What is Nu and What it Can Do - bryanedds/Nu GitHub Wiki

A Mature, Functional, 2D and 3D Game Engine written in F#

Let's expand on each of those terms –

Mature

Nu is mature and exposes multiple levels of programmability depending on your performance needs. For high-level programming, there’s the MVU-like declarative MMCC programming API. Alternatively, there's the ImGui-inspired declarative ImNui API. Below that, there's the classic Nu API where everything is done with manual world and entity transformations, with fine-grained render calls exposed directly.

There is a 2D tile map system that utilizes Tiled#, a 3D terrain system, 2D physics via Aether Physics, and 3D physics via Bullet. 2D and Physically-Based 3D rendering are done with cross-platform OpenGL 4.1. Audio and other IO systems are handled in a cross-platform way with SDL2. There is also an asset management system via AssetGraph to make sure your game can run on memory-constrained devices such as mobile. There is a declarative special effects system called, appropriately enough, EffectSystem, as well as an efficient ParticleSystem, and a threaded 3D model animation system. On top of everything, there is a built-in WYSIWYG editor with live content and hot code reloading called Gaia which can undo and redo gameplay for advanced development and debugging scenarios.

Functional (w/ Imperative Configuration)

By default in the editor, Nu is configured to run in an immutable mode. In this mode, all of the simulation backing data encapsulated behind the World API is implemented with functional data structures that can be snapshotted and arbitrarily restored. This snapshotting is how Nu's editor, Gaia, implements its Undo and Redo operations. However, for optimal performance, Nu is configured to use mutating data structures under the hood instead when outside of the editor. Nu can be configured to run either way in both contexts, however.

2D and 3D Game Engine

Nu is not a code library. It is a game software framework. Thus, it sets up specific ways of approaching the design of 2D and 3D games. But because Nu is intended to be a broadly generic toolkit for 2D and 3D game development, it is made available via an engine source forking model rather than as a black-box nuget library.

F#

We know what F# is, so why use it? First, because of its cross-platform nature. Nu runs on .NET as well as Mono for portability to Linux and other platforms. Beyond that, F# is probably the best mainstream language available for writing a cross-platform functional game engine. Unlike Clojure, F#’s static type system makes the code easier to reason about and potentially more efficient. Unlike Scala, F# offers a simple and easy-to-use semantic model. Unlike Haskell, you get an intuitive and a well-tooled debugging experience, with no need babysit effects / monads / etc. Unlike JVM languages generally, F# allows us to code and debug with Visual Studio. Finally, game developers likely have more familiarity with the .NET ecosystem than the JVM, so that leverage is at hand.

Model-View-Update via MMCC

I have said many times that Model-View-Update (or MVU) is the 'killer app' of functional programming. Until MVU came along, most arguments about the benefits of functional programming resided primarily in the space of the theoretical. But when Elm introduced the world to MVU with its incredibly clean authoring form factor, the space of discussion changed forever.

With Nu's generalization of MVU via MMCC (Model-Message-Command-Content), it is the first and still only practical game engine positioned to bring the killer benefits of this declarative development form factor to game developers.

Immediate Mode Programming via ImNui

While MMCC might be better in a larger engineering team environment given its total game logic and simulation separation, smaller teams and individuals may prefer the new alternate high-level API called ImNui. It provides for a more inline, procedural style of game development similar to ImGui but without its restrictions.

Nu's Value Systems

In this talk Platform as a Reflection of Values, some sample values were placed on the slides with some of them highlighted according to how a given platform prioritizes them. I thought it might be useful to do something similar for Nu -

DEV NOTE: Nu on Windows currently uses SDL2-2.28.5-win32-x64, SDL2_image-2.8.2-win32-x64, SDL2_ttf-2.22.0-win32-x64, and SDL2_mixer-2.8.0-win32-x64.