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U3D

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U3D is a open source, lightweight, cross-platform 2D and 3D game engine implemented in C++ and released under the MIT license. Forked from Urho3D and greatly inspired by OGRE and Horde3D.

Main website: https://u3d.io/

License

Licensed under the MIT license, see LICENSE for details.

Features

U3D Screenshot

Cross-platform support: Windows, Linux, macOS, iOS, tvOS, Android, Raspberry Pi (and other generic ARM boards), and Web with Emscripten
Powerful and configurable rendering pipeline, with implementations for forward, light pre-pass and deferred rendering
OpenGL, OpenGL ES, WebGL and Direct3D11
All-in-one editor built with ActionScript, allowing you to easily customize the editor to your game needs
Two scripting languages available for creating game logic: Lua and AngelScript
UI, localization and database subsystems
Component based scene model
Skeletal, vertex morph and node animation
Point, spot and directional lights
Cascaded shadow maps
Particle rendering
Geomipmapped terrain
Static and skinned decals
LODs
Automatic instancing
Software rasterized occlusion culling
Post-processing
HDR and PBR rendering
2D sprites and particles that integrate into the 3D scene
Task-based multithreading
Hierarchical performance profiler
Scene, object and prefab load/save in binary, XML and JSON formats
Keyframe animation of object attributes
Background loading of resources
Keyboard, mouse, joystick and touch input
High-performance math library
Physics powered by Bullet and Box2D
Networking powered by SLikeNet
Pathfinding and Crowd Simulation via Recast/Detour
Supported images: JPEG, PNG, TGA, BMP, PSD, GIF, HDR
Compressed image support: DDS, KTX, PVR
Import virtually any 3D file format via Assimp
2D and 3D audio playblack, Ogg Vorbis and WAV support
TrueType font rendering
Built as a single external library, can be linked statically or dynamically

Design Goals

Productive: Do not reinvent the wheel. Engine should reduce development time. Less yak shaving, more game making.
Fast: Compile and run fast. Parallelize when possible.
Modular: Only use what you need. Flexibility for power users.

Conventions

U3D uses the following conventions and principles:

Left-handed coordinates. Positive X, Y & Z axes point to the right, up, and forward, and positive rotation is clockwise.
Degrees are used for angles.
Clockwise vertices define a front face.
Audio volume is specified from 0.0 (silence) to 1.0 (full volume)
Path names use slash instead of backslash. Paths will be converted internally into the necessary format when calling into the operating system.
In the script API, properties are used whenever appropriate instead of Set...() and Get...() functions. If the setter and getter require index parameters, the property will use array-style indexing, and its name will be in plural. For example model->SetMaterial(0, myMaterial) in C++ would become model.materials[0] = myMaterial in script.
Raw pointers are used whenever possible in the classes' public API. This simplifies exposing functions & classes to script, and is relatively safe, because SharedPtr & WeakPtr use intrusive reference counting.
When an object's public API allows assigning a reference counted object to it through a Set...() function, this implies ownership through a SharedPtr. For example assigning a Material to a StaticModel, or a Viewport to Renderer. To end the assignment and free the reference counted object, call the Set...() function again with a null argument.
No C++ exceptions. Error return values (false / null pointer / dummy reference) are used instead. Script exceptions are used when there is no other sensible way, such as with out of bounds array access.
Feeding illegal data to public API functions, such as out of bounds indices or null pointers, should not cause crashes or corruption. Instead errors are logged as appropriate.
Third party libraries are included as source code for the build process. They are however hidden from the public API as completely as possible.

Community

U3D's development is community-driven and completely independent, empowering developers to build and design better tools to help indie game development. We invite you to familiarize yourself with our Code of Conduct and get to know us on:

Discord: Community chat room
GitHub Discussions: Technical discussions about the roadmap, issues, bugs

If you'd like to help build U3D, we have a guide just for you! Check it out: Contributor Guide.

