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Stevnbak / StevEngine

Game engine made in C++
MIT License
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StevEngine

StevEngine is a customizable game engine C++ library.

Features includes:

Table of Contents

Modules

The engine constists of multiple modules which can be enabled or disabled during the cmake build process.

These modules are:

Base

The base of the engine consists of the main engine setup, resource manager, logging, scenes, game-objects and component system.

The main engine setup handles the game window, and main engine loop.

The resource manager handles how files can be used for engine related aspects such as loading objects or scenes from files, audio, images etc.

The logging system handles logging both game and engine information to a file and in debug mode also to the console.

A scene handles all its game-objects which in turn handles its components, more than one scene can exist but only one can be active at a time.

Game-objects are the main way to interact with the engine, a game-object can have other game-objects as children as well as components. Components are how custom behaviour (both game specific stuff and general stuff like rendering and physics) can be added to a game-object.

This is the only module which cannot be disabled.

Inputs

The input manager handles inputs from the mouse and keyboard through SDL input events.

Can be disabled by setting the cmake build option "USE_INPUTS" to OFF".

Data & Settings

The data and settings managers handles saving player data and settings to a local folder on the user's machine, which will persist across game restarts.

The settings manager handles saving player settings to a local file on the user's machine, which will persist across game restarts. This is also the system that is used for for logging to a file. It is therefore not recommended to disable this.

Can be disabled by setting the cmake build option "USE_PLAYER_DATA" to OFF".

OpenGL Renderer

The OpenGL renderer is the only renderer in the engine, it handles (once it's complete) rendering primitives, models, textures, lighting etc.

Can be disabled by setting the cmake build option "USE_RENDERER_GL" to OFF.

Physics

Physics is implemented as components, but is using Jolt Physics as the backbone.

Can be disabled by setting the cmake build option "USE_PHYSICS" to OFF".

Audio

The audio system allows playing audio through the use of SDL_Mixer.

Can be disabled by setting the cmake build option "USE_AUDIO" to OFF".

Setup & Building

This project is tested and built to be working on Linux (Ubuntu) and Windows (Using Visual Studio).

And uses CMake as the build system

Setup project & dependencies

Clone this repository by running:

git clone https://github.com/Stevnbak/StevEngine.git

Clone and initialize submodules by running:

git submodule update --init

Install SDL2, SDL2_Image and SDL2_Mixer system wide:

[!IMPORTANT] When downloading for windows make sure to download the -devel-X.X.X-VC option.

Building or installing glad:

[!WARNING] Building glad requires a python intepreter installed and added to the path.

Alternatively glad can be generated online through this link: https://gen.glad.sh/#generator=c&api=gl%3D4.4&profile=gl%3Dcore%2Cgles1%3Dcommon and the build optiosn BUILD_GLAD can be set to OFF and GLAD_DIR should be set to the directory of the installed GLAD files.

(This can be done by adding -DBUILD_GLAD=OFF -DGLAD_DIR=<glad_path> to the cmake command)

Linux

Build StevEngine and all other external libraries by running CMake with the following command:

cd build && CXX=<compiler> cmake .. --build -DCMAKE_BUILD_TYPE=<type>

[!IMPORTANT]

  • Replace <compiler> with your c++ compiler such as g++ or clang++.
  • Replace <type> with Release or Debug.

[!NOTE] The different build options can be set by adding -DOPTION=VALUE to the end of the command.

[!NOTE] This can take a few minutes on the first build, as it will be building dependencies.

Windows

Create a Visual Studio solution with all dependencies and build process setup by running CMake with the following command:

cmake -S . -B VS2022 -G "Visual Studio 17 2022" -A x64 -DCMAKE_PREFIX_PATH="<cmake_module_path>" -DCMAKE_BUILD_TYPE=<type>

[!IMPORTANT]

  • Replace <cmake_module_path> with the path to the previously downloaded SDL libraries.
  • Replace <type> with Release or Debug.
  • Replace Visual Studio 17 2022 with your Visual Studio version.

[!NOTE] The different build options can be set by adding -DOPTION=VALUE to the end of the command.

This solution can now be found in the folder VS2022 and building the project can be done from Visual Studio.

Build options

The engine has build options for using the engine with the features and in the way you want to use it.

These options are:

Usage

To start using StevEngine for your own project, follow these 3 steps:

1. Including the library

Using the StevEngine library requires including the built static library in your own C++ project, and that the StevEngine header files are included.

This can be done simply through adding StevEngine as a CMake submodule:

add_subdirectory(path/to/StevEngine)
target_link_libraries(target PUBLIC/PRIVATE/INTERFACE StevEngine)

Or include the StevEngine library through any other means of adding a static library to your build system.

2. Creating engine instance

To start running StevEngine and all it's subsystems, the first step is to create the instance of the StevEngine::Engine class.

This can be any form of allocated memory, as long as it stays alive for the entire program.

The StevEngine::Engine object and all enabled subsystems is created through the function StevEngine::CreateEngine, that takes a couple of project specific arguments (such as title, target FPS and window options).

Example of creating the engine object inside the main function:

int main(int argc, char** argv) {
    StevEngine::CreateEngine("Game title", {});
    //Rest of the main function...
}

3. Starting the engine loop

After creating the engine, and any GameObjects used by the project. The main loop of the engine can be started by simply calling the Start method of the engine object:

int main(int argc, char** argv) {
    StevEngine::CreateEngine("Game title", {});
    //Rest of the main function...
    return StevEngine::engine->Start();
}

[!NOTE] The engine object can always be accessed through StevEngine::engine

[!IMPORTANT] This function will run the entire engine, and will only return a status code once the game is closed by the user or the program. It should therefore be called at the very end of the main function.