Flecs engine

A fast, portable, low footprint, opinionated (but hackable), flecs native game engine.

The project is still WIP and currently only works on MacOS.

Usage

Build & run the engine:

cmake -S . -B build/debug
cmake --build build/debug
./build/debug/flecs

Building with bake3

The project can also be built with bake3. bake fetches and builds the external dependencies (glfw, cglm, wgpu-native, stb, tinyexr, cgltf, flecs) automatically via its bundle feature. Build and run an executable (the flecs_app target produces the flecs binary):

bake run flecs_app --local-env
bake run traffic --local-env

Build an executable (and the flecs_engine library it depends on) without running:

bake build flecs_app --local-env
bake build traffic --local-env

WebAssembly with bake3

bake3 can also cross-compile to WebAssembly with --target em:

bake build flecs_app --target em --local-env
bake build traffic --target em --local-env

This produces flecs.html / flecs.wasm / flecs.js (and traffic.*) under .bake/local_env/build/<app>/wasm32-Emscripten-debug/. bake automatically locates and activates the Emscripten SDK; if emcc is not already on PATH it sources emsdk_env.sh from $EMSDK, $EMSDK_DIR, or ~/GitHub/emsdk. On this target bake builds the dependency bundles with emcmake, skips the native GLFW/WebGPU dependencies, and uses Emscripten's -sUSE_GLFW=3 -sUSE_WEBGPU=1 ports instead.

Why should I use this?

You should probably not use this, unless:

• you want to quickly prototype ideas
• you want to build an engine but not start from 0
• you're OK with the limitations of the engine

Features

Geometry

• Primitive shapes:
  • Quad
  • Box
  • Triangle
  • TrianglePrism
  • RightTriangle
  • RightTrianglePrism
• Primitive meshes (parameterized mesh cache):
  • Cone
  • Cylinder
  • Sphere
  • IcoSphere
  • HemiSphere
  • NGon
• Meshes
• Instanced rendering

Assets

• glTF loader
• PNG loader
• DDS loader
• HDR / EXR loader (for HDRI)

Materials

• Metallic
• Roughness
• Cubemap based reflections
• Emissive
• Transmissive (rough/smooth objects)
• PBR textures
• Per-instance materials
• Shared materials

Lighting

• Directional light
• Point lights
• Spot lights
• Clustered light rendering
• Cascading shadow maps
• Image based lighting

Atmosphere

• Dynamic atmosphere
• Dynamic atmosphere IBL
• Distance fog
• Height based fog
• Sun disk
• Moon disk (w/phases)
• Starfield
• Time of day system

Effects

• Bloom
• SSAO
• Screen space sun shafts
• Auto exposure
• Tony McMapFace tone mapping

Misc

• Input handling
• Camera controller
• Movement systems
• Tracy profiling
• Image-based rendering regression testing
• MSAA
• GPU frustum culling
• Hi-Z occlusion culling
• Render to image

Dependencies

• cglm
• cgltf
• glfw
• stb_image
• tinyexr
• tracy

Assets used

• Kronos sample assets
• Niagra bistro
• Kenney

Screenshots