Credits

U3D is greatly inspired by Urho3D, OGRE and Horde3D. Additional inspiration & research used:

Rectangle packing by Jukka Jylänki (clb) http://clb.demon.fi/projects/rectangle-bin-packing
Tangent generation from Terathon http://www.terathon.com/code/tangent.html
Fast, Minimum Storage Ray/Triangle Intersection by Möller & Trumbore http://www.graphics.cornell.edu/pubs/1997/MT97.pdf
Linear-Speed Vertex Cache Optimisation by Tom Forsyth http://home.comcast.net/~tom_forsyth/papers/fast_vert_cache_opt.html
Software rasterization of triangles based on Chris Hecker's Perspective Texture Mapping series in the Game Developer magazine http://chrishecker.com/Miscellaneous_Technical_Articles
Networked Physics by Glenn Fiedler http://gafferongames.com/game-physics/networked-physics/
Euler Angle Formulas by David Eberly https://www.geometrictools.com/Documentation/EulerAngles.pdf
Red Black Trees by Julienne Walker http://eternallyconfuzzled.com/tuts/datastructures/jsw_tut_rbtree.aspx
Comparison of several sorting algorithms by Juha Nieminen http://warp.povusers.org/SortComparison/

U3D uses the following third-party libraries:

AngelScript 2.35.1 WIP (http://www.angelcode.com/angelscript)
Boost 1.64.0 (http://www.boost.org) - only used for AngelScript generic bindings
Box2D 2.3.2 WIP (http://box2d.org)
Bullet 3.06+ (http://www.bulletphysics.org)
Civetweb 1.7 (https://github.com/civetweb/civetweb)
FreeType 2.8 (https://www.freetype.org)
{fmt} 9.1.0 (https://fmt.dev/)
GLEW 1.13.0 (http://glew.sourceforge.net)
SLikeNet (https://github.com/SLikeSoft/SLikeNet)
libcpuid 0.4.0+ (https://github.com/anrieff/libcpuid)
Lua 5.1 (https://www.lua.org)
LuaJIT 2.1.0+ (http://www.luajit.org)
LZ4 1.7.5 (https://github.com/lz4/lz4)
MojoShader (https://icculus.org/mojoshader)
Mustache 1.0 (https://mustache.github.io, https://github.com/kainjow/Mustache)
nanodbc 2.12.4+ (https://lexicalunit.github.io/nanodbc)
Open Asset Import Library 5.4.3 (http://assimp.sourceforge.net)
pugixml 1.13 (http://pugixml.org)
rapidjson 1.1.0 commit 2024/12/10 (https://github.com/Tencent/rapidjson/commit/58c6938b73c8685d82905ed55ec5b59e8f163687)
Recast/Detour (https://github.com/recastnavigation/recastnavigation)
SDL 2.30.9 (https://www.libsdl.org)
SQLite 3.36.0 (https://www.sqlite.org)
StanHull (https://codesuppository.blogspot.com/2006/03/john-ratcliffs-code-suppository-blog.html)
stb_image 2.29 (https://nothings.org)
stb_image_write 1.16 (https://nothings.org)
stb_rect_pack 1.01 (https://nothings.org)
stb_vorbis 1.22 (https://nothings.org)
tolua++ 1.0.93 (defunct - http://www.codenix.com/~tolua)
WebP (https://chromium.googlesource.com/webm/libwebp)
ETCPACK (https://github.com/Ericsson/ETCPACK)
Tracy 0.7.6 (https://github.com/wolfpld/tracy)
DXT / PVRTC decompression code based on the Squish library and the Oolong Engine.

Media credits

Jack and mushroom models from the realXtend project. (https://www.realxtend.org)
Ninja model and terrain, water, smoke, flare and status bar textures from OGRE.
BlueHighway font from Larabie Fonts.
Anonymous Pro font by Mark Simonson.
NinjaSnowWar sounds by Veli-Pekka Tätilä.
PBR textures from Substance Share. (https://share.allegorithmic.com)
IBL textures from HDRLab's sIBL Archive.
Dieselpunk Moto model by allexandr007.
Mutant & Kachujin models from Mixamo.
Skies from Polyhaven. (https://polyhaven.com/license)

License / copyright information included with the assets as necessary. All other assets (including shaders) by U3D authors and licensed similarly as the engine itself.

Contributors