luminance, the elegant, safe, type-safe, stateless and simple graphics crate
luminance is an effort to make graphics rendering simple and elegant. It was originally imagined, designed and implemented by @phaazon in Haskell (here) and eventually ported to Rust in 2016. The core concepts remained the same and the crate has been slowly evolving ever since. At first used only by @phaazon for his Rust demoscene productions ( example here and here, using spectra) and a bunch of curious peeps, it has more visibility among the graphics ecosystem of Rust.
Currently, such an ecosystem is spread into several crates, ideas and people. It is highly recommended to read the great article about the ecosystem by @Icefoxen, here.
However, luminance is a bit different from what it was initially imagined for. People are looking for an easy-to-use crate, with good abstractions and safe-guards against all the bad and dangerous graphics API caveats. luminance has always been about providing a safe, type-safe and elegant API (being Haskell-based makes it heavily use type systems, for instance) but it has now a more accurate place in the ecosystem. Where gfx-hal provides you with an experience focused on down-to-metal performance and an API very similar to Vulkan’s, luminance provides an API that is, for sure, a bit less low-level — and hence, yes, it’s likely you will not have the same performances as with gfx-hal (even though no benchmarks have been done so far), and the API is not Vulkan-based — but easier to start with, especially if you don’t already have a background experience with OpenGL or Vulkan.
The strengths of luminance are:
- Easy to learn: the concepts, based on OpenGL, are applied to graphics, not general-purpose programming on GPU. Using luminance will help you wrap your fingers around what graphics programming is about and it will help you to, perhaps, jump to lower abstractions like gfx-hal, if you ever need to.
- Performant: by using Rust and being designed around the concept of good performances, luminance should allow you to build nice and fast simulations, animations and video games. Remember that games you played years ago didn’t have Vulkan and were impressive nonetheless. It’s unlikely you will get 100% out of your GPU by using luminance since it’s built over technologies that are not using 100% of your GPU. Unless you need and know exactly why you need 100% of your GPU, you should be just fine™.
- Elegant: the design is heavily based on functional programming concepts such as typeclasses, associated types, singleton types, existentials, contravariant resources, procedural macros, strong typing, etc. Plus, every bit of possible stateful computations is hidden behind a system of smart state, removing the need to worry about side-effects. luminance still has mutation (unless its Haskell version) but the Rust type system and borrow checker allows for safe mutations.
- Modern: the whole luminance ecosystem tries its best to stay up-to-date with Rust evolutions and features. On the same level, the underneath technologies are kept up-to-date and might even change if a more modern and more adapted one emerges (Vulkan might eventually get adopted but this is just an idea for now).
- Enough opinionated: a big bet with luminance was to make it opinionated, but not too much. It needs to be opinionated to allow some design constructs to be possible and optimize performance and allow for extra safety. However, it must not be too much to prevent it to become a framework. luminance is a library, not a framework, meaning that it will adapt to how you think you should design your software, not the other way around. That is limited to the design of luminance but you shouldn’t feel too hands-tied.
The luminance ecosystem
It is currently composed of four different crates:
- luminance: the core crate, exposing a graphics API that aims to be easy to learn, safe, type-safe, stateless and fun!
- luminance-derive: a companion crate to luminance you’re very likely to enjoy; it will help you derive important traits for your application or library to work. You should definitely invest some time in the documentation of this crate; it’s easy and well explained.
- luminance-windowing: a small interface crate for windowing purposes. It’s unlikely you will need it, but it provides some basic and shared data structures you might use.
- luminance-glfw: an implementation of luminance-windowing for GLFW (via glfw).
- luminance-glutin: an implementation of luminance-windowing for glutin.
luminance has two main and official mechanisms to learn:
- The examples. They are like unit tests: each introduces and focuses on a very specific aspect or feature. You should read them if you are interested in given feature. They’re not well suited to learn from scratch and they are weaker than a structured tutorial but more concise.
- The wiki. It contains various chapters, including tutorials and onboarding newcomers. It will not provide you with the best description of a given feature as it focuses more on the overall comprehension and explaining than code directly.
You should try both ways and see which one fits the best for you!
Those projects use luminance:
- A demoscene production by @phaazon, released at Evoke 2016 in the PC Demo category.
Outline 2017 Invitro.
- A demoscene production by @phaazon, released at Revision 2017 in the PC Demo category.
- A rendering library by @austinjones, designed to generate high-resolution digital paintings to be printed on canvas.