Paddle - Easy 2D browser games in Rust

Paddle is a game engine to make simple games for the web without headache.

I started this project in 2019 because I was baffled how hard it was to get the simplest Rust game running in the browser. I struggled especially with things like interactive UI elements. This is very easy from JavaScript, so why is it so hard from Rust?

So I started to experiment how I can bring the DOM and my Rust code closer together. The initial experimentation happens in projects outside this crate. Only once I see that a certain approach works, I will port it to Paddle and try to fit it in with the existing features. Hopefully, this will lead to a set of practically useful features. The final goals it to make building browser games with Rust as easy as it is with JavaScript!

There is still a long way for Paddle. At the same time, the browser support in other Rust game engines is getting better with every release and the community is very active. I am more than happy to see that! But so far, I still feel like Paddle would fill a niche of a purely web-focused engine which does not really exist, yet. So I keep at it for the forseeable future.

The exact scope Paddle will entail is not set in stone, yet. However, I try to keep this document updated with current plans for this crate.

0.1.0 Beta now published but API highly unstable. This is only released to crates.io for Paddlers, which uses this in the live-demo.

Design Principles

In the landscape of game engine design choices, Paddle makes the following tradeoffs:

• Focus on the best experience in web browsers and ignore other platforms entirely.
• Simplicity trumps performance and cleverness.
• Make the API as simple as possible to use for newbies. With that I mean anyone new to game development, new to Rust, or even new to programming in general. This is often different from simple for experienced programmers.

Goals Statement

A bit more specifically, the principles translate into the following goals for the crate.

• Highest priority features in the engine are those that make the developers' life easier. For example, provide a solution for loading assets over the network, display and style texts, create clickable images, ...
• Harness native browser capabilities like HTML + CSS user interfaces, SVG rendering, and more to come in the future.
• Compatibility with as many browser versions and devices as possible (Only WebGL 1 + WASM required, touch and mouse support for all browsers, etc.)
• The library should become beginner-friendly enough that it can be recommended for people's first Rust project to learn the language and for game jams where not everybody in the team knows a lot of Rust.
• Avoid complex public function signatures, such as traits with too many generic parameters.
• Simple programming interfaces over maximum efficiency when there is a conflict.
• Write easy-to-follow documentation.
• 2D graphics only (3D could be added later if it does not pollute the 2D API.)

Technical Overview

Implemented in Paddle

• Cross-browser input
• Screen resizing
• Custom WebGL layer
• Support for basic geometries and image drawing (Originally taken from quicksilver and adapted)
• Support for text placement on the screen
• Activity (frame) management

External Dependencies

• wasm-bindgen / web-sys / wasm-pack for deployment on the web
• div-rs for integration of HTML components
• nuts for activity management and (seemingly stateless) point-to-point messages and broadcasts

Core Principles

Frames Everything lives in so-called frames. These are activities that also occupy a space on the screen, where they can draw and receive user input. Multiple frames can be used to create UIs or to switch between scenes easily.

Work in progress, documentation will be added as the project matures...