was a long and tedious work, but it really helped us to start the production with a clear vision of the engine. We defined some coding convention to ensure that all of our work will stay homogeneous during the production. Defining these kinds of rules is crucial to keep a maintainable code during the whole project.

2.4. Production

The production made us realize that we had a naive idea of what a game engine is. During this phase our architecture has evolved. We found that our initial architecture was sometimes too complex, non-optimal. We went back to architecture design multiple times during the project.

3. Features

3.1. Implemented

Here is a non-exhaustive list of Overload main features:

Game Editor
Lua scripting
Physically-based rendering (PBR)
Custom shaders support
Windows game building
Profiling tools (Editor and build)
Material editor
3D sound system
Rigidbody physics

3.2. To implement

Again, a non-exhaustive list of Overload in-coming features:

Shadow mapping
Custom post-processing
Renderer Hardware Interface (Multiple graphics backend support)
More input device support (Gamepad)
Prefab system
Skeletal animation
User scripts profiling

4. Details

4.1. Software

Visual Studio 2022 (previous versions should also be supported)

4.2. Dependencies

OpenGL with GLEW (Graphics API)
GLFW (Windowing and inputs)
Assimp (3D model loader)
Bullet3 (Physics)
irrKlang (Audio)
Tinyxml2 (XML Serializer)
SOL2 (Lua binder)
imGui (GUI)

4.3. Requirements

Overload requires:

RAM: 100MB
OS: Windows 7
GPU: Graphics card supporting OpenGL 4.3
CPU: x64

4.4. Compiling sources

Overload is using Premake5 to generate project files. To generate these project files, execute GenerateProjects.bat located at the root of the repository. By default, GenerateProjects.bat will generate project files for Visual Studio 2022. If you want to use another version of Visual Studio (vs2019, vs2017...) or another IDE (c.f. https://github.com/premake/premake-core/), you can execute GenerateProjects.bat from the command line with an argument. (ex: .\GeneratedProjects.bat vs2019)

Overload only targets Windows x64.