Little Engine

A simple 3D game engine using C++20 and Vulkan.

Demo video (running le-example)

little-engine.example.mp4

Features

Requirements

Runtime

OS with desktop environment and Vulkan loader (libvulkan1.so / vulkan1.dll)
- Windows 10
- Linux: X, Wayland (untested)
- Mac OSX: untested, will require MoltenVk
GPU supporting Vulkan 1.3+, its driver, and loader

Development

CMake 3.23+
C++20 compiler and stdlib
OS with desktop environment and Vulkan loader (libvulkan1.so / vulkan1.dll)
- Windows 10
- Linux: X, Wayland (untested)
- Mac OSX: untested, will require MoltenVk
GPU supporting Vulkan 1.3+, its driver, and loader
glslc for compiling glsl shaders to SPIR-V
(Optional) Vulkan SDK for validation layers (contains glslc)

Usage

LittleEngine (le::little-engine) is a library intended to be built from source and linked statically, it currently does not support any installation / packaging. Link to it via CMake: target_link_libraries(foo PRIVATE le::little-engine).

LittleEngine Scene (le::le-scene) is an optional wrapper that provides Entity, Component, Scene, Runtime, and other convenience facilities.

Default shaders are provided as GLSL sources in shaders/. (These can be compiled to SPIR-V into your data directory using LittleEngine's tools.)

See example for a basic example that renders an animated skinned mesh and some text, and responds to input. The demo video above showcases this very example.

Building

Clone this repository somewhere.
Use CMake and a generator of your choice to configure an out-of-source build (build and out are ignored in git).
If using CMake 3.20+ / Visual Studio in CMake mode / CMake Tools with VSCode, CMakePresets.json can be utilized (and/or extended via CMakeUserPresets.json) for convenience.
- Use cmake --preset <name> to configure and cmake --build --preset <name> to build on the command line.
- Visual Studio CMake and VS Code CMake Tools should pick up the presets by themselves.
For other scenarios, use CMake GUI or the command line to configure and generate a build.
- Command line: cmake -S . -B out && cmake --build out.
- If using an IDE generator, use CMake GUI to configure and generate a build, then open the project/solution in the IDE and build/debug as usual.

Tools

LittleEngine provides some basic tools separate from the engine for building data. There are two main aspects to building data:

Shaders

The engine expects shaders to be in SPIR-V binary format. Custom shaders can be used as long as the shader layouts are compatible, and custom descriptor sets are updated every frame, if any. The engine uses a single global pipeline layout and buffered descriptor sets per camera and per render object.

Meshes

The engine uses custom formats for materials, animations, skeletons, and meshes. GLTF support is built-in, and meshes from such assets can be imported using le::importer. Contributions for importing other formats are welcome.

Note: if your game / app only uses programmatically generated geometry, this step is not required as you won't be loading any mesh data. Images can be loaded as textures directly, the JSON that's generated by the importer is optional.

glsl2spirv

This tool uses glslc by default to compile GLSL shaders to SPIR-V. It takes the source and desitnation directories as optional arguments, and reproduces the source file tree at the destination, with each compiled shader being suffixed with .spv. This suffix is optional in Uris in-game, the shader assets will automatically add them if not present.

If shaders are frequently modified, it is recommended to have a custom target in CMake that invokes glsl2spirv, to ensure a build run always uses up-to-date shaders.

le-importer

This tool imports GLTF meshes into LittleEngine meshes, geometries, materials, textures, animations, and skeletons.

External Dependencies

Misc

Original repository

LICENCE

karnkaul/LittleEngineVk

karnkaul

Reviews

Repository Details